ArticlePDF Available

Nineteen new species of Alycaeidae from Myanmar and Thailand (Gastropoda: Caenogastropoda: Cyclophoroidea)

May 2021
Zootaxa 4973(1):001–061

DOI:10.11646/zootaxa.4973.1.1

Authors:

Barna Páll-Gergely

Plant Protection Institute, Centre for Agricultural Research

András Hunyadi

Jozef Grego

Independent Researcher

Alexander Reischütz

basement in a semi-detached house

Show all 5 authorsHide

Nineteen new species of the alycaeid genera Chamalycaeus, Dicharax, and Metalycaeus are described from Thailand and Myanmar: Chamalycaeus buaboke Páll-Gergely & A. Reischütz, n. sp., C. erawan Páll-Gergely & Hunyadi, n. sp., C. hirpex Páll-Gergely & A. Reischütz, n. sp., C. irmatallus Páll-Gergely, n. sp., C. krabiensis Páll-Gergely & A. Reischütz, n. sp., C. serratus Páll-Gergely & Auffenberg, n. sp., C. spiratus Páll-Gergely, n. sp., Dicharax (?) admirandus Páll-Gergely & Auffenberg, n. sp., D. cyclostoma Páll-Gergely, n. sp., D. ebrius Páll-Gergely & Auffenberg, n. sp., D. (?) gnomus Páll-Gergely, n. sp., D. mirounga Páll-Gergely, n. sp., D. ovatus Páll-Gergely & Auffenberg, n. sp., D. subroseus Páll-Gergely, n. sp., D. verrucosus Páll-Gergely & Hunyadi, n. sp., Metalycaeus anas Páll-Gergely & A. Reischütz, n. sp., M. aries Páll-Gergely & Auffenberg, n. sp., M. bicarinatus Páll-Gergely & Hunyadi, n. sp., M. pygmachos Páll-Gergely & Hunyadi, n. sp. Alycaeus kengtungensis Godwin-Austen, 1914 is moved to the synonymy of Metalycaeus heudei (Bavay & Dautzenberg, 1900). We also report exact localities of Dicharax ataranensis (Godwin-Austen, 1914), Dicharax notus (Godwin-Austen, 1914), and Dicharax omissus (Godwin-Austen, 1914). The new records extend the known distribution of Chamalycaeus and Metalycaeus in Thailand.

Shells of Chamalycaeus Möllendorff, 1897 species. A: Chamalycaeus buaboke Páll-Gergely & A. Reischütz, n. sp., holotype (NHMw 113484); B: Chamalycaeus canaliculatus (Möllendorff, 1894), lectotype (SMF 109468).

…

Chamalycaeus erawan Páll-Gergely & Hunyadi, n. sp., holotype (HNHM 104869).

…

Chamalycaeus irmatallus Páll-Gergely, n. sp. A: holotype (UF 279508); B: paratype (UF 551216).

…

Shells of Chamalycaeus Möllendorff, 1897 species. A: Chamalycaeus irmatallus Páll-Gergely, n. sp., NHMUK 1906.4.4.71; B: Chamalycaeus (?) armillatus (Benson, 1856), holotype (UMZC 102995).

…

+18

Chamalycaeus krabiensis Páll-Gergely & A. Reischütz, n. sp. A: holotype (site Th22, NHMw 113487); B: paratype (site Th21, NHMw 113488); C: Krabi Province, 1.7 km SE of Ao Luek Tai, Simon Aiken leg., 19 Mar. 2020, coll. SA.

…

Figures - uploaded by Barna Páll-Gergely

Content may be subject to copyright.

Content uploaded by Barna Páll-Gergely

Content may be subject to copyright.

https://doi.org/10.11646/zootaxa.4973.1.1

http://zoobank.org/urn:lsid:zoobank.org:pub:42EB4BF2-A571-4894-9EEF-783649A27E4F

ZOOTAXA

ISSN 1175-5326 (print edition)

ISSN 1175-5334 (online edition)

Accepted by M. Harzhauser: 19 Apr. 2021; published: 18 May 2021

4973

ZOOTAXA

Magnolia Press

Auckland, New Zealand

Zootaxa 4973 (1): 001–061

https://www.mapress.com/j/zt/

Nineteen new species of Alycaeidae from Myanmar and Thailand (Gastropoda:

Caenogastropoda: Cyclophoroidea)

BARNA PÁLL-GERGELY1*, ANDRÁS HUNYADI2, JOZEF GREGO3, ALEXANDER

REISCHÜTZ4 & KURT AUFFENBERG5

1Plant Protection Institute, Centre for Agricultural Research, Herman Ottó Street 15, Budapest, 1022, Hungary

2Adria sétány 10G 2/5., Budapest H-1148, Hungary

�

hunand@freemail.hu; https://orcid.org/0000-0003-3488-2817

3Horná Mičiná, 97401 Banská Bystrica, Slovakia

�

jozef.grego@gmail.com; https://orcid.org/0000-0002-4977-0415

4Puechhaimgasse 52, 3580, Horn, Austria

�

alexander.reischuetz@gmx.at; https://orcid.org/0000-0002-8844-7004

5Florida Museum of Natural History, University of Florida, Gainesville, 32611, USA

�

kurtauffenberg@gmail.com; https://orcid.org/0000-0001-9660-6776

*corresponding author.

�

pallgergely2@gmail.com; https://orcid.org/0000-0002-6167-7221

PÁLL-GERGELY ET AL.

BARNA PÁLL-GERGELY, ANDRÁS HUNYADI, JOZEF GREGO, ALEXANDER REISCHÜTZ & KURT

AUFFENBERG

NINETEEN NEW SPECIES OF ALYCAEIDAE FROM MYANMAR AND THAILAND

(GASTROPODA: CAENOGASTROPODA: CYCLOPHOROIDEA)

(Zootaxa 4973)

61 pp.; 30 cm.

18 May 2021

ISBN 978-1-77688-260-1 (paperback)

ISBN 978-1-77688-261-8 (Online edition)

FIRST PUBLISHED IN 2021 BY

Magnolia Press

P.O. Box 41-383

Auckland 1041

New Zealand

e-mail: magnolia@mapress.com

https://www.mapress.com/j/zt

No part of this publication may be reproduced, stored, transmitted or disseminated, in any form, or by any

means, without prior written permission from the publisher, to whom all requests to reproduce copyright

material should be directed in writing.

This authorization does not extend to any other kind of copying, by any means, in any form, and for any

purpose other than private research use.

ISSN 1175-5326 (Print edition)

ISSN 1175-5334 (Online edition)

Table of Contents

Abstract ...................................................................................................3

Introduction ................................................................................................4

Materials and Methods .......................................................................................4

Abbreviations ..............................................................................................4

Taxonomy and Systematics ....................................................................................5

Superfamily Cyclophoroidea J.E. Gray, 1847 .....................................................................5

Family Alycaeidae W.T. Blanford, 1864 ........................................................................5

Genus Chamalycaeus Möllendorff, 1897 ......................................................................5

Chamalycaeus buaboke Páll-Gergely & A. Reischütz n. sp. ...................................................5

Chamalycaeus erawan Páll-Gergely & Hunyadi n. sp. ........................................................8

Chamalycaeus hirpex Páll-Gergely & A. Reischütz n. sp. ....................................................11

Chamalycaeus irmatallus Páll-Gergely n. sp. ..............................................................14

Chamalycaeus krabiensis Páll-Gergely & A. Reischütz n. sp. .................................................17

Chamalycaeus serratus Páll-Gergely & Auffenberg n. sp. ....................................................19

Chamalycaeus spiratus Páll-Gergely n. sp. ................................................................21

Genus Dicharax Kobelt & Möllendorff, 1900 .................................................................21

Dicharax (?) admirandus Páll-Gergely & Auffenberg n. sp. ..................................................21

Dicharax ataranensis (Godwin-Austen, 1914) .............................................................25

Dicharax cyclostoma Páll-Gergely n. sp. .................................................................26

Dicharax ebrius Páll-Gergely & Auffenberg n. sp. ..........................................................28

Dicharax (?) gnomus Páll-Gergely n. sp. .................................................................29

Dicharax mirounga Páll-Gergely n. sp. ..................................................................31

Dicharax notus (Godwin-Austen, 1914) ..................................................................32

Dicharax omissus (Godwin-Austen, 1914) ................................................................38

Dicharax ovatus Páll-Gergely & Auffenberg n. sp. ..........................................................41

Dicharax stuparum Páll-Gergely & Hunyadi, 2018 .........................................................41

Dicharax subroseus Páll-Gergely n. sp. ..................................................................41

Dicharax verrucosus Páll-Gergely & Hunyadi n. sp. ........................................................44

Genus Metalycaeus Pilsbry, 1900 ...........................................................................45

Metalycaeus anas Páll-Gergely & A. Reischütz n. sp. .......................................................45

Metalycaeus aries Páll-Gergely & Auffenberg, n. sp. ........................................................49

Metalycaeus bicarinatus Páll-Gergely & Hunyadi n. sp. .....................................................52

Metalycaeus heudei (Bavay & Dautzenberg, 1900) .........................................................53

Metalycaeus pygmachos Páll-Gergely & Hunyadi n. sp. .....................................................55

Concluding remarks ........................................................................................56

Biogeography .............................................................................................56

Predation .................................................................................................59

Acknowledgements .........................................................................................59

References ................................................................................................59

Abstract

Nineteen new species of the alycaeid genera Chamalycaeus, Dicharax, and Metalycaeus are described from Thailand and

Myanmar: Chamalycaeus buaboke Páll-Gergely & A. Reischütz, n. sp., C. erawan Páll-Gergely & Hunyadi, n. sp., C.

hirpex Páll-Gergely & A. Reischütz, n. sp., C. irmatallus Páll-Gergely, n. sp., C. krabiensis Páll-Gergely & A. Reischütz,

n. sp., C. serratus Páll-Gergely & Auffenberg, n. sp., C. spiratus Páll-Gergely, n. sp., Dicharax (?) admirandus Páll-

Gergely & Auffenberg, n. sp., D. cyclostoma Páll-Gergely, n. sp., D. ebrius Páll-Gergely & Auffenberg, n. sp., D. (?)

gnomus Páll-Gergely, n. sp., D. mirounga Páll-Gergely, n. sp., D. ovatus Páll-Gergely & Auffenberg, n. sp., D. subroseus

Páll-Gergely, n. sp., D. verrucosus Páll-Gergely & Hunyadi, n. sp., Metalycaeus anas Páll-Gergely & A. Reischütz, n. sp.,

M. aries Páll-Gergely & Auffenberg, n. sp., M. bicarinatus Páll-Gergely & Hunyadi, n. sp., M. pygmachos Páll-Gergely

& Hunyadi, n. sp.

Alycaeus kengtungensis Godwin-Austen, 1914 is moved to the synonymy of Metalycaeus heudei (Bavay &

Dautzenberg, 1900). We also report exact localities of Dicharax ataranensis (Godwin-Austen, 1914), Dicharax notus

(Godwin-Austen, 1914), and Dicharax omissus (Godwin-Austen, 1914). The new records extend the known distribution

of Chamalycaeus and Metalycaeus in Thailand.

Key words: taxonomy, systematics, museum collections, biodiversity, shell

PÁLL-GERGELY ET AL.

Introduction

The Alycaeidae are distributed from India to Japan with 367 valid species and subspecies currently classified in

seven genera (Páll-Gergely et al. 2020; Jirapatrasilp et al. 2021).

The alycaeid species of Myanmar (Burma) were described during the Colonial Era by English malacologists

(Benson 1856; Blanford 1862, 1863; Godwin-Austen 1882–1920). No new information has been published in the

last hundred years. Similarly, a few alycaeid species from Thailand were described in the second half of the 19th

century by Haines (1858) and Möllendorff (1894). Some additional species were described from type localities in

the Thai-Myanmar border region (Godwin-Austen 1882–1920). In the last few decades, a few more species have

been described from Thailand by Thai and European malacologists (Panha & Burch 1997; Panha & Patamakanthin

2001; Maassen 2006; Dumrongrojwattana & Maassen 2008; Páll-Gergely & Hunyadi 2018). In a recent genus-level

revision of the Alycaeidae (Páll-Gergely et al. 2020), three hotspots, inferred by the highest number of known gen-

era, were identified: Peninsular Malaysia and Sumatra, northern Vietnam and southern China, and the southeastern

Himalaya region.

In the present paper we describe nineteen new alycaeid species from Myanmar and Thailand and add informa-

tion on the distribution, shell, and operculum morphology of some previously described species.

Materials and Methods

In the case of new species described here, 10–30 photographs were taken of each shell using a Keyence LHX5000

digital microscope, and merged into a single image with Photoshop. Photographs of other shells (mostly types in

museum collections) were taken with various photographic equipment in our laboratories and museum collections.

Shells were directly observed without coating under a low vacuum SEM (Hitachi S-2600N) at the Hungarian Natu-

ral History Museum.

Locality data presented with the specimen examined are provided verbatim from the specimen labels in most

cases. Measurements were taken of largest and smallest specimen.

We distinguish three regions of the teleoconch following Páll-Gergely et al. (2017: fig. 1A, B): Region 1 (R1)—

ranges from the beginning of the teleoconch to the beginning of the differently ribbed region where the sutural tube

lies; Region 2 (R2)—extends from the differently ribbed area to the constriction; and Region 3 (R3)—ranges from

the constriction to the peristome.

Abbreviations

CUMZ: Chulalongkorn University Museum of Zoology (Bangkok, Thailand)

HA: Collection of András Hunyadi (Budapest, Hungary)

HNHM: Hungarian Natural History Museum (Budapest, Hungary)

JG: Collection of Jozef Grego (Banská Bystrica, Slovakia)

NHM: The Natural History Museum (London, UK)

NHMUK: when citing lots deposited in the NHM

NHMW: Natural History Museum Vienna (Vienna, Austria)

NZSI: National Zoological Collection of the Zoological Survey of India (when cited specimens deposited in the

ZSI)

RE: Collection of the Reischütz family (Horn, Austria)

SA: Collection of Simon Aiken (York, UK)

SMF: Senckenberg Forschungsinstitut und Naturmuseum (Frankfurt am Main, Germany)

UF: Florida Museum of Natural History, University of Florida (Gainesville, USA)

UMZC: University Museum of Zoology (Cambridge, UK)

ZSI: Zoological Survey of India (Kolkata, India)

D: shell diameter

H: shell height

Taxonomy and Systematics

Superfamily Cyclophoroidea J.E. Gray, 1847

Family Alycaeidae W.T. Blanford, 1864

Genus Chamalycaeus Möllendorff, 1897

Alycaeus (Chamalycaeus) Möllendorff, 1897: 93.

Chamalycaeus — Páll-Gergely et al. 2017: 5–7; Páll-Gergely et al. 2020: 34.

Type species. Alycaeus (Chamalycaeus) fruhstorferi Möllendorff, 1897, by monotypy.

Diagnosis. Genus characterized by the combination of a spirally striated teleoconch, protoconch without spiral

striae, and wide umbilicus (see Páll-Gergely et al. (2020) for extended diagnosis and taxonomic remarks).

Chamalycaeus buaboke Páll-Gergely & A. Reischütz n. sp.

Figs 1A, 2

Material examined. Holotype: Thailand, Surat Thani Province, Ang Thong Islands, Wua Talap Island, ascent to

Buaboke Cave, 9°37.993’N, 99°40.369’E, ca. 50 m a.s.l. (locality code: Th1), Sep. 2007, A. Reischütz leg., at base

of limestone rocks, NHMW 113484 (D: 2.03 mm, H: 1.23 mm). Paratype: 1 shell, same data as holotype, RE.

Etymology. The specific epithet (noun used in apposition) derives from the name of the cave where the new

species was collected.

Diagnosis. A tiny Chamalycaeus species with finely ribbed R1, elevated, narrow swelling on R3, and great

distance between inner and outer peristomes.

Description. Shell off-white, probably somewhat translucent when fresh; shell outline oval in dorsal view;

spire slightly elevated, low conical; body whorl rounded; protoconch low, finely granular, spiral striae lacking,

1.25–1.5 whorls; R1 of 1.25–1.5 whorls, with strong, elevated, slim, densely, regularly arranged ribs, fine spiral

striation between ribs; boundary between R1 and R2 distinct due to change of rib density; R2 ribs slightly curved

towards aperture, spaces between ribs approximately as wide or slightly wider than ribs; ca. 26 ribs present; R2+R3

less than quarter whorl (ca. 80˚), R2 somewhat shorter than R3; boundary between R2 and R3 distinct due to deep

constriction and ribless posterior portion of R3; R3 with short, narrow, ribbed central swelling; anterior slope of

swelling steeper than posterior slope; aperture oblique to shell axis, rounded with small basal incision; boundary

between inner and outer peristomes conspicuous, inner peristome strongly thickened, protruding, and slightly ex-

panded; outer peristome thin, strongly expanded, distinctly reflected portion over umbilicus; distance between inner

and outer peristomes significant, swelling of R3 and edge of outer peristome closely situated; umbilicus relatively

narrow, ca. one fourth of shell width.

Measurements. D: 2.03–2.29 mm, H: 1.23–1.33 mm.

Operculum. Unknown.

Differential diagnosis. The most similar species is Chamalycaeus canaliculatus (Möllendorff, 1894) (exam-

ined material: Golf von Siam: Koh-Samui, coll. Möllendorff, SMF 109468, lectotype, Fig. 1B), which was described

from the nearby island, Koh Samui. The new species from Wua Talap Island is slightly smaller (C. canaliculatus D:

2.4 mm), has a more elevated R3, and much greater distance between the inner and outer peristomes.

The new species differs from Dicharax ovatus n. sp. by the slightly smaller size, lower spire, very rounded body

whorl and aperture, blunt swelling on R3, and the shorter distance between the inner and outer peristomes.

Distribution. This new species is known only from the type locality (Fig. 3).

PÁLL-GERGELY ET AL.

FIGURE 1. Shells of Chamalycaeus Möllendorff, 1897 species. A: Chamalycaeus buaboke Páll-Gergely & A. Reischütz, n. sp.,

holotype (NHMW 113484); B: Chamalycaeus canaliculatus (Möllendorff, 1894), lectotype (SMF 109468).

FIGURE 2. SEM images of Chamalycaeus buaboke Páll-Gergely & A. Reischütz, n. sp., holotype (NHMW 113484). A: proto-

conch; B: R2 ribs; C: frontal view of the body whorl; D: ventral view of the body whorl.

PÁLL-GERGELY ET AL.

FIGURE 3. Distribution of alycaeid species in southern Thailand. Filled triangle: Dicharax ovatus Páll-Gergely & Auffenberg,

n. sp., inverted filled triangle: Dicharax subroseus Páll-Gergely, n. sp., inverted empty triangles: Chamalycaeus irmatallus

Páll-Gergely, n. sp., empty circles: C. krabiensis Páll-Gergely & A. Reischütz, n. sp., filled circle: Chamalycaeus serratus

Páll-Gergely & Auffenberg, n. sp., empty triangles: Chamalycaeus hirpex Páll-Gergely & A. Reischütz, n. sp., filled square:

Chamalycaeus buaboke Páll-Gergely & A. Reischütz, n. sp.

Chamalycaeus erawan Páll-Gergely & Hunyadi n. sp.

Fig. 4

Material examined. Holotype: Thailand, Kanchanaburi Province, Erawan National Park, Erawan Falls Trail,

14°22.310’N, 99°8.699’E, 90 m a.s.l. (locality code: 2015/28), 17 Feb. 2015, A. Hunyadi leg., HNHM 104869 (D:

2.45 mm, H: 1.53 mm). Paratypes: 4 shells, same data as for holotype, HA; 1 shell, Thailand, Kanchanaburi Prov-

ince, 4.3 km SW Kanchanaburi, Taoist Buddhist temple, 13°59’N, 99°31’E, 40 m a.s.l., 13 May 1988, K. Auffen-

berg leg., litter sample, UF 345935.

Etymology. The specific epithet refers to the type locality (Erawan National Park).

Diagnosis. A small Chamalycaeus species with bluntly angled body whorl, short R2, rounded aperture, and

strongly expanded outer peristome.

Description. Shell off-white to light grey, rather glossy, very slightly translucent; shell outline slightly oval in

dorsal view; spire slightly elevated, conical-domed; body whorl rather bluntly angled, depressed inward basolater-

ally in apertural view; protoconch rather low, glossy, spiral striae lacking, 1.25–1.5 whorls; R1 of 1.5–1.75 whorls,

with irregular, narrow, but rather low ribs and some weak spiral striation; boundary between R1 and R2 not distinct,

but visible due to change in rib density; R2+R3 approximately a quarter whorl; R2 short, about one third of R3

length, only ca. 14–16 ribs; R2 ribs low, dorsally rounded; boundary between R2 and R3 distinct due to moderately

deep constriction and almost smooth early R3; R3 with elongated, almost smooth (only a few low riblets/growth

lines) central swelling; aperture oblique to shell axis, round; distance between inner and outer peristomes conspicu-

ous, inner peristome protruding, thin, but robust, and slightly expanded; outer peristome strongly expanded, but not

reflected, reduced in umbilical area; umbilicus narrow, less than one third shell width.

Measurements. D: 2.25–2.45 mm, H: 1.49–1.56 mm.

Operculum. Unknown.

Differential diagnosis. This new species differs from Chamalycaeus irmatallus n. sp. in the larger size, longer

R3, and more expanded peristome.

Distribution. This species is known only from two nearby localities (Fig. 5).

FIGURE 4. Chamalycaeus erawan Páll-Gergely & Hunyadi, n. sp., holotype (HNHM 104869).

PÁLL-GERGELY ET AL.

FIGURE 5. Distribution of alycaeid species. Inverted empty triangle: Dicharax cyclostoma Páll-Gergely, n. sp., empty triangle:

Chamalycaeus spiratus Páll-Gergely, n. sp., filled triangle: Metalycaeus bicarinatus Páll-Gergely & Hunyadi, n. sp., inverted

filled triangles: Chamalycaeus erawan Páll-Gergely & Hunyadi n. sp., empty circles: Metalycaeus aries Páll-Gergely & Auffen-

berg, n. sp., filled circles: Metalycaeus heudei (Bavay & Dautzenberg, 1900) (the one in the north indicates the type locality of

Alycaeus kengtungensis Godwin-Austen, 1914), square: Metalycaeus pygmachos Páll-Gergely & Hunyadi, n. sp.

Chamalycaeus hirpex Páll-Gergely & A. Reischütz n. sp.

Figs 6–8

Material examined. Holotype: Thailand, Krabi Province, N of Krabi, Wat Tham Suea (Tiger Cave Temple), along

steps to the cave, 8°7.603’N, 98°55.466’E, ca. 90 m a.s.l. (locality code: Th11), Sep. 2007, A. Reischütz leg., at base

of limestone rocks, NHMW 113485 (D: 2.42 mm, H: 1.53 mm). Paratypes: 12 shells, same data as holotype, RE;

42 shells, Thailand, Krabi Province, Railay Beach West, Viewpoint Hill, 8°0.511’N, 98°50.248’E, ca. 30 m a.s.l.

(locality code: Th14), Sep. 2007, A. Reischütz leg., at base of limestone rocks, RE; 2 shells, same data as preceding,

CUMZ 5268; 1 shell (Fig. 6C), Thailand, Krabi Province, E of Krabi, Khao Khanab Nam limestone hill, 8°4.707’N,

98°55.263’E, ca. 2 m a.s.l. (locality code: Th15), Sep. 2007, A. Reischütz leg., at base of limestone rocks just above

tidal influence, NHMW 113486; 17 shells, same data as preceding, RE; 3 shells, limestone hill at river Khanab

Nam (Krabi Yai) at the northeastern city limits of Krabi, by the road Thanon Lan Gu (Mueang Kao), ca. 400 m E

of crossing with road Thanon Thong Chai, S of road, 8°5.817’N, 98°55.068’E, ca. 10 m a.s.l. (locality code: Th17),

Mar. 2010, A. Reischütz leg., at base of limestone rocks, RE; 2 shells, Thailand, Krabi Province, Wat Tham Sua,

8°7.567’N, 98°55.496’E, 40 m a.s.l. (locality code: 2015/34), 21 Feb. 2015, A. Hunyadi leg., HA. Other material:

7 juvenile/broken shells; same data as holotype, RE; 6 juvenile/broken shells, Thailand, Krabi Province, Railay

Beach West, Viewpoint Hill; 8°0.511’N, 98°50.248’E; ca. 30 m a.s.l. (locality code: Th14), Sep. 2007, A. Reischütz

leg., at base of limestone rocks, RE; 4 juvenile/broken shells, Thailand, Krabi Province, E of Krabi, Khao Khanab

Nam limestone hill, 8°4.707’N, 98°55.263’E, ca. 2 m a.s.l. (locality code: Th15), Sep. 2007, A. Reischütz leg., at

base of limestone rocks just above tidal influence, RE; 2 juvenile/broken shells, Thailand, Krabi Province, limestone

hill at river Khanab Nam (Krabi Yai) at northeastern city limits of Krabi, by road Thanon Lan Gu (Mueang Kao),

ca. 400 m E of crossing with road Thanon Thong Chai, S of road, 8°5.817’N, 98°55.068’E, ca. 10 m a.s.l. (locality

code: Th17), Mar. 2010, A. Reischütz leg., at base of limestone rocks, RE; 3 juvenile/broken shells, Thailand, Krabi

Province, Wat Tham Sua, 8°7.567’N, 98°55.496’E, 40 m a.s.l. (locality code: 2015/34), 21 Feb. 2015, A. Hunyadi

leg., HA; 2 broken shells, Thailand, Krabi Province, granite rock in evergreen forest at Tone Nga Chang Waterfall,

Cha Lung, Hat Yai, Songkhla, 6°56.810’N, 100°13.895’E (locality code: AC21), C. Sutcharit et al. leg., CUMZ

5271 (Fig. 8, identification questionable, not shown on Fig. 3).

Etymology. The specific epithet refers to the R2 rib morphology, which, with the numerous tooth-like projec-

tions, is reminiscent of a harrow, an agricultural tool consisting of a framework with teeth used to break up plowed

land (hirpex in Latin).

Diagnosis. A small Chamalycaeus species with R2+R3 shorter than a quarter whorl and R2 with serrulate ribs.

Description (based on the type series). Shell off-white, light grey to slightly yellowish; shell outline rounded

in dorsal view, R2 conspicuously bulging/angled in dorsal view, but variable in some populations; spire rather de-

pressed, but variable among populations, low conical; body whorl rounded or rather parabolic; protoconch elevated,

finely granular, spiral striation lacking, 1.5 whorls (Figs 7C–D); R1 ca. 1.5 whorls, first ca. 0.75 whorl dominated by

fine ribbing that gradually increases strength toward the R1 termination; spiral striation as strong as radial ribs at end

of R1, while due to domination of ribs at end of R1, relative strength of spiral striae decreases; R1 and R2 boundary

conspicuous due to denser R2 ribs; R2+R3 less than a quarter whorl (ca. 70–80˚); R2 bulging, forming a blunt angle

in dorsal view, and rounded in apertural view; R2 ribs lamella-like, rather low, characteristically serrate (i.e. a series

of tiny spikes pointing anteriorly, see Figs 7A–B), ca. 24–26 R2 ribs present; R2 and R3 of comparable lengths or

R2 slightly shorter; R3 with spiral striation and weaker ribs than R1; boundary between R2 and R3 distinct due

to lower R3 ribs, although constriction is shallow; aperture very strongly oblique to shell axis; rounded, with very

weak upper (parieto-palatal) incision, a weak basal incision occasionally also indicated; boundary between inner

and outer peristomes distinct; inner peristome protruding, rather sharp and relatively thin; outer peristome expanded

except in umbilical area; umbilicus relatively wide, over one third shell width.

A cross-sectional view of R2 was examined in one specimen (Figs 7E–H): anterior crust forms an elevated rib,

which forms a series of hollow spikes (visible in cross-sectional image as widened tip) toward aperture, posterior

crust low, adnate to anterior crust, which slightly folds over posterior crust; cross-sectional view of microtunnels

nearly rounded, drop shaped, or somewhat triangular.

Measurements. D: 2.00–2.61 mm, H: 1.32–1.67 mm.

Operculum. Strongly concave, outer surface with no structures, covered with thick mud layer; inner side with

elevated central nipple (Fig. 6B).

PÁLL-GERGELY ET AL.

Differential diagnosis. The reticulated R2 sculpture distinguishes this species from all congeners except for C.

serratus n. sp. See that species for comparisons.

Distribution. This new species is known from four populations occurring in Krabi Province, Thailand (Fig. 3).

Remarks. The examined populations show a degree of morphological variability, see Table 1.

TABLE 1. Variation of shell characters of Chamalycaeus hirpex Páll-Gergely & A. Reischütz, n. sp.

shell diameter (in mm) spire R2

Th15 2.00–2.27 more elevated normally developed

Th11, 2015/34 2.4–2.61 more depressed bulging, angled in dorsal view

Th17 more elevated normally developed

Th14 more elevated bulging, angled in dorsal view

FIGURE 6. Chamalycaeus hirpex Páll-Gergely & A. Reischütz, n. sp. A: holotype (NHMW 113485); B: operculum, paratype

from the type locality (site Th11, sp3); C: paratype (site Th15 NHMW 113486).

FIGURE 7. Chamalycaeus hirpex Páll-Gergely & A. Reischütz, n. sp. A–D: holotype (NHMW 113485); E–H: paratype from

the type locality (RE). Abbreviations: a—anterior crust; p—posterior crust; t—microtunnel.

PÁLL-GERGELY ET AL.

FIGURE 8. Chamalycaeus cf. hirpex Páll-Gergely & A. Reischütz, n. sp. CUMZ 5271.

Chamalycaeus irmatallus Páll-Gergely n. sp.

Figs 9, 10A

Material examined. Holotype: Thailand, Surat Thani Province, limestone mtn., 6 km S of Na San, 8°39.583’N,

99°23.883’E, 100 m a.s.l., 3 Jun. 1987, F.G. Thompson leg., UF 279508 (D: 2.02 mm, H: 1.32 mm). Paratypes:

11 shells, same data as holotype, UF 551216. Other material: 6 shells, Myanmar, Thayet-myo, Pegu, coll. Blan-

ford, NHMUK 1906.4.4.71; 1 shell, Thailand, Phang Nga Province, Phang Nga, Tham Nam Phud, 8°27.829’N,

98°32.617’E, 40 m a.s.l. (locality code: 2015/33), 20 Feb. 2015, A. Hunyadi leg., around the cave, HA.

Etymology. The specific epithet is an anagram for armillatus, a species with which this new species has been

confused (see Differential diagnosis).

Diagnosis. A tiny Chamalycaeus species with glossy shell, irregularly, finely ribbed R1, very short R2 with

blunt, low ribs, and somewhat longer R3 (the two latter regions are shorter than a quarter whorl combined).

Description. Shell off-white, rather glossy, although available shells are somewhat eroded; shell outline slight-

ly oval in dorsal view; spire slightly elevated, conical-domed; body whorl somewhat “parabolic” in apertural view;

protoconch rather low, glossy, spiral striae lacking, 1.25 whorls; R1 of 1.5–1.75 whorls, with very indistinct, ir-

regular, low and rounded, relatively wide ribs, and some weak spiral striation; boundary between R1 and R2 distinct

due to change in intensity and strength of ribbing; R2 short, only ca. 16–20 ribs; R2+R3 less than quarter whorl

(ca. 70–80˚); R3 up to twice as long as R2; boundary between R2 and R3 clear due to change in rib morphology,

although constriction very shallow; R3 with very fine, rounded ribs, and low, convex, elongated central swelling;

aperture round, slightly oblique to shell axis; boundary between inner and outer peristomes distinct, inner peristome

strongly protruding, thickened, slightly expanded; outer peristome slightly weaker or as strong, also expanded, only

slightly reflected toward umbilicus; umbilicus relatively narrow, ca. one third of shell width.

Measurements. D: 1.75–2.02 mm, H: 1.15–1.32 mm.

Operculum. Unknown.

Differential diagnosis. Chamalycaeus armillatus (Benson, 1856) (material examined: Thayet-Mio, UMZC

102995, holotype, Fig. 10B) has a more rounded body whorl, longer R2 and R3, and a thicker peristome with greater

distance between the edges of the inner and outer peristomes.

Distribution. The type locality is in Thailand’s Surat Thani Province. A single shell was collected in the neigh-

bouring Phang Nga Province (locality code: 2015/33, coll. HA). Shells collected more than 1,000 km north in

Thayet, Myanmar are so similar to the Thai populations that they could not be separated (see below) (Fig. 3).

Remarks. Chamalycaeus armillatus was described from an eroded specimen. Some spiral striations are visible

on the holotype, but they might be the part of the lower shell layer. Thus, this species was provisionally assigned to

Chamalycaeus in Páll-Gergely et al. (2020).

Specimens from Thayet (NHMUK 1906.4.4.71, labelled as armillatus) have slightly less densely arranged R2

ribs than typical C. irmatallus n. sp.

A single, eroded shell from Tham Nam Phud (Thailand) is somewhat larger than the holotype of C. irmatallus

n. sp., and has a longer R2. Since all other shell characters are identical, we provisionally identify the Tham Nam

Phud and Thayet specimens as C. cf. irmatallus n. sp.

FIGURE 9. Chamalycaeus irmatallus Páll-Gergely, n. sp. A: holotype (UF 279508); B: paratype (UF 551216).

PÁLL-GERGELY ET AL.

FIGURE 10. Shells of Chamalycaeus Möllendorff, 1897 species. A: Chamalycaeus irmatallus Páll-Gergely, n. sp., NHMUK

1906.4.4.71; B: Chamalycaeus (?) armillatus (Benson, 1856), holotype (UMZC 102995).

Chamalycaeus krabiensis Páll-Gergely & A. Reischütz n. sp.

Fig. 11

Material examined. Holotype: Thailand, Krabi Province, Phi-Phi Islands, Phi Phi Don Island, climbing rock at W

end of beach in Ton Sai Bay, 7°44.011’N, 98°45.936’E, ca. 70 m a.s.l. (locality code: Th22), Mar. 2010, A. Reis-

chütz leg., at base of limestone rocks in the forest, NHMW 113487 (D: 3.61 mm, H: 2.62 mm). Paratypes: 1 shell,

same data as holotype; 1 shell, Thailand, Krabi Province, Phi-Phi Islands, Phi Phi Don Island, ascent to climbing

rock at W end of beach in Ton Sai Bay, 7°44.049’N, 98°45.966’E, ca. 20 m a.s.l. (locality code: Th21), Mar. 2010,

A. Reischütz leg., at base of limestone rocks in forest, NHMW 113488 (photographed paratype: Fig. 11B, D: 3.73

mm, H: 2.37 mm); 9 shells, same data as preceding, RE; 2 shells, same data as preceding, CUMZ 5269; 7 shells,

Thailand, Krabi Province, Phi-Phi Islands, Phi Phi Don Island, limestone rocks at Monkey Beach, 7°43.386’N,

98°46.135’E, ca. 10 m a.s.l. (locality code: Th23), Mar. 2010, A. Reischütz leg., RE. Other material: 4 juvenile/

broken shells, Thailand, Krabi Province, Phi-Phi Islands, Phi Phi Don Island, ascent to climbing rock at W end of

beach in Ton Sai Bay, 7°44.049’N, 98°45.966’E, ca. 20 m a.s.l. (locality code: Th21), Mar. 2010, A. Reischütz leg.,

at base of limestone rocks in forest, RE; 5 juvenile/broken shells, Thailand, Krabi Province, Phi-Phi Islands, Phi Phi

Don Island, limestone rocks at Monkey Beach, 7°43.386’N, 98°46.135’E, ca. 10 m a.s.l. (locality code: Th23), Mar.

2010, A. Reischütz leg., RE; 7 shells, 1.5 km SE of Ao Luek Tai, 8°22.386’N, 98°44.130’E, 40–45 m a.s.l., 16–19

Mar. 2020, S. Aiken leg., SA; 4 shells (one photographed here: Fig. 11C), 1.7 km SE of Ao Luek Tai, 8°22.020’N,

98°44.004’E, 25 m a.s.l., 19 Mar. 2020, S. Aiken leg., in dry debris on rock, at base of limestone cliff, SA.

Etymology. This new species is named for the Thai province in which it occurs.

Diagnosis. A medium-sized Chamalycaeus species with R2 and R3 of almost a quarter whorl each, blunt, elon-

gated swelling on R3, protruding inner peristome, and strongly expanded outer peristome.

Description. Shell off-white to light grey; shell outline slightly oval in dorsal view; spire elevated, conical;

body whorl rounded or parabolic; protoconch somewhat elevated, finely granular, rather glossy, spiral striae lack-

ing, 1.5 whorls; R1 of 1.75–2.5 whorls, with strong, narrow, elevated, regularly arranged ribs, spaces between ribs

relatively wide, fine spiral striation between ribs; boundary between R1 and R2 distinct due to change in rib density;

R2 ribs more elevated than those of R1, narrow, lamella-like; ca. 26–28 ribs present; R2 and R3 of comparable

lengths, covering approximately a half whorl or slightly less; boundary between R2 and R3 distinct due to rather

deep constriction and change in sculpture; R3 with elongated, convex, central swelling, posterior portion almost

smooth, anterior bears ribs of similar density as on R1; aperture strongly oblique to shell axis, rounded, with a very

small upper (parieto-palatal) incision; boundary between inner and outer peristomes conspicuous, inner peristome

strongly protruding (extreme in some specimens) and slightly expanded; outer peristome slim, strongly expanded

except in umbilical region; umbilicus narrow, ca. one fourth of shell width.

Measurements. D: 3.41–3.81 mm, H: 2.34–2.62 mm (type samples).

Operculum. Unknown.

Differential diagnosis. Chamalycaeus reinhardti (Mörch, 1872) (examined material: Great Nicobar, coll. God-

win-Austen, NHMUK 1903.7.1.2711, 1 shell) and Chamalycaeus reinhardti sabangensis (Rensch, 1933) (examined

material: Sumatra: Wald b. Sabang, Pulu Weh., exp. Rensch, 1927, SMF 6241, 1 paratype) both have a narrower

swelling on R3 and a more elevated spire.

Distribution. This species is known from the Phi-Phi Islands and the vicinity of Ao Luek Tai town, Krabi

Province, Thailand (Fig. 3).

Remarks. The shells from the two sites near Ao Luek Tai are slightly smaller (D: 2.8–3.3 mm), more depressed

and conical from above, have overall denser ribs, lower R3 swelling, and the outer peristome is expanded in a

smaller portion of the lip. However, although these differences occur, we consider them conspecific with those from

Phi-Phi Islands due to the overall similar sculpture and proportions of shell regions.

PÁLL-GERGELY ET AL.

FIGURE 11. Chamalycaeus krabiensis Páll-Gergely & A. Reischütz, n. sp. A: holotype (site Th22, NHMW 113487); B: para-

type (site Th21, NHMW 113488); C: Krabi Province, 1.7 km SE of Ao Luek Tai, Simon Aiken leg., 19 Mar. 2020, coll. SA.

Chamalycaeus serratus Páll-Gergely & Auffenberg n. sp.

Fig. 12

Material examined. Holotype: Thailand, Nakhon Si Thammarat Province, Khao Luang Park, 15.2 km S junction

Highways 4186 and 4188, 1.3 km S Park Headquarters, 8°44’N, 99°43’E, 200 m a.s.l., 16 Apr. 1988, K. Auffenberg

leg., UF 345204 (D: 2.35 mm, H: 1.67 mm).

Etymology. Named for the serrated R2 ribs (Latin derivative serratus, notched like a saw).

Diagnosis. A small Chamalycaeus species with R2+R3 being longer than a quarter whorl, R3 twice as long as

R2, which bears characteristically serrulate R2 ribs.

FIGURE 12. Chamalycaeus serratus Páll-Gergely & Auffenberg, n. sp., holotype (UF 345204).

Description. Shell off-white, although dead-collected; shell outline rounded/slightly oval in dorsal view; spire

elevated, conical; body whorl rounded with some depression inwardly in dorso-basal region; protoconch 1.5 whorls,

elevated, finely granular, without spiral striation; R1 slightly more than 1.5 whorls, first ca. 0.75 whorl dominated

by fine ribs, gradually becoming stronger toward R1 termination; spiral striation as strong as radial ribs at R1 ter-

mination; boundary between R1 and R2 conspicuous because of denser R2 ribs; R2+R3 more than quarter whorl

PÁLL-GERGELY ET AL.

(approximately 100˚); R2 ribs lamella-like, rather low, characteristically serrate with series of tiny spikes pointing

anteriorly, ca. 28 R2 ribs present; R3 ca. twice as long as R2; R3 with rather strong spiral striation and weaker ribs

than R1; boundary between R2 and R3 clear due to less pronounced R3 ribs, although constriction is shallow; aper-

ture strongly oblique to shell axis, rounded; boundary between inner and outer peristomes distinct; inner peristome

protruding, narrow, and relatively thin; outer peristome expanded, especially in basal and upper palatal directions;

umbilicus narrow, ca. one fourth of shell width.

Measurements. D: 2.35 mm, H: 1.67 mm.

Operculum. Unknown.

Differential diagnosis. This new species is very similar to Chamalycaeus hirpex n. sp. in terms of R2 mor-

phology. However, it differs from that species in the long R3, which has an elongated, blunt swelling, and a more

expanded aperture.

Distribution. This new species is known only from the type locality (Fig. 3).

FIGURE 13. Chamalycaeus spiratus Páll-Gergely, n. sp., holotype (UF 279157).

Chamalycaeus spiratus Páll-Gergely n. sp.

Fig. 13

Material examined. Holotype: Thailand, Rayong Province, limestone range Khao San Ta, 2.0 km W of Ban Syaek

Batan, 12°58.75’N, 101°40.00’E, 150 m a.s.l., 25 Apr. 1987, F.G. Thompson leg., UF 279157 (D: 1.8 mm, H: 1.16

mm). Paratypes: 5 shells, same data as holotype, UF 551217.

Etymology. This new species is named for its conspicuous spiral striae.

Diagnosis. A tiny Chamalycaeus species with strong, conspicuous spiral striations on entire teleoconch, R2+R3

slightly shorter than a quarter whorl, and distance between the edges of the inner and outer peristomes is great, outer

peristome not reflected.

Description. Shell off-white to yellowish-corneous, probably somewhat translucent when fresh; shell outline

rounded in dorsal view; spire slightly elevated, low conical; body whorl rounded; protoconch somewhat elevated,

glossy, finely granular, spiral striae lacking, 1.5 whorls; R1 of 1.25–1.5 whorls, with very strong, broad spiral striae

on last 0.75–1.0 whorl, preceding area rather smooth; last ca. half whorl of R1 with strong but low ribs, similar

strength to spiral striae, widely and irregularly spaced; boundary between R1 and R2 distinct due to change in rib

density; R2 ribs curve toward aperture, spaces between ribs approximately as wide as ribs; ca. 18–20 ribs present;

R2+R3 less than quarter whorl (ca. 70–80˚), comparable in length; boundary between R2 and R3 distinct due to

change in rib morphology, constriction lacking; R3 practically without swelling, with similar spiral striae to that of

R1, ribs virtually absent, replaced by very fine, weak growth lines; aperture slightly oblique to shell axis, round;

boundary between inner and outer peristomes conspicuous, inner peristome strongly protruding and slightly ex-

panded; edge of outer peristome thin, expanded weakly toward umbilicus, not reflected; umbilicus relatively nar-

row, approximately one third of shell width.

Measurements. 1.72–1.93 mm, H: 1.07–1.16 mm.

Operculum. Unknown.

Differential diagnosis. The small size, prominent, thin outer peristome, strong ribs and spiral striae distinguish

this species from all other congeners. The most similar species in size and sculpture are Chamalycaeus microco-

nus (Möllendorff, 1887) (examined material: Malakka: Bukit Pondong (Perak), SMF 109493, lectotype, and SMF

109494, 2 paralectotypes) and Chamalycaeus mixtus Zilch, 1957 (examined material: Malakka: Bukit Pondong

(Perak), SMF 109510, holotype, and SMF 109511, 4 paratypes) from the Malay Peninsula (Bukit Pondong), but

they have higher spires, comparatively larger apertures, and shorter R3s. For comparisons, see photos in Páll-

Gergely et al. (2020).

Distribution. This new species is known only from the type locality (Fig. 5).

Genus Dicharax Kobelt & Möllendorff, 1900

Charax Benson, 1859: 177.

Dicharax Kobelt & Möllendorff, 1900: 186. (replacement name for Charax Benson, 1859, non Charax Scopoli, 1777 [Pi-

sces]).

Type species. Alycaeus hebes Benson, 1857, by subsequent designation (Gude 1921).

Diagnosis. Typical Dicharax species possess R2 ribs curved toward aperture. Genus generally characterized by

complete absence of spiral striation. Only two of 164 species assigned to genus by Páll-Gergely et al. (2020), have

indication of spiral striation. A few other species reported to have striations by Jirapatrasilp et al. (2021). Despite

occurrence of spiral striations in relatively few species, the absence of striations is generally a valuable character by

which to recognize Dicharax species, although examination of additional characters is also critical.

Dicharax (?) admirandus Páll-Gergely & Auffenberg n. sp.

Figs 14–15

Material examined. Holotype: Thailand, Loei Province, 9.2 km NW Loei, Buddhist temple, up and N of main cave

entrance, 17°35’N, 101°44’E, 250 m a.s.l., 28 Apr. 1988, K. Auffenberg leg., base of cliff under Georissa zone, UF

345861 (D: 2.9 mm, H: 1.9 mm). Paratype: 1 shell, same data as holotype, UF 551218.

PÁLL-GERGELY ET AL.

FIGURE 14. Dicharax admirandus Páll-Gergely & Auffenberg, n. sp., holotype (UF 345861).

Etymology. The specific epithet admirandus (Latin for astonishing, remarkable, extraordinary) refers to several

notable shell characters of this new species, namely the strong keel, strongly fringed aperture, and the spiral stria-

tion.

Diagnosis. A medium-sized Dicharax species with strong peripheral keel, strongly ribbed and spirally striated

R1, and strongly fringed aperture.

Description. Shell off-white, although both available shells were somewhat eroded; shell outline slightly oval

in dorsal view; spire slightly elevated, low conical, body whorl with conspicuous peripheral keel; protoconch some-

what elevated, finely granular, spiral striation lacking, 1.75 whorls; R1 of 1.5 whorls, first half whorl practically

smooth, gradually changing to widely, regularly-spaced, strong ribs (ca. 30 ribs on last half whorl of R1), present

on entire R1 except area between peripheral keel and outer edge of periumbilical keel, which has fine spiral stria-

tion; some spiral striation visible on dorsum of R1, and between ribs; boundary between R1 and R2 distinct due to

dense R2 ribs; R2 ribs curved toward aperture, ca. 34–36 R2 ribs present; spaces between R2 ribs narrower than

ribs; R2+R3 more than quarter whorl (ca. 110˚); R2 considerably shorter than R3, slightly more half its length;

boundary between R2 and R3 distinct due to change in sculpture and deep constriction; R3 with rounded, elongated

swelling situated closer to constriction than to peristome; aperture strongly oblique to shell axis, rounded with basal

incision; boundary between inner and outer peristomes not conspicuous; inner peristome strong, somewhat protrud-

ing, expanded, basal and palatal portions strongly fringed, outer peristome weaker, expanded, but reflected only in

direction of umbilicus; umbilicus funnel-shaped, relatively narrow, less than one third of shell width.

FIGURE 15. Sculpture of Dicharax admirandus Páll-Gergely & Auffenberg, n. sp., holotype (UF 345861).

Measurements. D: 2.9–3 mm, H: 1.9 mm

Operculum. Unknown.

Differential diagnosis. The angled body whorl, the funnel-shaped umbilicus, the flattened dorsal side, and

the strongly convex R3 swelling distinguish this new species from the most similar D. fimbriatus (Bavay & Daut-

zenberg, 1912), which is known from Laos and Vietnam (Páll-Gergely et al. 2017). The R1 ribs of this species are

stronger than those of most D. fimbriatus populations, and the new species has a spirally striated R1.

Dicharax sylheticus (Godwin-Austen, 1914) (Examined material: S. Sylhet Hills, W. Channel leg., NHMUK

1903.7.1.55, holotype, Fig. 16) is similar, but has a more elevated spire, a less keeled body whorl, a longer R2 with

less dense ribs, and a rounded aperture.

Distribution. This new species is known only from the type locality (Fig. 17).

Remarks. Similarly to some populations of D. omissus (Godwin-Austen, 1914), this species also possesses spi-

ral striation on R1, which is very rare in Dicharax. Spiral striation on the teleoconch is characteristic for Chamaly-

caeus, but this species is classified in Dicharax due to the curved R2 ribs characterizing that genus and its overall

shell shape. Possible homology of the spiral striation of these few Dicharax species and other alycaeid genera needs

further investigation.

PÁLL-GERGELY ET AL.

FIGURE 16. Dicharax sylheticus (Godwin-Austen, 1914), holotype (NHMUK 1903.7.1.55).

FIGURE 17. Distribution of alycaeid species in northern Thailand and Myanmar. filled circle: Dicharax admirandus Páll-

Gergely & Auffenberg, n. sp., empty square: Dicharax ebrius Páll-Gergely & Auffenberg, n. sp., filled triangle: Dicharax

gnomus Páll-Gergely, n. sp., filled square: Dicharax mirounga Páll-Gergely, n. sp., inverted empty triangles: Dicharax verruco-

sus Páll-Gergely & Hunyadi n. sp., rhombus: Dicharax stuparum Páll-Gergely & Hunyadi, 2018, empty triangle: Metalycaeus

anas Páll-Gergely & A. Reischütz, n. sp.

Dicharax ataranensis (Godwin-Austen, 1914)

Fig. 18

Alycæus ataranensis Godwin-Austen, 1914: 426, plate 148, figs 4, 4a–b.

Alycæus (Dicharax) ataranensis — Gude 1921: 237.

Dicharax ataranensis — Páll-Gergely et al. 2020: 77, fig. 18.

Material examined. Holotype: Myanmar, Ataran, Burma, ex Dr. F. Stoliczka, NZSI M.8073 (holotype [single

specimen mentioned in original description]). Other material: 1 shell, Myanmar, Kayin State, Mudon centre ESE

ca. 51 km, Htimahto NE, NE point of Kwooprai Hill, 16°2.396’N, 97°58.200’E, 30 m a.s.l. (locality code: 2018/47),

10 Oct. 2018, A. Hunyadi, K. Okubo & J.U. Otani leg., HA.

FIGURE 18. Dicharax ataranensis (Godwin-Austen, 1914). Myanmar, Kayin State, Mudon centre ESE ca. 51 km, Htimahto

NE, NE point of Kwooprai Hill, 30 m a.s.l. 16°2.396’N, 97°58.200’E (locality code: 2018/47), leg. A. Hunyadi, K. Okubo &

J.U. Otani, 10 Oct. 2018, HA.

PÁLL-GERGELY ET AL.

Type locality. “1 Ataran”.

Diagnosis (emended based on a newly collected specimen). Protoconch relatively low, glossy, without spiral

striation; R1 glossy, widely-spaced ribs near the suture and inside the umbilicus, edge of R1 smooth; R2+R3 over

a quarter whorl long, R2 ca. half as long as R3; R2 ribs typical for Dicharax (curved towards the aperture); R3

smooth, with blunt, but large, conspicuous, elevated swelling.

Remarks. Until recently the eroded holotype was the only known specimen of the species making the as-

signment to Dicharax questionable. The newly collected fresh shell allowed examination of shell sculpture which

confirmed the assignment.

Dicharax cyclostoma Páll-Gergely n. sp.

Fig. 19

Material examined. Holotype: Thailand, Nakhon Ratchasima Province, 3.4 km W of Ban Mu Si, limestone hill,

14°32.016’N, 101°22.783’E, 380 m a.s.l., 5 May 1987, F.G. Thompson leg., UF 346812 (D: 2.54 mm, H: 1.54 mm).

Paratypes: 18 shells, same data as holotype, UF 551219. Other material: 2 juvenile shells, same data as holotype,

UF 551220.

FIGURE 19. Dicharax cyclostoma Páll-Gergely n. sp., holotype (UF 346812).

FIGURE 20. Shells of Dicharax Kobelt & Möllendorff, 1900 species. A: Dicharax (?) bifrons (Theobald, 1870), syntype

(NHMUK 1888.12.4.956-958); B: Dicharax (?) woodthorpei (Godwin-Austen, 1914), syntype (NHMUK 1903.7.1.3064); C:

Dicharax politus (W.T. Blanford, 1865), probable syntype (NHMUK 1906.4.4.178).

PÁLL-GERGELY ET AL.

Etymology. This species is named for the very round aperture (Greek cyclo-, ring and stoma, mouth, opening,

noun in apposition).

Diagnosis. A small, depressed Dicharax species with glossy R1, protruding inner peristome, and round aper-

ture; R2+R3 shorter than a quarter whorl, R2 half as long as R3.

Description. Shell white, some specimens with very faint brownish or yellowish colouration; shell outline

rounded or very slightly oval in dorsal view, shell depressed, spire only slightly elevated, body whorl rounded; proto-

conch low, glossy, 1.25–1.5 whorls; R1 of 1.25–1.75 whorls, glossy without sculptural elements; boundary between

R1 and R2 conspicuous due to R2 ribs; R2 with ribs curved towards aperture, ca. 24–26 ribs present; spaces between

R2 ribs narrower than ribs; R2+R3 less than quarter whorl (ca. 80˚); R2 half or less length of R3; R3 glossy, smooth;

boundary between R2 and R3 distinct due to change in sculpture and moderately deep constriction; middle of R3

with rounded swelling; aperture strongly oblique to shell axis, round; boundary between inner and outer peristomes

not conspicuous; inner peristome somewhat protruding, rather slim, outer peristome multi-layered, thickened and

expanded, particularly toward umbilicus, but not reflected; umbilicus wide, slightly more than a third of shell width.

Measurements. D: 2.22–2.68 mm, H: 1.31–1.56 mm.

Operculum. Unknown.

Differential diagnosis. Dicharax politus (W.T. Blanford, 1865) (examined material: Phungdo, Arakan, coll.

Blanford, NHMUK 1906.4.4.178, 3 probable syntypes, Fig. 20C) is larger, has a more elevated spire, and longer R3.

Dicharax (?) immaculatus Páll-Gergely, 2017 from Gansu Province, China is similar with low spire and smooth R1,

but with shorter R2 without elevated ribs, and its peristome much thinner than that of new species. Some populations

of D. cristatus (Möllendorff, 1886) possess a smooth R1 and a low spire, but it has a longer R2, and is always larger

than the new species (Páll-Gergely et al. 2017).

Distribution. This new species is known only from the type locality (Fig. 5).

Dicharax ebrius Páll-Gergely & Auffenberg n. sp.

Fig. 21

Material examined. Holotype: Thailand, Mae Hong Son Province, 42 km NW of Pai, Road 1095, 19°32’N,

98°32’E, 750 m a.s.l., 20 Mar. 1988, K. Auffenberg leg., UF 345577 (D: 2.89 mm, H: 1.97 mm). Paratypes: 22

shells, same data as holotype, UF 551221. Other material: 9 juvenile shells, same data as holotype, UF 551222.

Etymology. The dorsal view of the shell of this new species looks like a face of a drunken (ebrius in Latin) man

due to glossy R3 swelling.

Diagnosis. A small Dicharax species with a finely ribbed R1, glossy swelling on R3 situated far from peri-

stome, thickened outer peristome and slightly fringed inner peristome.

Description. Shell off-white to yellowish corneous, slightly translucent; shell outline slightly oval in dorsal

view; spire slightly elevated, low conical, body whorl rounded; protoconch low, glossy, 1.25–1.5 whorls; R1 of

1.75–2 whorls, finely, regularly ribbed from beginning, ribs gradually become more widely-spaced toward R1

termination; boundary between R1 and R2 conspicuous due to dense R2 ribs; R2 ribs curved toward aperture, ca.

44–46 ribs present; R2 ribs almost adnate; R2+R3 slightly more than quarter whorl (ca. 100˚); R2 approximately

as long as R3 or slightly shorter; boundary between R2 and R3 distinct due to change in sculpture and deep con-

striction; R3 with prominent, but rounded, glossy swelling situated close to constriction; between swelling and

peristome with few fine ribs, in some specimens this area slightly swollen, seemingly forming secondary swelling;

aperture strongly oblique to shell axis, rounded with basal incision; boundary between inner and outer peristomes

indistinct; inner peristome strong, protruding, expanded, basal and palatal portions slightly fringed, outer peristome

expanded, and reflected toward umbilicus; peristome edges merge to form a multi-layered, thickened apertural lip;

umbilicus narrow, approximately one fourth of shell width.

Measurements. D: 2.65–2.89 mm, H: 1.85–1.97 mm.

Operculum. Outer surface concave, yellowish corneous, with some traces of a deciduous lamina; inner surface

with a small, pointed, low central nipple.

Differential diagnosis. The small shell size, blunt, but prominent, glossy swelling on R3 makes this new spe-

cies easy to recognize. Dicharax notus (Godwin-Austen, 1914) is similar in overall shell shape, but has blunter, less

glossy R3 swelling situated closer to peristome and a rounded aperture.

Due to the weak traces of lower, secondary R3 swelling and overall shell shape, this new species is similar to D.

birugosus (Godwin-Austen, 1893) (syn. Alycaeus canaliculus Godwin-Austen, 1914, see Páll-Gergely et al. 2020)

from the Khasi Hills, India. However, the Indian species has shorter R2 and R3, the R2 ribs are more widely-spaced,

and prominent secondary swelling.

Distribution. This new species is known only from the type locality (Fig. 17).

FIGURE 21. Dicharax ebrius Páll-Gergely & Auffenberg, n. sp., A: holotype (UF 345577); B: paratype (UF 551221).

Dicharax (?) gnomus Páll-Gergely n. sp.

Fig. 22

Material examined. Holotype: Thailand, Phrae Province, 4 km N of Ban Nim Rin, valley with limestone ridges,

18°10.133’N, 99°56.233’E, 200 m a.s.l., 16 May 1988, F.G. Thompson leg., leaf litter at base of boulders, UF

380401 (D: 1.65 mm, H: 1.15 mm).

PÁLL-GERGELY ET AL.

FIGURE 22. Dicharax (?) gnomus Páll-Gergely, n. sp., holotype (UF 380401).

Etymology. The specific epithet gnomus (Medieval Latin for gnome) refers to the tiny shell that has unusual

shell area ratios compared to most other species (to be used as a noun in apposition).

Diagnosis. Tiny Dicharax species with wide, flat R1 ribs and fine spiral striation, short R2 with flat ribs,

strongly reduced R3, and circular aperture.

Description. Shell light grey, slightly semi-translucent; shell outline rounded in dorsal view; spire slightly el-

evated, body whorl rounded; protoconch low, finely granular, glossy, 1.5 whorls; R1 of 1.25 whorls, beginning with

low ribs that appear curved anteriorly, developing into wide, flattened ribs separated by grooves, forming a smooth-

ish, glossy surface; first whorl of R1 with some fine spiral striation; boundary between R1 and R2 not conspicuous

due to similar rib morphology, although ribs become denser, ca. 30 R2 ribs present; R2+R3 less than quarter whorl

(ca. 70–80˚); R3 considerably shorter than R2; boundary between R2 and R3 distinct due to sculpture change and

rather deep constriction; R3 strongly reduced, represented only as a slight swelling just behind peristome; aperture

almost parallel with shell axis, circular, round; peristome weak, very slightly thickened; boundary between inner

and outer peristomes barely discernible; inner peristome weak, somewhat protruding and very slightly expanded,

outer peristome very weakly developed, only indicated; umbilicus relatively narrow, less than one third of shell

width.

Measurements. D: 1.65 mm, H: 1.15 mm.

Operculum. Unknown.

Differential diagnosis. The R3 region practically absent in this species. No other low-spired alycaeid species

has this trait in Thailand or Myanmar. The Dicharax species described as Awalycaeus Kuroda, 1951 in Japan also

have a strongly reduced R3, but we consider this is a case of convergent evolution.

Distribution. This new species is known only from the type locality (Fig. 17).

Remarks. This species has unusual conchological characters, and therefore, its generic placement is unclear.

The spiral striation on R1 and the lack of spiral striation on the protoconch suggests a relationship to Chamalycaeus,

whereas the glossy shell surface, the flattened R2 ribs, and the low protoconch indicate a position in Dicharax.

This study revealed other Dicharax species/populations that possess some spiral striae on R1 (see under Dicharax

admirandus, n. sp. and D. omissus and Páll-Gergely et al. 2017). Thus, the placement of this species in Dicharax

is justified.

Dicharax mirounga Páll-Gergely n. sp.

Fig. 23

Material examined. Holotype: Thailand, Tak Province, Knoll 7 km E of Ban Huei Hin Fond, 16°46.350’N,

98°40.383’E, 610 m a.s.l., 02 May 1987, F.G. Thompson leg., UF 347421 (D: 3.13 mm, H: 2.08 mm).

Etymology. The R3 shape of this species is reminiscent of the large proboscis of elephant seal males (genus

Mirounga) (see Galimberti et al. 2019).

Diagnosis. A medium-sized Dicharax species with glossy R1 having some widely-spaced, typical Dicharax-

ribs, long R3 with an elongated swelling, strongly expanded outer peristome, and narrow umbilicus.

Description. Shell white, with slightly yellowish colouration; shell outline oval in dorsal view; spire elevated,

conical, body whorl rounded; protoconch low, glossy, slightly more than 1.25 whorls; R1 of 1.75 whorls, glossy,

with widely-spaced ribs, strong only near suture and in umbilicus, represented as very fine axial lines on edge of

peristome; boundary between R1 and R2 conspicuous due to dense R2 ribs; R2 ribs curved toward aperture, ca. 28

R2 ribs present; spaces between R2 ribs narrower than ribs; R2+R3 more than quarter whorl (ca. 110˚); R2 approxi-

mately half length of R3; R3 glossy, smooth, with very fine growth lines; boundary between R2 and R3 conspicu-

ous due to change in sculpture, although constriction shallow; entire R3 with an elongated, inflated swelling remi-

niscent of an elephant seal proboscis; aperture strongly oblique to shell axis, round; boundary between inner and

outer peristomes distinct; inner peristome somewhat protruding, rather thin, outer peristome extremely expanded,

forming uniformly wide rim around aperture, slightly reflected over umbilicus, notched at the parieto-palatal edge;

umbilicus very narrow.

Measurements. D. 3.13 mm, H: 2.08 mm.

Operculum. Unknown.

Differential diagnosis. There are no other species recorded from Thailand, Myanmar, and neighbouring areas

with such an expanded outer peristome. This trait, combined with the relatively small size, elevated spire, and

smooth R1 makes this species easily recognizable.

Distribution. This new species is known only from the type locality (Fig. 17).

PÁLL-GERGELY ET AL.

FIGURE 23. Dicharax mirounga Páll-Gergely, n. sp., holotype (UF 347421).

Dicharax notus (Godwin-Austen, 1914)

Figs 24–27

Alycæus notus Godwin-Austen, 1914: 411, plate 155, fig. 12.

Alycæus (Dicharax) notus — Gude 1921: 262.

Material examined. Lectotype (hereby designated): Myanmar, Shan State, “Fort Stedman, Burma, coll. Wood-

thorpe”, NHMUK 1903.7.1.3065.1. Paralectotypes: 14 shells, same data as for lectotype, NHMUK 1903.7.1.3065.

Other Material: 1 shell (Fig. 25B), Myanmar, Mandalay State, Anesakhan, Dat Taw Gyaint Waterfall, 21°58.760’N,

96°23.116’E, 610 m a.s.l. (locality code: 2018/65), 18 Oct. 2018, A. Hunyadi leg., HNHM 104863 (D: 3.08 mm,

FIGURE 24. Dicharax notus (Godwin-Austen, 1914), A: site 2018/40 (coll. HA); B: site JG100 (coll. JG).

H: 1.76 mm); 5 shells + 4 juvenile shells, same data as preceding, HA—Shan State; 15 shells + 6 strongly eroded shells,

Myanmar, Mandalay State, Hopong, Sam Phu, Cave Ae-5 at ridge above village Ho Hwe, 20°41.103’N, 97°16.198’E (lo-

cality code: JG3), 02 Feb. 2019, J. Grego leg., JG; 21 shells + 1 juvenile shell, Myanmar, Mandalay State, Hsihseng centre E

ca. 4.5 km, left side of rd. + 1.7 km on unpaved rd., limestone rocks, 20°9.359’N, 97°17.883’E, 1140 m a.s.l. (locality code:

2018/39), 07 Oct. 2018, A. Hunyadi, K. Okubo & J.U. Otani leg., HA; 1 shell (photographed), Myanmar, Mandalay State,

Hsihseng centre E ca. 6 km, right side of rd. + 400 m on unpaved rd., limestone hill, 20°7.983’N, 97°18.145’E, 1010 m

a.s.l. (locality code: 2018/40), 07 Oct. 2018, A. Hunyadi, K. Okubo & J.U. Otani leg., HNHM 104864; 6 shells, same data

as preceding, HA; 14 shells, Myanmar, Mandalay State, Hsihseng centre E ca. 6 km, right side of rd. + 500 m on unpaved

rd., limestone hill, 20°8.002’N, 97°18.024’E, 1000 m a.s.l. (locality code: 2018/41), 07 Oct. 2018, A. Hunyadi, K. Okubo

& J.U. Otani leg., HA; 1 shell + 1 juvenile shell, Taunggyi, hill over Aye Say Tee Pagoda, Dragon Cave, 20°47.489’N,

97°3.036’E, 1380 m a.s.l. (locality code: 2018/44), 08 Oct. 2018, A. Hunyadi, K. Okubo & J.U. Otani leg., HA; 1 shell,

Myanmar, Kayah State, Demoso, Demoso spring lake (locality code: JG109), 16 May 2019, J. Grego leg., JG; 8 shells +

3 broken/eroded shells, Myanmar, Kayah State, Hpruso Distr., Maw Thi Do Village, Bo Pha Gu Cave sink, 19°21.121’N,

PÁLL-GERGELY ET AL.

97°3.759’E (locality code: JG10), 10 Feb. 2019, J. Grego leg. JG; 33 shells + 13 juvenile shells, Myanmar, Kayah State,

Demoso Distr., Han Li village, Lokalay Loku Gu Cave (Myaug a San Cave), 19°23.468’N, 97°01.372’E (locality code:

JG11), 11 Feb. 2019, J. Grego leg., JG; 1 shell, Myanmar, Kayah State, Hpruso Distr., Maw Thi Do, road towards Han

Li village, under bridge over Phruno River, 19°22.966’N, 97°02.153’E (locality code: JG100), 12 Dec. 2019, J. Grego

leg., HNHM 104865; 7 shells + 6 juvenile/broken shells, same data as preceding, JG; 26 shells + 4 juvenile/broken shells,

Myanmar, Kayah State, Hpruso Distr., Maw Thi Do, road towards Han Li Village, rocks above bridge over Phruno River,

19°23.011’N, 97°02.108’E (locality code: JG101), 12 Dec. 2019, J. Grego leg., JG; 50 shells + 17 juvenile/broken shells,

Myanmar, Kayah State, Hpruso Distr., Maw Thi Do Village, Entrance of Phruno River Cave, 19°22.744’N, 97°02.570’E

(locality code: JG102), 12 Dec. 2019, J. Grego leg., JG; 7 shells, Thailand, Chiang Rai Province, Doi Tung, 50 m before

Wat Phra That Doi Tung, around the car park, 20°19.540’N, 99°49.987’E, 1350 m a.s.l. (locality code: 2015/17), 12 Feb.

2015, A. Hunyadi leg., HA; 1 shell, Thailand, Chiang Rai Province, Doi Tung, 20°20.533’N, 99°50.350’E, 1320 m a.s.l.,

08 May 1987, F.G. Thompson leg., UF 347139.

FIGURE 25. Dicharax notus (Godwin-Austen, 1914). A: lectotype (NHMUK 1903.7.1.3065.1); B: site 2018/65 (HNHM

104863).

FIGURE 26. Dicharax notus (Godwin-Austen, 1914). A: UF 347139; B: site JG11 (operculum); C: site 2018/41 (operculum

in situ).

PÁLL-GERGELY ET AL.

FIGURE 27. Dicharax notus (Godwin-Austen, 1914). A: SEM image of the cross-section of R2; B: schematic drawing of the

same image. Abbreviations: a—anterior crust; p—posterior crust; t—microtunnel.

FIGURE 28. Distribution of Dicharax omissus (Godwin-Austen, 1914) (circles) and Dicharax notus (Godwin-Austen, 1914)

(triangles). Sample codes correspond with those in the list of examined material and Tables 2 and 3.

Diagnosis. A variable Dicharax species with glossy shell, regularly ribbed R1, widely-spaced R2 ribs, blunt to

somewhat narrow central swelling on R3, and strongly reflected outer peristome.

Description. Shell yellowish, corneous, occasionally with some reddish/pinkish colouration on initial whorls,

sometimes semi-translucent; shell outline rounded in dorsal view, spire rather low, only slightly elevated, but some-

what variable, body whorl rounded; protoconch low, glossy, 1.25–1.5 whorls; R1 approximately 1.75 whorls, sculp-

ture variable, first 1–1.25 whorl with weak growth lines or finely ribbed, gradually becoming widely-spaced, rather

prominent ribs; boundary between R1 and R2 not conspicuous but discernible because R2 ribs denser than R1;

R2 ribs curved toward aperture, ca. 20–22 R2 ribs present; R2 ribs relatively widely spaced or densely arranged;

R2+R3 ca. quarter whorl or more (90–110˚); R2 and R3 of comparable lengths, or R2 slightly shorter; R3 beginning

smooth, glossy, anterior portion (between swelling and peristome) smooth or with few ribs similar to end of R1;

boundary between R2 and R3 conspicuous due to sculptural change and rather deep constriction; middle of R3 with

prominent, variably shaped swelling, high convex or low rounded; aperture strongly oblique to shell axis, rounded;

boundary between inner and outer peristomes barely discernible, inner peristome not protruding; outer peristome

strongly thickened and reflected in all directions, even to parietal shell wall; umbilicus relatively wide, slightly less

than a third of shell width.

A cross-sectional view of R2 was examined in one specimen (Fig. 27): anterior crust forms significantly el-

evated, sometimes hollow rib, with anterior and posterior projections of comparable sizes resulting in a T-shaped

cross-section; anterior crust folds over much weaker posterior crust; posterior crust thick; cross-sectional view of

microtunnel is nearly round;

Measurements. D: 2.98–4.61 mm, H: 1.62–2.56 mm.

Operculum. The outer surface of the opercula of two live-collected specimens could be examined: it has a

closely-coiled lamina, similar to that of Dicharax species known from Vietnam (Páll-Gergely et al. 2017), although

the lamina is seemingly deciduous since only remnants were visible.

Differential diagnosis. Dicharax (?) bifrons (Theobald, 1870) (examined material: Shan States, NHMUK

1888.12.4.956–958, 3 syntypes, Fig. 20A) is rather dome-shaped, possesses two swellings on R3, and its outer peri-

stome is not much reflected. Dicharax (?) woodthorpei (Godwin-Austen, 1914) (examined material: Fort Stedman,

Burma, coll. Woodthorpe, NHMUK 1903.7.1.3064, 22 syntypes in two vials, Fig. 20B) is also somewhat similar to

this species in terms of general shell and aperture shape, but it has a higher spire, a less convex swelling on R2, and

R2 bears no elevated ribs, but has light and dark alternating colour stripes. Dicharax politus (W.T. Blanford, 1865)

(examined material: Phungdo, Arakan, coll. Blanford, NHMUK 1906.4.4.178, 3 probable syntypes, Fig. 20C) is

similar to this species in terms of general shell shape and sculpture, but differs in having a less thickened peristome,

less expanded outer peristome, denser R2 ribbing, and glossier R1. See also under Dicharax omissus.

Distribution. Dicharax notus is known from the Mandalay, Shan, and Kayah states of Myanmar, and from

Chiang Rai Province, Thailand (Fig. 28).

Remarks. This is a variable species in terms of shell size, R1 sculpture, density of R2 ribs, and the narrow width

of the R3 swelling. See Table 2.

The Japanese Metalycaeus vinctus (Pilsbry, 1902) and M. minatoi Páll-Gergely, 2017 are probably sister spe-

cies to each other with ribbed and smooth R2s, respectively (Páll-Gergely & Asami 2017). Dicharax notus and D.

woodthorpei may present a similar situation, because they are very similar in shell shape and have geographically

adjacent distributions, differing mostly in the fine morphology of the R2 ribs, indicating that the character may be

the subject of rapid evolutionary changes.

TABLE 2. Variation of shell characters of Dicharax notus (Godwin-Austen, 1914).

shell diameter

(in mm) R1 sculpture R2 ribs R3 swelling

typical notus beginning - smooth; end - ribs strong,

moderately widely spaced

intercostal spaces

narrower than ribs blunt

2018/65 2.89–3.09

beginning - smooth; end - ribs strong,

widely spaced

intercostal spaces

as wide as ribs blunt

Ho Hwe village (JG3) 3.16–3.66

beginning - finely, densely ribbed; end

- ribs strong, widely spaced

intercostal spaces

as wide as ribs blunt

east of Hsihseng

centre (2018/39,

2018/40, 2018/41) 4.41–4.61

beginning - finely, densely ribbed; end

- ribs strong, widely or very widely

spaced

intercostal spaces

as wide as ribs

elevated in

most shells

Maw Thi Do Village

(JG10, JG11, JG100,

JG101, JG102) 3.81–4.01

beginning - finely, densely ribbed; end

- ribs moderately strong, moderately

widely to widely spaced

intercostal spaces

narrower than ribs

rounded to

somewhat

elevated

Demoso (JG109) beginning - finely, densely ribbed; end

- ribs strong, widely spaced

intercostal spaces

as wide as ribs blunt

Doi Thung (UF

347139, 2015/17)

4.1

entire R1 with strong, widely-spaced

ribs

intercostal spaces

almost non-

existent, ribs

almost in contact elevated

PÁLL-GERGELY ET AL.

Dicharax omissus (Godwin-Austen, 1914)

Figs 29–30

Alycæus omissus Godwin-Austen, 1914: 411, Plate 155, Fig. 13.

Alycæus (Chamalycaeus) omissus — Gude 1921: 231.

Material examined. Lectotype (hereby designated): 1 shell, “Siam & Shan boundary, coll. Woodthorpe”, NHMUK

1903.7.1.1228.1. Paralectotype: 1 shell, same data as for lectotype, NHMUK 1903.7.1.1228. Other material: 1

shell (Fig. 29B, D: 2.94 mm, H: 1.94 mm) + 10 shells, Myanmar, Shan State, Hopong centre 5.8 km—Namsang,

left side of rd. #4, near „Hopong Spring Cave”, 20°49.028’N, 97°13.469’E, 1110 m a.s.l. (locality code: 2018/35),

06 Oct. 2018, A. Hunyadi, K. Okubo & J.U. Otani leg., HA; 8 shells, Myanmar, Shan State, Taunggyi centre ca. 16

km—Hopong, rd. #4 N 1.5 km, „Shwe Pyi Aunchonda” monastery, 20°47.263’N, 97°8.239’E, 1110 m a.s.l. (locality

code: 2018/46), 08 Oct. 2018, A. Hunyadi, K. Okubo & J.U. Otani leg., HA; 1 shell (Fig. 30A, D: 2.81 mm, H: 1.8

mm) + 7 shells, Thailand, Chiang Mai Province, 1.2 km N of Wat Tham Klaeb, 500 m side road from the junction,

19°33.918’N, 99°3.690’E, 650 m a.s.l. (locality code: 2015/08), 08 Feb. 2015, A. Hunyadi leg., HA; 1 shell (Fig.

30B, D: 2.69 mm, H: 1.75 mm) + 2 shells, Thailand, Mae Hong Son Province, 800 m from Tham Nam Lod toward

the Buddhist temple, 19°33.928’N, 98°16.794’E, 650 m a.s.l. (locality code: 2015/12), 09 Feb. 2015, A. Hunyadi

leg., HA.

FIGURE 29. Dicharax omissus (Godwin-Austen, 1914). A: lectotype (NHMUK 1903.7.1.1228.1); B: site 2018/35.

FIGURE 30. Dicharax omissus (Godwin-Austen, 1914). A: site 2015/08 (coll. HA); B: site 2015/12 (coll. HA).

Type locality. “Siam and Shan boundary”.

Diagnosis. A variable Dicharax species with a relatively densely, regularly ribbed R1, rarely with spiral stria-

tion, dense R2 ribs, a rounded central swelling on R3, and an expanded, but not reflected outer peristome.

Measurements. D: 2.52–2.87 mm, H: 1.71–1.89 mm (2018/08 and 2015/12); D: 2.89–3.23 mm, H: 1.88–2.3

mm (2018/35 and 2015/46).

Differential diagnosis. Typical Dicharax notus and D. omissus are very similar, and since only eroded speci-

mens of the latter species were available, the distinction of these two species was somewhat questionable until

newly collected material became available. These specimens reveal that D. notus is generally larger, R1 bears denser

ribs (although some populations of D. notus have less dense R2 ribs), and its outer peristome is more reflected.

Distribution. Dicharax omissus is known from the Shan States of Myanmar and neighbouring Thai provinces

of Chiang Mai and Mae Hong Son (Jirapatrasilp et al. 2021; Fig. 28).

Remarks. The syntypes and the newly collected 4 samples (possibly 3 populations) show some variability in

terms of the sculpture of R1 and R3, and the presence or absence of the notch at the basal portion of the aperture.

However, all of these traits are rather minor and do not justify the distinction of species. The conchological differ-

ences of these populations are summarized in Table 3.

PÁLL-GERGELY ET AL.

TABLE 3. Variation of shell characters of Dicharax omissus (Godwin-Austen, 1914).

shell diameter (in mm) R1 sculpture R3 sculpture aperture

typical omissus ? without spiral striation smooth without basal notch

2015/08 2.61–2.87 without spiral striation smooth with basal notch

2015/12 2.52–2.84 without spiral striation finely ribbed with basal notch

2015/35, 2015/46 2.89–3.23 with spiral striation finely ribbed without basal notch

The shells of the two samples from Hopong have some slight spiral striation on the R1, which is highly unusual

in Dicharax. The spiral striae of this species might not be homologous with those of other alycaeid genera, although

this requires further investigation.

FIGURE 31. Shells of Dicharax Kobelt & Möllendorff, 1900 species. A: Dicharax ovatus Páll-Gergely & Auffenberg, n. sp.,

holotype (UF 345330); B: Dicharax parvulus (Möllendorff, 1887), lectotype (SMF 109507).

Dicharax ovatus Páll-Gergely & Auffenberg n. sp.

Fig. 31A

Material examined. Holotype: Thailand, Surat Thani Province, Highway 401, 2.7 km W junction Highway 4142

and 401, evergreen forest on rocky hillside, 9°10’N, 99°40’E, 90 m a.s.l., 19 April 1988, K. Auffenberg leg., below

cliff, base of cliff, UF 345330 (D: 1.86 mm, H: 0.99 mm). Paratypes: 5 shells, same data as holotype, UF 551223.

Other Material: 3 broken shells, same data as holotype, UF 551224.

Etymology. Named for the ovate (Latin derivation: ovatus) shell shape (in dorsal view).

Diagnosis. A tiny Dicharax species with depressed shell, finely ribbed R1, R2+R3 less than a quarter whorl, R2

with slightly curved ribs shorter than R2.

Description. Shell off-white, light yellowish; shell outline oval in dorsal view, spire depressed, nearly flat;

body whorl rounded; protoconch low, rather glossy, 1.25–1.5 whorls; R1 of 1.25 whorls; R1 with fine, regular, dense

ribs, gradually become more widely-spaced and elevated toward R1 termination; boundary between R1 and R2 not

conspicuous but discernible due to denser R2 ribs than those of R1; R2 with low ribs that slightly curve toward

aperture, ca. 24–26 R2 ribs present; R2+R3 less than quarter whorl (ca. 80˚); R2 slightly shorter than R3; R3 with

low ribs of similar density to those on R1; boundary between R2 and R3 clear due to change in rib density and shal-

low constriction; very low swelling on R3 only indicated; aperture slightly oblique to shell axis, rounded; boundary

between inner and outer peristomes distinct; inner peristome thin, slightly protruding and expanded, rather narrow,

outer peristome thicker than inner peristome, strongly expanded but not reflected; umbilicus wide, sigmoid, more

than a third of shell width.

Measurements. D: 1.81–1.95 mm, H: 0.93–1.1 mm.

Operculum. unknown.

Differential diagnosis. The most similar species regarding size and the dense, fine ribbing is the nearby occur-

ring Chamalycaeus canaliculatus (examined material: Golf von Siam: Koh-Samui, coll. Möllendorff, SMF 109468,

lectotype), which has a more pronounced constriction at border of R2 and R3, and a narrower swelling on R3.

Chamalycaeus armillatus (Benson, 1856) has a more elevated spire, the first 1–1.5 whorls of the teleoconch are

smooth and glossy, and the last whorl of R1 has spiral striation. Dicharax parvulus (Möllendorff, 1887) (examined

material: Malakka: Bukit Pondong (Perak), coll. Möllendorff, SMF 109507, lectotype, Fig. 31B) is smaller, has a

comparatively larger aperture, a more thickened peristome, and a shorter R2.

Distribution. This new species is known only from the type locality (Fig. 3).

Dicharax stuparum Páll-Gergely & Hunyadi, 2018

Fig. 32

Dicharax stuparum Páll-Gergely & Hunyadi, 2018: 62, figs 1F–K.

New material examined. 7 shells, Thailand, Chiang Rai Province, Doi Thung; 20°20.533’N, 99°50.350’E, 1320 m

a.s.l., 08 May 1988, F.G. Thompson leg., UF 347150.

Type locality. Thailand, Chiang Rai Province, Doi Tung, 50 m before Wat Phra That Doi Tung, around the car

park, 20°19.540’N, 99°49.987’E, 1350 m a.s.l.

Operculum. The operculum was not described in the original description, but a live-collected specimen from

the Florida Museum allows description. The operculum is extremely thin, translucent, concave; outer surface glossy,

without any notable structures, inner surface with a low but pointed, central nipple.

Remarks. The newly examined specimens were collected very near the type locality of D. stuparum (Fig.

17).

Dicharax subroseus Páll-Gergely n. sp.

Fig. 33

Material examined. Holotype: Thailand, Surat Thani Province, limestone hill right side off km. 105.2 rd. #401

PÁLL-GERGELY ET AL.

(Suratthani—Takuapa), 8°53.622’N, 98°33.179’E (locality code: Th.119.00), Ch. & J. Hemmen leg., SMF 360000

(D: 2.79 mm, H: 1.83 mm). Paratype: 1 shell, same data as holotype, SMF 360001.

FIGURE 32. Dicharax stuparum Páll-Gergely & Hunyadi, 2018, UF 347150.

Etymology. The specific epithet refers to the slight pinkish coloration of the available specimens.

Diagnosis. A Dicharax species with a depressed shell, slight pinkish colouration, very widely spaced ribs on the

last whorl of R1, a short R2 with straight, widely-spaced ribs, and a comparatively small, rounded aperture.

Description. Shell whitish-yellowish with some pinkish colouration (holotype at the R2-R3 area, paratype on

initial whorls); shell outline rounded in dorsal view; spire only slightly elevated; body whorl rounded; protoconch

low, rather glossy, 1.25–1.5 whorls; R1 of 1.75–2 whorls; first whorl of R1 with only weak growth lines, gradually

changing to strongly ribbed, spaces between ribs increase width rapidly (last half whorl of R1 with only 15–20

ribs); ribs straight, strong, narrow, but relatively low; boundary between R1 and R2 distinct due to denser R2 ribs;

R2 with ca. 16, widely-spaced, low and rather narrow; R2+R3 approximately a quarter whorl or slightly more; R2

slightly shorter than R3; boundary between R2 and R3 conspicuous due to smooth R3 beginning and rather deep

constriction; R3 with widely-spaced ribs, only anterior to constriction similar to those on R1, and blunt but promi-

nent central swelling; aperture strongly oblique to shell axis, rounded, conspicuously small compared to shell size;

boundary between inner and outer peristomes distinct; inner peristome prominent, protruding, relatively narrow;

outer peristome as strong as inner peristome, strongly expanded, slightly reflected; umbilicus wide, approximately

a third of shell width.

Measurements. D: 2.74–2.79 mm, H: 1.7–1.83 mm.

Operculum. The holotype possesses an operculum in the original position which appears to be separated into

two layers. The outer layer, being partly broken, allows examination of the more deeply set layer. The outer surface

is glossy without any surface structures. A central nipple is visible through the semi-translucent inner layer.

Differential diagnosis. The combination of small size, widely-spaced R1 ribs, and a relatively small aperture

is unlike any other species in the region.

Distribution. This new species is known only from the type locality (Fig. 3).

FIGURE 33. Dicharax subroseus Páll-Gergely, n. sp., A: holotype (SMF 360000); B: Holotype, operculum in situ; C: paratype

(SMF 360001).

PÁLL-GERGELY ET AL.

Dicharax verrucosus Páll-Gergely & Hunyadi n. sp.

Fig. 34

Material examined. Holotype: Myanmar, Shan State, Taunggyi, hill above Aye Say Tee Pagoda, Dragon Cave,

20°47.489’N, 97°03.036’E, 1380 m a.s.l. (locality code: 2018/44), 08 Oct. 2018, A. Hunyadi, K. Okubo & J.U.

Otani leg., HNHM 104862 (holotype: D: 2.83 mm, H: 2.14 mm). Paratypes: 10 shells, same data as holotype, HA.

Other material: 2 shells, Myanmar, Shan State, Hsihseng centre E ca. 6 km, right side of rd. + 400 m on unpaved

rd., limestone hill, 20°7.983’N, 97°18.145’E, 1010 m a.s.l. (locality code: 2018/40), 07 Oct. 2018, A. Hunyadi, K.

Okubo & J.U. Otani leg., HA.

FIGURE 34. Dicharax verrucosus Páll-Gergely & Hunyadi n. sp., A: holotype (HNHM 104862), B: specimen from sample

2018/40 (coll. HA).

Etymology. The specific epithet verrucosus (Latin for excrescence/wart) refers to the small swelling on R3,

reminiscent of a wart.

Diagnosis. A Dicharax species with a relatively high spire, glossy, smooth R1, R2+R3 about a quarter whorl

(R3 shorter than R2), and blunt swelling on R3.

Description. Shell light grey, possibly translucent when fresh; shell outline rounded in dorsal view, spire elevat-

ed, body whorl rounded; protoconch low, rather glossy, 1.5 whorls; R1 approximately 2.25 whorls, smooth, glossy,

with occasional, weak growth lines; boundary between R1 and R2 conspicuous due to dense R2 ribs; R2 ribs curved

toward aperture, ca. 36–38 R2 ribs present; R2 ribs situated close to each other, spaces between ribs much less than

rib width; R2+R3 covers ca. quarter whorl; R3 very short; about half as long as R2; sculpture of R3 similar to R1,

boundary between R2 and R3 distinct, indicated by deep constriction; middle of R3 with prominent, blunt swelling;

aperture slightly oblique to shell axis; rounded, with slight upper incision in parieto-palatal region; boundary be-

tween inner and outer peristomes distinct, especially at columellar portion; inner peristome slim, slightly protruding,

outer peristome strongly thickened, expanded and reflected, especially toward umbilicus (in sample 2018/40 more

conspicuously than in 2018/44); umbilicus relatively narrow, less than a third of shell width.

Measurements. D: 2.76–3.24 mm, H: 2.1–2.46 mm (2018/44); D: 3.21–3.55 mm, H: 2.46–2.5 mm (2018/40).

Operculum. Unknown.

Differential diagnosis. The combination of the elevated spire, smooth R2, short R3 with a prominent swelling

distinguishes this species from all congeners.

Distribution. Both known populations occur in the southeastern part of Shan States, Myanmar. The straight-

line distance between the two is ca. 77 km (Fig. 17).

Remarks. The typical shells from Taunggyi are slightly smaller, and have less reflected peristomes than speci-

mens from Hsihseng. However, since all other shell characters (shape, ratios of the shell regions, and shell sculp-

ture) are identical, we treat them as the same species.

Genus Metalycaeus Pilsbry, 1900

Alycaeus (Metalycæus) Pilsbry, 1900: 382.

Type species. Alycaeus (Metalycaeus) melanopoma Pilsbry, 1900 (synonym of Alycaeus nipponensis Reinhardt,

1877, see Minato 1988), by subsequent designation (Thiele 1929).

Diagnosis. Metalycaeus is characterized by the presence of spiral striation on both the protoconch and teleo-

conch (Páll-Gergely et al. 2017, 2020). However, some shells of one Japanese species lacks spiral striation on the

protoconch. Here we report a species (M. pygmachos n. sp.) lacking spiral striation on the entire shell, but based on

other characters, is best assigned to this genus. Thus, examination of shell characters other than the spirally striated

protoconch is also necessary.

Metalycaeus anas Páll-Gergely & A. Reischütz n. sp.

Figs 35–36

Material examined. Holotype: Thailand, Chiang Rai Province, Wat Phra That Tham Doi Khong Khao Meditation

Centre, ca. 8 km W of Chiang Rai, cave clay at entrance of cave, 19°54.771’N, 99°46.607’E, ca. 420 m a.s.l. (local-

ity code: Th6), Sep. 2007, A. Reischütz leg., NHMW 113489 (D: 3.3 mm, H: 2.05 mm). Paratypes: 1 shell (fig.

35B), same data as holotype, NHMW 113490; 7 shells, same data as holotype, RE; 2 shells, same data as holotype,

CUMZ 5270. Other Material: 4 broken shells, same data as holotype, RE.

Etymology. The specific epithet (noun in apposition) derives from the shape of R3 that resembles a duck’s beak

(anas = duck in Latin).

Diagnosis. A medium-sized Metalycaeus species with a weakly sculptured R1 (fine growth lines and spiral

striae), almost smooth R2, a R3 with convex, central swelling and a rounded aperture.

Description. Shell light grey, probably somewhat translucent when fresh; shell outline slightly oval in dorsal

view, spire somewhat elevated, low conical; body whorl rounded (rather “parabolic”); protoconch conspicuously

PÁLL-GERGELY ET AL.

FIGURE 35. Metalycaeus anas Páll-Gergely & A. Reischütz n. sp., A: holotype (NHMW 113489); B: paratype (NHMW

113490).

large to shell size, somewhat elevated, last whorl spirally striated, 1.5 whorls; R1 of 1.25 whorls, with very weak ribs

(growth lines) occasionally moderately strong near suture, and fine spiral striations; boundary between R1 and R2

distinct due to R2 axial sculpture; R2 with narrow, somewhat elevated light-coloured stripes alternating with broader,

darker stripes, ca. 24–32 R2 stripes present; R2+R3 approximately or slightly more than quarter whorl; R2 slightly

shorter than R3; R3 practically smooth, bearing only low growth lines; boundary between R2 and R3 distinct due to

lack of R3 light stripes (ribs) and rather deep constriction; R3 with elevated, convex central swelling with anterior

slope steeper than posterior; aperture strongly oblique to shell axis; round; boundary between inner and outer peri-

stomes distinct; inner peristome protruding, expanded, rather slim; outer peristome of comparable strength, expanded,

and slightly reflected toward umbilicus; umbilicus relatively narrow, approximately one fourth the shell width.

FIGURE 36. Shell sculpture of Metalycaeus anas Páll-Gergely & A. Reischütz n. sp., A–D: holotype (NHMW 113489); E–G:

cross-sectional view of R2 (paratype from the type locality, RE). Abbreviations: a—anterior crust; p—posterior crust; t—mi-

crotunnel.

PÁLL-GERGELY ET AL.

FIGURE 37. Metalycaeus rubinus (Godwin-Austen, 1893), syntype (NHMUK 1903.7.1.2685).

A cross-sectional view of R2 of one specimen was examined (Fig. 36E–G): anterior crust very slightly elevated,

forming very low, blunt rib; anterior crust and the slightly weaker posterior crust adnate, forming slender microtun-

nel in cross-sectional view.

Measurements. D: 3.3–3.91 mm, H: 2.05–2.26 mm.

Operculum. unknown.

Differential diagnosis. Metalycaeus rubinus (Godwin-Austen, 1893) (examined material: Ruby Mines District,

Up. Burma, leg. Doherty, NHMUK 1903.7.1.2685, 2 syntypes, Fig. 37) is the only Metalycaeus species reported

from Myanmar having atypical R2 ribbing. It is far larger and has an elevated spire.

Distribution. This new species is known only from the type locality (Fig. 17).

Metalycaeus aries Páll-Gergely & Auffenberg, n. sp.

Figs 38, 39A, 40A–D

Material examined. Holotype: Thailand, Loei Province, limestone knoll 1 km E Ban Huai Muang, top of knoll,

17°28.433’N, 101°53.333’E, 375 m a.s.l., 21 May 1987, F.G. Thompson leg., in leaf litter, UF 343786 (D: 2.48 mm,

H: 1.49 mm). Paratypes: 12 shells, same data as holotype, UF 551225. Other material: 1 shell (Fig. 38B, D: 2.2

mm, H: 1.61 mm) + 5 shells + 4 juvenile shells, Thailand, Nakhon Sawan Province, limestone hill 4.0 km NW of

Man Non San, 15°56.517’N, 99°52.400’E, 100 m a.s.l., 12 Jun. 1987, F.G. Thompson leg., UF 279699; 1 shell (Fig.

38C, D: 2.04 mm, H: 1.25 mm) + 3 shells, Thailand, Phetchabun Province, 24.4 km S Phetchabun on Highway 2275

evergreen forest in back of outcrop, base of cliff, 16°16’N, 101°10’E, 120 m a.s.l., 02 May 1988, K. Auffenberg

leg., UF 346105.

FIGURE 38. Metalycaeus aries Páll-Gergely & Auffenberg, n. sp., A: UF 279699; B: operculum (UF 279699, other specimen

than FIG. A); C: UF 346105.

PÁLL-GERGELY ET AL.

FIGURE 39. Shells of Metalycaeus Pilsbry, 1900 species. A: Metalycaeus aries Páll-Gergely & Auffenberg, n. sp., holotype

(UF 343786); B: Metalycaeus bicarinatus Páll-Gergely & Hunyadi, n. sp., holotype (HNHM 104868).

FIGURE 40. A–D: Metalycaeus aries Páll-Gergely & Auffenberg, n. sp., holotype (UF 343786); E–H: Metalycaeus bicarinatus

Páll-Gergely & Hunyadi, n. sp., holotype (HNHM 104868).

PÁLL-GERGELY ET AL.

Etymology. The shape of the shell of this new species is reminiscent of a coiled ram’s horn (aries in Latin). The

specific epithet is used as a noun in apposition.

Diagnosis. A tiny Metalycaeus species with strongly ribbed R1, short combined R2+R3, dense, curved R2 ribs,

and an angled R2 visible from dorsal side.

Description of the type series. Shell off-white, light grey, although all available shells dead collected; shell

outline slightly oval in dorsal view, R2 conspicuously swollen/angled; spire somewhat elevated, low conical; body

whorl rounded with distinct lower, keel caused by angled ribs; protoconch of 1.5 whorls, elevated, first ca. 0.75

whorl finely granular and glossy, the last 0.75 whorl spirally striated; R1 of 1.5–1.75 whorls, with strong, equidistant,

narrow ribs and fine, dense spiral striae between ribs; boundary between R1 and R2 distinct due to densely-placed

R2 ribs; R2+R3 less than a quarter whorl (ca. 70˚); R2 swollen, forming blunt angle in dorsal view, and rounded in

apertural view; R2 ribs curved toward aperture, nearly adnate, ca. 24–26 R2 ribs present; R2 and R3 of comparable

length; R3 with spiral striation and weaker ribs than R1; boundary between R2 and R3 distinct due to lower R3

ribs and descending portion of R2 angle; aperture slightly oblique to shell axis, round; boundary between inner and

outer peristomes distinct; inner peristome protruding and expanded, relatively thin; outer peristome thicker, wider,

expanded, and very slightly reflected toward umbilicus; umbilicus moderately narrow, approximately one third of

shell width.

Measurements. 2.04–2.54 mm, H: 1.3–1.61 mm.

Operculum. An operculum was present in one specimen (UF 279699). Outer surface multispiral without el-

evated lamina, originally covered with mud (a portion left on operculum for photography; Fig. 38B), inner surface

with very small, low, central nipple.

Differential diagnosis. The only similar species is M. bicarinatus n. sp., which has two distinct keels in R2, has

slimmer, more elevated, and more widely-spaced ribs, and the protoconch lacks obvious spiral striae.

Distribution. Three populations are known from the Thai provinces of Loei, Nakhon Sawan, and Phetchabun

(Fig. 5).

Remarks. The three populations classified as M. aries n. sp. show some conchological variability, which is

compiled in Table 4.

TABLE 4. Variation of shell characters of Metalycaeus aries Páll-Gergely & Auffenberg, n. sp.

shell diameter spire R2 R1 spiral striation

UF 343786 2.21–2.54 lower more angled stronger thicker

UF 279699 2.15–2.21 higher more angled weaker thicker

UF 346105 2.04–2.11 lower less angled weaker thinner

Metalycaeus bicarinatus Páll-Gergely & Hunyadi n. sp.

Figs 39B, 40E–H

Material examined. Holotype: Thailand, Phetchaburi Province, Khao Yoi, NE side of the hill, 13°14.316’N,

99°49.493’E, 30 m a.s.l. (locality code: 2015/39), 24 Feb. 2015, A. Hunyadi leg. HNHM 104868 (D: 2.33 mm, H:

1.63 mm). Paratype: 1 shell, same data as holotype, HA. Other Material: 4 juvenile/broken shells; same data as

holotype, HA.

Etymology. This new species is named after the most remarkable conchological character, the double keel of

R2.

Diagnosis. A tiny Metalycaeus species with a strongly ribbed R1, ribs narrow and elevated, short R2+R3,

dense, curved R2 ribs, and an R2 with double keel, visible from lateral and ventral sides.

Differential diagnosis. Due to the peculiarly carinated R2 no other alycaeid species is similar, except for M.

aries n. sp. (see above).

Description of the type series. Shell off-white, light grey, although available shells were dead collected; shell

rounded in dorsal view; spire elevated, low conical; R1 body whorl rounded, R2 has distinct upper and lower keels

separated by flattened zone, resulting in rectangular-shaped R2; protoconch consisting of 1.25 whorls, elevated,

finely granular, last ca. quarter whorl with granules arranged into oblique striae; R1 of 1.75 whorls, with strong,

narrow, elevated, equidistant ribs, areas between ribs with fine, dense spiral striae; boundary between R1 and R2

distinct because of denser R2 ribs; R2+R3 less than a quarter whorl (ca. 80˚); R2 very slightly swollen in dorsal

view, and rectangular in lateral view due to upper and lower keels; R2 ribs curved toward aperture, nearly adnate, ca.

26 R2 ribs present; R2 somewhat longer than R3; R3 strongly reduced, with remnants of spiral striation and rough

growth lines; R2 and R3 boundary distinct due to change in rib morphology and moderate constriction; aperture

slightly oblique to shell axis; round; boundary between inner and outer peristomes barely discernible; inner peri-

stome slightly protruding and expanded, relatively thin; outer peristome also thin, slightly expanded, not reflected;

umbilicus moderately narrow, approximately one third of shell width.

Measurements. D: 2.33–2.4 mm, H: 1.63–1.87 mm.

Operculum. Unknown.

Distribution. This new species is known only from the type locality (Fig. 5).

Remarks. This species is assigned to Metalycaeus even though no spiral striation has been found on the pro-

toconch. Since all available material was dead collected, we believe that the fine shell sculpture that exists between

the ribs at the end of the protoconch is probably remnants of spiral striation. Also, the protoconch of Metalycaeus

aries n. sp., the conchologically most similar species is clearly spirally striated (see above).

Metalycaeus heudei (Bavay & Dautzenberg, 1900)

Fig. 41

Alycaeus (Charax) heudei Bavay & Dautzenberg, 1900a: 121–122.

Alycaeus (Charax) heudei — Bavay & Dautzenberg 1900b: 458–459, plate 11, figs 15–18.

Alycaeus paviei Bavay & Dautzenberg, 1912: 50–51, pl. 4, figs 5–8.

Alycaeus paviei var. minor Bavay & Dautzenberg, 1912: 51, pl. 4, fig. 9.

Chamalycaeus (Dicharax) compressicosta Zilch, 1957: 145–146, fig. 33.

Chamalycaeus (Dicharax) fractus Varga, 1974: 165–167, figs 1–5.

Alycaeus zhuangiyucuii Yang, Fan, Qiao & He, 2012: 32, fig. 2.

Metalycaeus heudei — Páll-Gergely et al. 2017: 74–84, figs 49C–D, 50–52, 53C–D. (paviei Bavay & Dautzenberg, 1912, paviei

var. minor Bavay & Dautzenberg, 1912, compressicosta Zilch, 1957, fractus Varga, 1974 and zhuangiyucuii Yang, Fan,

Qiao & He, 2012 are synonyms; Inkhavilay et al. 2019: 16, fig. 6C.

Alycæus kengtungensis Godwin-Austen, 1914: 409, plate 139, figs 6, 6a. new synonym

Material examined. Holotype: Myanmar, Shan State, “Kengtung, Siam Frontier, leg. Woodthorpe”, NHMUK

1903.7.1.3037 (holotype of A. kengtungensis). For the examined type specimens of other taxa see Páll-Gergely et

al. (2017). Other material: 4 shells, Myanmar, Kayah State, Hpruso Distr., Maw Thi Do Village, Bo Pha Gu Cave

sink, 19°21.121’N, 97°3.759’E (locality code: JG10), 10 Feb. 2019, J. Grego leg., JG; 2 shells, Myanmar, Kayah

State, Hpruso Distr., Maw Thi Do, road towards Han Li Village, under bridge over Phruno River, 19°22.966’N,

97°02.153’E (locality code: JG100), 12 Dec. 2019, J. Grego leg., JG; 1 shell, Myanmar, Kayah State, Hpruso Distr.,

Maw Thi Do, road towards Han Li Village, rocks above bridge over Phruno River, 19°23.011’N, 97°02.108’E (lo-

cality code: JG101), 12 Dec. 2019, J. Grego leg., JG; 1 shell, Myanmar, Kayah State, Hpruso Distr., Maw Thi Do

Village, Entrance of Phruno River Cave, 19°22.744’N, 97°02.570’E (locality code: JG102), 12 Dec. 2019, J. Grego

leg., HNHM 104867 (photographed shell: 4.77 mm, H: 3.66 mm); 17 shells, same data as preceding, JG.

Diagnosis of specimens from Myanmar. A medium-sized to large species with very long R2 having typical

Metalycaeus-type elevated, thin, widely spaced ribs, a narrow swelling on R3, and a rounded aperture.

Measurements. D: 4.65–5.05 mm, H: 3.66–3.71 mm (newly collected specimens).

Remarks. Metalycaeus heudei is a widely distributed, variable species reported from China, Vietnam and Laos.

Alycaeus kengtungensis (Fig. 41B) from the eastern border of Shan State, Myanmar, and the newly collected shells

from Kayah State (Fig. 5) fall within the known morphological variation of Metalycaeus heudei . Therefore, we

consider A. kengtungensis a new synonym of M. heudei. With this, M. heudei is the most widely distributed alycaeid

species known.

PÁLL-GERGELY ET AL.

FIGURE 41. Metalycaeus heudei (Bavay & Dautzenberg, 1900). A: from Kayah State, Myanmar (site JG102); B: holotype of

Alycaeus kengtungensis Godwin-Austen, 1914 (NHMUK 1903.7.1.3037).

Metalycaeus pygmachos Páll-Gergely & Hunyadi n. sp.

Fig. 42

Material examined. Holotype: Myanmar, Mandalay State, near Maha Nandamu Peik Chin Myaung Cave & Wa-

terfall, 22°05.762’N, 96°37.087’E, 740 m a.s.l. (locality code: 2018/66), 19 Oct. 2018, A. Hunyadi leg., HNHM

104866 (D: 4.8 mm, H: 2.91 mm). Paratype: 1 shell, same data as holotype, HA.

Etymology. The specific epithet pygmachos (πυγμαχος: Greek for boxer) refers to the peculiarly shaped R3

resembling a boxer’s face after being punched.

Diagnosis. A large Metalycaeus species with a long, swollen R2 having widely-spaced slim ribs, and a com-

plex, conspicuous swelling on R3.

FIGURE 42. Metalycaeus pygmachos Páll-Gergely & Hunyadi, n. sp., holotype (HNHM 104866).

PÁLL-GERGELY ET AL.

Description. Shell off-white, although both available shells are eroded; shell outline oval in dorsal view due

to conspicuously swollen R2; spire slightly elevated, domed; body whorl rounded; protoconch low, finely granu-

lar, spiral striae lacking, 1.25 whorls; R1 of 1.75–2 whorls, with strong, elevated, equidistant ribs and some faint,

dense spiral striation; boundary between R1 and R2 not conspicuous because R1 and R2 ribs identical in shape and

density; R2 with ca. 30–32 R2 ribs; R2+R3 almost half whorl (ca. 150–160˚); R2 slightly longer than R3; boundary

between R2 and R3 indicated with very deep constriction; R3 characterized by very complex swelling strongly de-

pressed dorsolaterally; this elongate depression parallel to constriction, corresponds with irregularly swollen ridge

visible in oblique view in aperture; depression results in a U-shaped R3 swelling; upper rim of U, visible in dorsal

view, more swollen than narrower lower rim, visible in lateral view; additional small depression just anterior to

upper swollen rim, i.e. between upper, swollen rim and peristome, corresponding to a separate, knob-like swelling

inside aperture; aperture strongly oblique to shell axis, rounded with slight upper and lower incisions; boundary

between inner and outer peristomes barely discernible, inner peristome slightly protruding and expanded, outer

peristome much stronger, wider, expanded, and reflected toward umbilicus, wide distance between inner peristome

and edge of outer peristome resulting in strongly thickened lip; umbilicus relatively narrow, approximately less than

one third of shell width.

Measurements. 4.8–5.1 mm, H: 2.91–2.98 mm.

Operculum. Unknown.

Differential diagnosis. The peculiarly shaped R3 swelling is a unique feature distinguishing this species from

all Chamalycaeus and Metalycaeus species.

Distribution. This new species is known only from the type locality (Fig. 5).

Remarks. This species is classified in the genus Metalycaeus due to its large size and the “depressed swell-

ing” on R3 as in other Metalycaeus species. The lack of spiral striation on the protoconch is considered a secondary

reduction.

Concluding remarks

Nineteen new species are described here (Fig. 43) collected by a few field biologists at a few isolated localities in

Myanmar and Thailand, suggesting that still many undescribed species await discovery in Southeast Asia’s lime-

stone outcrops.

Biogeography

In addition to the description of the new species and new data on the morphology and distribution of a few known

species, this paper presents the following conclusions:

- The Metalycaeus species described here represent the first records of that genus in Thailand, and the southernmost

localities for Metalycaeus (Fig. 44; Páll-Gergely et al. 2020).

- The numerous Chamalycaeus species recorded from southern Thailand indicate a diversity centre for the genus.

- The numerous Dicharax species from northern Thailand clearly show that this genus retains high diversity con-

tinuously from the southeastern Himalaya east into northern Thailand. In contrast, the genus is much less diverse in

neighbouring northern Laos (Fig. 44).

- The distribution of Metalycaeus heudei ranges from Kayah Province, Myanmar east and north to Hubei Province,

China, covering a distance of more than 1800 km. Metalycaeus heudei has the largest distributional area of all aly-

caeids and one of the largest among all terrestrial caenogastropods.

- For Dicharax diminutus (Heude, 1885) and D. dolichodeiros (Heude, 1890), populations were found several

hundred kilometres apart from each other without material from intervening areas (see Páll-Gergely et al. 2017). A

similar situation for Chamalycaeus irmatallus n. sp. is reported here. Four hypotheses were outlined by Páll-Gergely

et al. (2017) to explain the previously reported distributional gaps: 1) the gaps between known populations are due

to poor collecting effort and the lack of material; 2) those species may have once had wider distributions that have

become restricted into smaller, relict populations; 3) long distance dispersal events; or 4) convergent evolution of

shell characters resulting in misidentifications and thus, incorrect distributions. Additional material and genetic/ana-

tomical data will hopefully clarify our understanding of these species.

FIGURE 43. Synoptic view of all new species introduced herein. White lines separate genera.

PÁLL-GERGELY ET AL.

FIGURE 44. Distribution of the genera Chamalycaeus (dark grey) and Metalycaeus (light grey) (modified with new data from

Páll-Gergely et al. 2020).

FIGURE 45. Sign of predation on a Dicharax notus (Godwin-Austen, 1914) shell (site JG11).

Predation

Some shells we examined had scraped predation holes (Fig. 45), possibly caused by Atopos Simroth, 1891 slugs (see

Liew & Schilthuizen 2014; M. Schilthuizen, pers. comm.). Samples of Dicharax notus were large enough to provide

meaningful information (see Table 5). This indicates that the predation pressure is highly variable between sites (0%

for JG10, 4% in JG102 and 42% in JG11); in some cases almost half of the shells show signs of predation.

TABLE 5. Intact and scraped shells of Dicharax notus (Godwin-Austen, 1914).

sample code intact shells shells with scraped holes broken, reason unknown

JG11 19 14

JG101 18 6 2

JG100 4 3

JG10 8 0

JG102 48 2

Acknowledgements

We are very grateful to Jonathan Ablett (NHM), Sheikh Sajan (ZSI), Chirasak Sutcharit and Sigrid Hof and Ronald

Janssen (SMF) for providing access to the museum specimens under their care and providing photos of specimens;

to John Slapcinsky (UF) for the loan of museum specimens for examination; to Jaap J. Vermeulen and Thomas

A. Neubauer for reviewing, and to Alexander Nützel and Mathias Harzhauser for editing the manuscript. Christa

Hemmen, Kanji Okubo and Simon Aiken provided additional specimens. Harry G. Lee and Ed Cavin, Jacksonville,

Florida, assisted KA during fieldwork in Kanchanaburi Province, Thailand and the Myanmar Cave Documentation

Project supported JG in Myanmar, Krisztina Buczkó (HNHM) helped in using the scanning electronmicroscope.

We are indebted to The Biodiversity Heritage Library for the multitude of rare literature made available to us

(www.biodiversitylibrary.org). Fieldwork by Fred G. Thompson and KA in Thailand was funded by the National

Science Foundation (NSF), Division of Environmental Biology (DEB-8519386). This study was supported by the

Premium Post Doctorate Research Program, the Bolyai Research Scholarship of the Hungarian Academy of Scienc-

es, the Hungarian Research Fund (OTKA FK 135262) and grants from the SYNTHESYS Project (GB-TAF-2523)

to B.P-G.

References

Bavay, A. & Dautzenberg, P. (1900a) Diagnoses de coquilles nouvelles de l’Indo-Chine. Journal de Conchyliologie, 48, 108–

122.

Bavay, A. & Dautzenberg, P. (1900b) Description de coquilles nouvelles de l’Indo-Chine. Journal de Conchyliologie, 48, 435–

460.

Bavay, A. & Dautzenberg, P. (1912) Description de coquilles nouvelles de l’Indo-Chine. Journal de Conchyliologie, 60, 1–54.

Benson, W.H. (1856) Characters of seventeen new forms of the Cyclostomacea from the British provinces of Burmah, collected

by W. Theobald, Jun., Esq. The Annals and Magazine of Natural History, Series 2, 17, 225–233.

https://doi.org/10.1080/00222935608697501

Benson, W.H. (1857) Characters of Streptaulus a new genus and several species of the Cyclostomacea from Sikkim, the Khasi

Hills Ava and Pegu. The Annals and Magazine of Natural History, Series 2, 19, 201–211.

https://doi.org/10.1080/00222935708681840

Benson, W.H. (1859) A sectional distribution of the genus Alycæus, Gray, with characters of six new species and of other

Cyclostomidæ collected at Darjiling by W. T. Blanford, Esq. The Annals and Magazine of Natural History, Series 3, 3,

176–184.

Blanford, W.T. (1862) Contributions to Indian malacology, no. III. Descriptions of new operculated land-shells from Pegu,

Arakan and the Khasi Hills. Journal of the Asiatic Society of Bengal, 31, 135–144.

Blanford, W.T. (1863) Contributions to Indian malacology, no. IV. Descriptions of new land shells from Ava, and other parts of

Burma. Journal of the Asiatic Society of Bengal, 32, 319–327.

Blanford, W.T. (1864) On the classification of the Cyclostomacea of eastern Asia. The Annals and Magazine of Natural History,

PÁLL-GERGELY ET AL.

Series 3, 13(78), 441–465.

https://doi.org/10.1080/00222936408681635

Blanford, W.T. (1865) Contribution to Indian Malacology, No. V. Descriptions of new land shells from Arakan, Pegu, and Ava;

with notes on the distribution of described species. Journal of the Asiatic Society of Bengal, 34 (2), 66–105.

Dumrongrojwattana, P. & Maassen, W.J.M. (2008) Two new species of Alycaeus from eastern Thailand (Gastropoda, Caenogas-

tropoda, Cyclophoridae). The Thailand Natural History Museum Journal, 3 (1), 1–4.

Galimberti, F., Sanvito, S., Vinesi, M.C. & Cardini, A. (2019) “Nose-metrics” of wild southern elephant seal (Mirounga leonina)

males using image analysis and geometric morphometrics. Journal of Zoological Systematics and Evolutionary Research,

57 (3), 710–720.

https://doi.org/10.1111/jzs.12276

Godwin-Austen, H.H. (1882–1920) Land and freshwater Mollusca of India, including South Arabia, Baluchistan, Afghanistan,

Kashmir, Nepal, Burma, Pegu, Tenasserim, Malaya Peninsula, Ceylon and other islands of the Indian Ocean; Supplemen-

tary to Mssers Theobald and Hanley’s Conchologica Indica. Taylor and Francis, London, 257 + 442 pp.

https://doi.org/10.5962/bhl.title.18138

Gray, J.E. (1847) A list of the genera of recent Mollusca, their synonyma and types. Proceedings of the Zoological Society of

London, 15 (1847), 129–219.

Gude, G.K. (1921) The Fauna of British India including Ceylon and Burma. Mollusca. III. Land operculates (Cyclophoridae,

Truncatellidae, Assimineidae, Helicinidae). Taylor and Francis, London, 386 pp.

https://doi.org/10.5962/bhl.title.12890

Haines, W.A. (1858) Descriptions of four new species of terrestrial shells, from Siam. Annals of the Lyceum of Natural History

of New York, 6, 158–159.

https://doi.org/10.1111/j.1749-6632.1858.tb00358.x

Heude, R.P.M. (1885) Mémoires concernant l’histoire naturelle de l’empire chinois par des pères de la Compagnie de Jésus.

Notes sur les Mollusques terrestres de la vallée du Fleuve Bleu. Vol. III. Mission Catholique, Chang-Hai, 44 pp. [pp.

89–132]

Heude, R.P.M. (1890) Mémoires concernant l’histoire naturelle de l’empire chinois par des pères de la Compagnie de Jésus.

Notes sur les Mollusques terrestres de la vallée du Fleuve Bleu. Vol. IV. Mission Catholique, Chang-Hai, 64 pp. [pp.

125–188]

Inkhavilay, K., Sutcharit, C., Bantaowong, U., Chanabun, R., Siriwut, W., Srisonchai, R., Pholyotha, A., Jirapatrasilp, P. &

Panha, S. (2019) Annotated checklist of the terrestrial molluscs from Laos (Mollusca, Gastropoda). ZooKeys, 834, 1–166.

https://doi.org/10.3897/zookeys.834.28800

Jirapatrasilp, P., Páll-Gergely, B., Sutcharit, C. & Tongkerd, P. (2021): The operculate micro land snail genus Dicharax Kobelt

& Möllendorff, 1900 (Caenogastropoda, Alycaeidae) in Thailand, with description of new species. Zoosystematics and

Evolution, 97 (1), 1–20.

https://doi.org/10.3897/zse.97.59143

Kobelt, W. & Möllendorff, O.F. von (1900) Zur Systematik der Pneumonopomen. Nachrichtsblatt der Deutschen Malakozoolo-

gischen Gesellschaft, 32, 186.

Kuroda, T. (1951) On Awalycaeus abei gen. et. sp. nov. (Cyclophoridae). Venus, 16 (5–8), 73–74.

Liew, T.-S. & Schilthuizen, M. (2014) Association between shell morphology of micro-land snails (genus Plectostoma) and their

predator’s predatory behaviour. PeerJ, 2, e329.

https://doi.org/10.7717/peerj.329

Maassen, W.J.M. (2006) Remarks on Alycaeus species from South-East Asia, with the descriptions of four new species with

keeled shells (Gastropoda, Caenogastropoda, Cyclophoridae). Basteria, 70, 133–139.

Minato, H. (1988) A systematic and bibliographic list of the Japanese land snails. H. Minato, Shirahama, X + 294 pp., pls.

1–7.

Möllendorff, O.F. von (1886) Materialen zur Fauna for China. Jahrbücher der Deutschen Malakozoologischen Gesellschaft,

13, 156–210.

Möllendorff, O.F. von (1887) The landshells of Perak. Journal of the Asiatic Society of Bengal, 55, 299–316.

Möllendorff, O.F. von (1894) On a collection of land-shells from the Samui Islands, Gulf of Siam. Proceedings of the Zoological

Society of London, 1894, 146–156.

Möllendorff, O.F. von (1897) Neue Landschnecken von Java. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft,

29, 89–97.

Mörch, O.A.L. (1872) Synopsis molluscorum a cl. J. Reinhardt letorum in circumnavigatione orbis terrarum Danicæ navis

Galatheæ dictæ. Oversigt over de af Prof. J. Reinhardt paa Corvetten Galatheas Reise omkring Jorden indsamlede Blöddyr.

Videnskabelige meddelelser fra den Naturhistoriske forening i Kjöbenhavn, 1872, 9–35.

Páll-Gergely, B. & Asami, T. (2017) A new species of Metalycaeus hitherto undistinguished from M. vinctus (Pilsbry, 1902).

Venus, 75 (1–4), 1–16.

Páll-Gergely, B. & Hunyadi, A. (2018) Four new cyclophoroid species from Thailand and Laos (Gastropoda: Caenogastropoda:

Alycaeidae, Diplommatinidae, Pupinidae). Zoosystema, 40 (4), 59–66.

https://doi.org/10.5252/zoosystema2018v40a3

Páll-Gergely, B., Hunyadi, A., Đỗ, Đ.S., Naggs, F. & Asami, T. (2017) Revision of the Alycaeidae of China, Laos and Vietnam

(Gastropoda: Cyclophoroidea) I: The genera Dicharax and Metalycaeus. Zootaxa, 4331 (1), 1–124.

https://doi.org/10.11646/zootaxa.4331.1.1

Páll-Gergely, B., Sajan, S., Tripathy, B., Meng, K., Asami, T. & Ablett, J. (2020) Genus-level revision of the Alycaeidae, with a

catalog of the species (Gastropoda: Cyclophoroidea). ZooKeys, 981, 1–220.

https://doi.org/10.3897/zookeys.981.53583

Panha, S. & Burch, J.B. (1997) A new cave dweller of the genus Alycaeus in Thailand (Prosobranchia: Cyclophoracea: Cyclo-

phoridae). Malacological Review, 30, 119–122.

Panha, S. & Patamakanthin, S. (2001) A new Alycaeus species from southern Thailand (Prosobranchia: Cyclophoracea: Cyclo-

phoridae). Of Sea and Shore, 23 (4), 189–190.

Pilsbry, H.A. (1900) Notices of new Japanese land shells. Proceedings of the Academy of Natural Sciences of Philadelphia, 52,

381–384.

Pilsbry, H.A. (1902) New land molluscs from the Japanese Empire. The Nautilus, 16: 53–57.

Reinhardt, O. (1877) [Herr Reinhardt legte eine Anzahl japanischer...]. In: Peters, W. (1877) Sitzungs-Bericht der Gesellschaft

naturforschender Freunde zu Berlin vom 20. März 1877. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu

Berlin, 1877, pp. 67–70

Rensch, B. (1933) Die Molluskenfauna von Pulu Weh und ihre zoogeographischen Beziehungen. Zoologischer Anzeiger Leipzig,

102, 195–208.

Scopoli, J.A. (1777) Introductio ad historiam naturalem, sistens genera lapidum, plantarum et animalium hactenus detecta,

caracteribus essentialibus donata, in tribus divisa, subinde ad leges naturae. Introductio ad historiam naturalem. Apud

Wolfgangum Gerle, Prague, 506 pp.

https://doi.org/10.5962/bhl.title.10827

Simroth, H. (1891) Über das Vagulinidengenus Atopos n. g. Zeitschrift für Wissenschaftliche Zoologie, 52 (4), 593–615.

https://doi.org/10.1002/ange.18910042008

Theobald, W. (1870) Descriptions of new species of land shells from the Shan States and Pegu. Journal of the Asiatic Society

of Bengal, 39, 395–402.

Thiele, J. (1929) Handbuch der systematischen Weichtierkunde. Teil 1. Verlag von Gustav Fischer, Jena, 376 pp.

Varga, A. (1974) Eine neue Chamalycaeus-Art aus Vietnam (Gastropoda: Cyclophoridae, Alycaeninae). Folia Historico Natu-

ralia Musei Matraensis, 2, 165–167.

Yang, H., Fan, Z., Qiao, D. & He, J. (2012) Description of four landsnails from China. Shell Discoveries, 1 (1), 32–33.

Zilch, A. (1957) Die Typen und Typoide des Natur-Museums Senckenberg, 20: Mollusca, Cyclophoridae, Alycaeinae. Archiv

für Molluskenkunde, 86 (4/6), 141–150.

Two new species of Dicharax Kobelt & Möllendorff, 1900 from Myanmar and one from Thailand (Gastropoda: Caenogastropoda: Alycaeidae)

Article

Full-text available

Nov 2022

In this paper, three new species of the alycaeid genus Dicharax Kobelt & Möllendorff, 1900 are described, namely Dicharax floridus n. sp., Dicharax spatiosus n. sp. (Both from Shan State, Myanmar) and Dicharax kosztarabi n. sp. (from Thailand). All three new species are known from their holotypes. http://zoobank.org/28168F06-CFBF-405F-90F7-A3399060D88C

Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) II: The genera Alycaeus and Pincerna

Article

Full-text available

Mar 2023
ZOOTAXA

Barna Páll-Gergely

This is the second part of the revision of Chinese, Lao and Vietnamese Alycaeidae (superfamily Cyclophoroidea), and covers the genera Alycaeus and Pincerna. Threemnew species are described: Alycaeus goliath Páll-Gergely, n. sp. (central Laos), Pincerna acroptychia n. sp. (Ha Giang Province, northern Vietnam), Pincerna viginticostatus n. sp. (Lạng Sơn Province, northern Vietnam). Pincerna vallis Z.-Y. Chen & M. Wu, 2020 is treated as a junior synonym of Pincerna costulosus (Bavay & Dautzenberg, 1912), and Pincerna clausus D. S. Do & T. S. Nguyen, 2022 as a synonym of Pincerna vanbuensis (Bavay & Dautzenberg, 1900).

Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae)

Article

Full-text available

Feb 2023

The Southeast Asian genus Angustopila, currently comprising 13 nominal species, encompasses the world’s tiniest land snails. This work shows that there are far more species than previously suspected, and that this genus is in fact a very speciose group of tiny snails widely distributed in Southeast Asia. Angustopila is revised based on type material of known species as well as 211 samples newly collected in China, Laos, Myanmar, Thailand and Vietnam. Altogether, 53 species and one subspecies are recognised, of which 42 species and subspecies are new to science.

Caenogastropoda and Stylommatophora (Gastropoda) from the mid-Miocene Zhangpu amber of East Asia

Article

Jul 2022
Palaeoworld

Four gastropod species including two new species (?Tinnyea sp., Cyclophoridae gen. et sp. indet., Metalycaeus fossilis n. sp., and Tortaxis zhangpuensis n. sp.) are described from the mid-Miocene Zhangpu amber. Among them, ?Tinnyea sp. is potentially the first fossil record of this group in lake systems of East Asia, outside of Mediterranean and Paratethys areas. Tortaxis zhangpuensis n. sp. and Metalycaeus fossilis n. sp. are likely the oldest representatives of respective genera. Despite Tortaxis zhangpuensis n. sp. being a juvenile shell, its whorls are taller and more convex in comparison to congeners, and from around 3.75th whorl onwards the sub-sutural area of whorls displays a crenulated pattern. Metalycaeus fossilis n. sp. has a spirally striated protoconch (the key diagnostic character of the genus), and with strong, widely spaced R1 ribs, short R2, which distinguishes it from its congeners.

The operculate micro land snail genus Dicharax Kobelt & Möllendorff, 1900 (Caenogastropoda, Alycaeidae) in Thailand, with description of new species

Article

Full-text available

Jan 2021

This study reviews the Dicharax species in Thailand. Altogether ten Dicharax species are reported, four of which are new to science and described herein. They are Dicharax borealis Jirapatrasilp & Páll-Gergely sp. nov., Dicharax burchi Jirapatrasilp & Páll-Gergely sp. nov., Dicharax panhai Jirapatrasilp & Páll-Gergely sp. nov. and Dicharax pongrati Jirapatrasilp & Tongkerd sp. nov. Alycaeus davisi Godwin-Austen, 1914 is regarded as a junior subjective synonym of Alycaeus cucullatus Theobald, 1870 (= D. cucullatus) based on a similar depressed-conical shell shape, a long sutural tube and a sharp swelling behind the peristome. Furthermore, the type locality of Alycaeus pratatensis Panha & Burch, 1997 (= D. pratatensis) had to be amended. Most important characters to distinguish Dicharax species are the general shell shape and relative lengths of teleoconch regions, whereas the spiral striation of R1, the shape of swelling of R3, the outer peristome crenulation and protrusion, and the exterior opercular sculpture show large intraspecific variability.

Genus-level revision of the Alycaeidae (Gastropoda, Cyclophoroidea), with an annotated species catalogue

Article

Full-text available

Oct 2020

412 species-group names (including 11 replacement names), and 14 genus-group names of the Alycaeidae have been introduced to date. Type materials of 85% (336) of the known species and subspecies were examined, a further 5% (19) of the taxa were studied using available non-type material, and for another 6% (22) the original descriptions were sufficiently detailed to evaluate their taxonomic status. Only 3% of the taxa (12) could not be examined. Special attention was paid to the sculpture of the embryonic whorls and the sutural tube-microtunnel system in order to provide a novel classification for this group. In this study 363 taxa (320 species or 43 subspecies) are accepted within the family Alycaeidae. Of these, 22 have been described by the lead author and his coauthors in previous publications. In addition, there are 18 species that were formerly classified in Cycloryx and now belong to Pincerna due to its synonymy with Cycloryx. Among the remaining 323 species, 209 (65%) are transferred here to another genus, whilst 114 (35%) have remained in their original genus. Seven genera are accepted. While some questions (e.g., the distinction between Pincerna and Alycaeus) remained unanswered, this revision made three main achievements: (1) The Dicharax species were identified based on the absence of spiral striation on the entire shell; (2) the Metalycaeus species were identified based on the spiral striation of the protoconch; (3) and Stomacosmethis was separated from Alycaeus based on the extremely short sutural tube. Five nominal species are being synonymised with other species, and eight species are now treated as subspecies. The following replacement names are proposed: Dioryx urnula niosiensis Páll-Gergely, nom. nov. for Alycaeus urnula var. daflaensis Godwin-Austen, 1914; Dioryx urnula rotundus Páll-Gergely, nom. nov. for Alycaeus urnula var. globosus Godwin-Austen, 1914; Pincerna crenilabris juttingae Páll-Gergely, nom. nov. for Alycaeus crenilabris laevis van Benthem Jutting, 1959; Pincerna crenilabris korintjiensis Páll-Gergely, nom. nov. for Alycaeus crenilabris latecostatus van Benthem Jutting, 1959; Dicharax conicus jatingaensis Páll-Gergely, nom. nov. for Alycaeus conicus var. nanus Godwin-Austen, 1914; Metalycaeus godwinausteni Páll-Gergely, nom. nov. for Alycaeus neglectus Godwin-Austen, 1914; and finally Metalycaeus suhajdai Páll-Gergely, nom. nov. for Alycaeus varius Godwin-Austen, 1914.

Annotated checklist of the terrestrial molluscs from Laos (Mollusca, Gastropoda)

Article

Full-text available

Apr 2019

The land area of Laos is composed of a large variety of undisturbed habitats, such as high mountainous areas, huge limestone karsts and the lower Mekong Basin. Therefore, Laos is expected to have a high species diversity, especially for the land snails. However, with respect to research on malacology, Laos is probably the least well-researched area for land snail diversity in Indochina (including Laos) over the past few centuries. The handful of species lists have never been systematically revised from the colonial period to the present, so these classifications are outdated. Herein we present the first comprehensive annotated checklist with an up-to-date systematic framework of the land snail fauna in Laos based on both field investigations and literature surveys. This annotated checklist is collectively composed of 231 nominal species (62 ‘prosobranch’ and 169 heterobranches), of which 221 nominal species are illustrated. The type specimens of 143 species from several museum collections and/or 144 species of newly collected specimens are illustrated. There are 58 species recorded as new to the malacofauna of the country, and two new replacement names are proposed as Hemiplecta lanxangnica Inkhavilay and Panha, nomen novum (Ariophantidae) and Chloritis khammouanensis Inkhavilay and Panha, nomen novum (Camaenidae). Four recently described species of the genus Amphidromus from Laos, “thakhekensis”, “richgoldbergi”, “attapeuensis” and “phuonglinhae” are synonymized with previously described species. In addition, thirteen nominal species are listed as uncertain records that may or may not occur in Laos. This annotated checklist may inspire malacologists to carry on systematic research in this region.

“Nose-metrics” of wild southern elephant seal ( Mirounga leonina ) males using image analysis and geometric morphometrics

Article

Full-text available

Mar 2019

The elephant seal (genus Mirounga) proboscis is a textbook example of an exaggerated secondary sexual trait, whose function is debated. The proboscis can be related to sexual status advertising, emission of aggressive vocalizations, and/or female mating choice. The study of the proboscis is complicated, because it is a soft trait that needs to be studied when males vocalize and it is thus expanded. Here, we combined field stimulation experiments, 2D photogrammetry, and geometric morphometrics, to study the proboscis of wild elephant seals in natural conditions. The goal of our study was twofold: (a) to demonstrate that photogrammetry and geometric morphometrics can be effectively applied in the field to wild, large, non-sedated mammals; (b) to study the proboscis shape development during maturation. We found that it is possible to accurately estimate the proboscis size and shape using photographs of vocalizing males taken in the field. Moreover, we showed that mature and non-mature males differ not only in proboscis size but also in its shape, a difference that is largely allometric and can have important effects on the frequency structure and individual signature of male vocalizations. These results open new avenues for future research on this enigmatic structure, its function in aggressive displays and potential role in sexual selection, and also exemplify a very promising approach, that could be applied in field studies of other large mammals.

Four new cyclophoroid species from Thailand and Laos (Gastropoda: Caenogastropoda: Alycaeidae, Diplommatinidae, Pupinidae)

Article

Full-text available

Feb 2018

This paper describes four new species, namely Dicharax caudapiscis n. sp., Dicharax stuparum n. sp. (both family Alycaeidae Blanford, 1864), Pseudopomatias caligosus n. sp. (family Pupinidae L. Pfeiffer, 1853) and Arinia (Notharinia) boucheti Páll-Gergely, n. sp. (family Diplommatinidae Benson, 1849). The first three were recently collected in northern Thailand, whereas the latter one was collected in Laos by Edmond Saurin, and later also found in the collection of the Muséum national d'Histoire naturelle, Paris. © Publications scientifiques du Muséum national d'Histoire naturelle, Paris.

A New Species of Metalycaeus Hitherto Undistinguished from M. vinctus (Pilsbry, 1902) (Gastropoda: Cyclophoroidea: Alycaeidae)

Article

Full-text available

Dec 2017

We examined specimens which have hitherto been identified as the operculate land snail Metalycaeus vinctus (Pilsbry, 1902) (formerly Chamalycaeus vinctus) in the National Museum of Nature and Science, Tsukuba, Japan. We found among these specimens another morphologically distinct taxon. Field investigation and examination of other newly-collected specimens confirmed that the real Metalycaeus vinctus lives in the northern part of Tanegashima Island, whereas the new species, Metalycaeus minatoi Páll-Gergely n. sp. mainly inhabits the southern part. The two species can be distinguished mainly by the morphology of the body whorl surface along the sutural tube: that of Metalycaeus minatoi n. sp. is more densely ribbed (26-41 ribs, mean: 33.0) and has lower ribs, which results in a nearly smooth shell surface whereas Metalycaeus vinctus (17-23 ribs, mean: 19.6) has elevated and sharp ribs. A third species, also reported from this island, Dicharax (?) tanegashimae (Pilsbry, 1902) was also found by us. The morphology of the penis, radula, operculum, and shell morphology of both Metalycaeus species, and penis morphology of D. tanegashimae are described and illustrated.

Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) I: The genera Dicharax and Metalycaeus

Article

Full-text available

Oct 2017

This is the first part of the revision of the Alycaeidae of China, Laos and Vietnam. Here we revise the species hitherto classified in Chamalycaeus Möllendorff, 1897 (genera Dicharax and Metalycaeus in this study). We show that no Chamalycaeus live in the region, and the alycaeid species of the investigated region can be classified into five genera: Alycaeus Baird, 1850, Dicharax Kobelt & Möllendorff, 1900, Dioryx Benson, 1859, Metalycaeus Pilsbry, 1900 and Pincerna Preston, 1907. We propose Dioryx dautzenbergi Páll-Gergely nom. nov. as a replacement name for Alycaeus (Dioryx) major Bavay & Dautzenberg, 1900, non Alycæus (Dioryx) granum var. major Godwin-Austen, 1893. Alycaeus anceyi Mabille, 1887, A. eydouxi Venmans, 1956, A. mouhoti L. Pfeiffer, 1862, A. rolfbrandti Maassen, 2006 and A. vanbuensis Bavay & Dautzenberg, 1900 are retained in Alycaeus. Alycaeus costulosa Bavay & Dautzenberg, 1912 and A. maolanensis Luo, Zhang & Zhuo 2009 were transferred to Pincerna. We examined newly collected specimens and the type specimens of all species with the exception of the following: A. elevatus Heude, 1886, A. expansus Heude, 1890, A. neglectus Heude, 1885, Chamalycaeus libonensis Chen, Li & Luo 2003, C. panshiensis Chen, 1989, C. tangmaiensis Chen & Zhang, 2001, C. zayuensis Zhang, Chen & Zhou, 2008. Fifteen new species are described as follows: Dicharax (?) abdoui Páll-Gergely, n. sp., Dicharax (?) alticola Páll-Gergely & Hunyadi n. sp., Dicharax (?) ellipticus Páll-Gergely n. sp., Dicharax (?) immaculatus Páll-Gergely n. sp., Dicharax bison Páll-Gergely & Hunyadi n. sp., Dicharax draco Páll-Gergely & Hunyadi n. sp., Dicharax imitator Páll-Gergely & Hunyadi n. sp., Dicharax microcostatus Páll-Gergely n. sp., Dicharax micropolitus Páll-Gergely & Hunyadi n. sp., Dicharax robustus Páll-Gergely & Hunyadi, n. sp., Metalycaeus (?) awalycaeoides Páll-Gergely & Hunyadi n. sp., Metalycaeus (?) ibex Páll-Gergely & Hunyadi n. sp., Metalycaeus laosensis Páll-Gergely n. sp., Metalycaeus oharai Páll-Gergely & Hunyadi n. sp., Metalycaeus (?) okuboi Páll-Gergely & Hunyadi, n. sp. A total of twelve names are synonymised with valid species. In this revision we payed special attention to conchological characters hitherto neglected, such as the fine sculpture of the embryonic whorls and the fine structure of the microtunnels along the breathing tube. We described the radula and penis morphology of five Dicharax species.

Association between shell morphology of micro-land snails (genus Plectostoma) and their predator’s predatory behaviour

Article

Full-text available

Apr 2014

Predator-prey interactions are among the main ecological interactions that shape the diversity of biological form. In many cases, the evolution of the mollusc shell form is presumably driven by predation. However, the adaptive significance of several uncommon, yet striking, shell traits of land snails are still poorly known. These include the distorted coiled "tuba" and the protruded radial ribs that can be found in micro-landsnails of the genus Plectostoma. Here, we experimentally tested whether these shell traits may act as defensive adaptations against predators. We characterised and quantified the possible anti-predation behaviour and shell traits of Plectostoma snails both in terms of their properties and efficiencies in defending against the Atopos slug predatory strategies, namely, shell-apertural entry and shell-drilling. The results showed that Atopos slugs would first attack the snail by shell-apertural entry, and, should this fail, shift to the energetically more costly shell-drilling strategy. We found that the shell tuba of Plectostoma snails is an effective defensive trait against shell-apertural entry attack. None of the snail traits, such as resting behaviour, shell thickness, shell tuba shape, shell rib density and intensity can fully protect the snail from the slug's shell-drilling attack. However, these traits could increase the predation costs to the slug. Further analysis on the shell traits revealed that the lack of effectiveness in these anti-predation shell traits may be caused by a functional trade-off between shell traits under selection of two different predatory strategies.

XXIII.-Descriptions of Four New Species of Terrestrial Shells, from Siam

Article

Sep 2009

Wm. A. Haines

Handbuch der Systematischen Weichtierkunde

Article

Jan 1929

J. Thiele

Nineteen new species of Alycaeidae from Myanmar and Thailand (Gastropoda: Caenogastropoda: Cyclophoroidea)

Abstract and Figures

Recommendations

New and little-known species of continental Southeast Asian Clausiliidae (Gastropoda: Pulmonata)

Two new species of Dicharax Kobelt & Möllendorff, 1900 from Myanmar and one from Thailand (Gastropod...

The operculate micro land snail genus Dicharax Kobelt & Möllendorff, 1900 (Caenogastropoda, Alycaeid...

New taxa of Diapheridae Panha & Naggs in Sutcharit et al., 2010 from Laos and Thailand (Gastropoda:...

Revision of the Alycaeidae of China, Laos and Vietnam (Gastropoda: Cyclophoroidea) II: The genera Al...