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

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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.
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https://doi.org/10.11646/zootaxa.4973.1.1
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ZOOTAXA
ISSN 1175-5326 (print edition)
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Accepted by M. Harzhauser: 19 Apr. 2021; published: 18 May 2021
4973
ZOOTAXA
Magnolia Press
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Zootaxa 4973 (1): 001–061
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Copyright © 2021 Magnolia Press Monograph
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.
2 · Zootaxa 4973 (1) © 2021 Magnolia Press
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
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ISSN 1175-5326 (Print edition)
ISSN 1175-5334 (Online edition)
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 3
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.
4 · Zootaxa 4973 (1) © 2021 Magnolia Press
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
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 5
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.
6 · Zootaxa 4973 (1) © 2021 Magnolia Press
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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 7
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.
8 · Zootaxa 4973 (1) © 2021 Magnolia Press
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.
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 9
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.
10 · Zootaxa 4973 (1) © 2021 Magnolia Press
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.
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 11
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).
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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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 13
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.
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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
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 15
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).
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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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 17
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.
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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.
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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
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(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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 21
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.
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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-
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 23
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.
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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.
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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.
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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).
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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).
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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.
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 29
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).
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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-
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 31
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).
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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,
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 33
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,
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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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 35
FIGURE 26. Dicharax notus (Godwin-Austen, 1914). A: UF 347139; B: site JG11 (operculum); C: site 2018/41 (operculum
in situ).
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36 · Zootaxa 4973 (1) © 2021 Magnolia Press
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;
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 37
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
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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.
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 39
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.
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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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 41
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
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(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;
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 43
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).
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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).
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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
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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
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 47
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.
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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).
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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.
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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).
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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).
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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
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 53
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.
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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).
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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).
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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
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 57
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.
58 · Zootaxa 4973 (1) © 2021 Magnolia Press
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).
NEW SPECIES OF ALYCAEIDAE FROM MYANMAR & THAILAND Zootaxa 4973 (1) © 2021 Magnolia Press · 59
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.
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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.
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