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Discovery of Myxostoma petiverianum Wood, 1828 (Gastropoda: Caenogastropoda: Cyclophoroidea: Cyclophoridae) on Hòn Cau, Vietnam

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The land snail Myxostoma petiverianum is previously known from only a few localities in Cambodia and Vietnam. We report on a new record of Myxostoma petiverianum from Hòn Cau, an island in the Côn Đảo Archipelago, south-eastern Vietnam.
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Volume: 50 THE FESTIVUS ISSUE 2
ISSN 0738-9388
110
Discovery of Myxostoma petiverianum Wood, 1828 (Gastropoda:
Caenogastropoda: Cyclophoroidea: Cyclophoridae) on Hòn Cau, Vietnam
Scott J. Trageser 1, 5, Ash Wiscovitch 2, and Junn Kitt Foon 3, 4
112525 E Arbor Vista Blvd, Tucson, Arizona 85749, United States of America;
trageser.scott@gmail.com
2160 Keonekai Rd, Kihei, Hawaii 96753, United States of America; ash.wisco@gmail.com
3Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan
UMS, 88400 Kota Kinabalu, Sabah, Malaysia;
4Rimba, 22-3A, Casa Kiara 2, Jalan Kiara 5, 50480 Kuala Lumpur, Malaysia; jk@rimbaresearch.org
5Corresponding author
ABSTRACT The land snail Myxostoma petiverianum is previously known from only a few
localities in Cambodia and Vietnam. We report on a new record of Myxostoma petiverianum from
Hòn Cau, an island in the Côn Đảo Archipelago, south-eastern Vietnam.
KEYWORDS Myxostoma petiverianum, Vietnam, Hòn Cau, Côn Đảo Archipelago.
INTRODUCTION
The species Myxostoma petiverianum Wood,
1828 is until recently, one of the lesser known
land snails of Southeast Asia. A flurry of
scientific attention on the land snails of southern
Vietnam and neighbouring areas in recent years
have led to renewed malacological attention on
M. petiverianum. Egorov (2016) recorded and
described the shell and radula morphology of M.
petiverianum from Kep National Park in
Cambodia and Côn Sơn in Vietnam while Foon
(2016) described a new subspecies Myxostoma
petiverianum tenggolense Foon, 2016 from
Peninsular Malaysia (for nomenclatural
emendation, see Bouchet, 2016). Nguyễn and
Nguyễn (2016) reported the presence of M.
petiverianum (under the name Cyclotus
fasciatus Martens, 1864) from Hòn Tre, An Sơn
and Lại Sơn islands off the coast of Rạch Giá,
south-western Vietnam. Raheem et al. (2017)
included a photographed specimen of M.
petiverianum in their pictorial guide to
Vietnamese land snails.
In the midst of these publications, a picture of a
snail photographed by the first author in 2014
on Hòn Cau, Vietnam and uploaded onto an
internet-based citizen science platform was
spotted by the third author. Communication was
initiated between the authors and it was
confirmed that the photographed snail was
indeed M. petiverianum based on conchological
and anatomical comparisons with museum
collection specimens and literature. The
discovery of M. petiverianum on Hòn Cau, Côn
Đảo Archipelago is herein reported for
permanent scientific record.
Observation and identification of Myxostoma
petiverianum on Hòn Cau, Vietnam
During the citizen science project titled “Con
Dao Land and Sea” organised under the
Biodiversity PEEK program, the first and
second authors were exploring the rainforests of
Hòn Cau (8°41.337'N, 106°44.266'E), Côn Đảo
Archipelago, Vietnam when they came across
an unidentified land snail on August 3, 2014.
This unidentified land snail was photographed
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(Figure 1) and submitted to the citizen science
platform iNaturalist (www.inaturalist.org). This
photograph was later examined by the third
author and cross-checked with descriptions in
literature and museum collection lots (see Foon,
2016). Note that Hòn Cau is a satellite island of
Côn Sơn [= Pulo Condore] (Figure 2), the latter
of which is the most well-known locality of M.
petiverianum based on historical and museum
records (Egorov 2016, Foon 2016).
There are many discernible characters in the
photographed individual which identify it as
Myxostoma petiverianum. First, the operculum
is thick, horny, has a periphery adorned with
somewhat loosely overlapping brown lamellae
at the exterior and a raised interior where the
columellar muscle is attached to. Second, the
shell has a peripheral dark brown band set
against a light brown base as well as a
peristome that is dark brown, thickened and
reflected. Also, the aperture is orientated
ventrally and obliquely with respect to the
coiling axis. Third, the living animal colour,
fine blackish-greyish mottling as well as the
genital groove match that of the living sub-adult
illustrated in Plate 1, Figure G in Egorov (2016).
Besides these, historical records of land snails
from Côn Đảo archipelago (Martens, 1872)
suggest no species are closely-related to
Myxostoma petiverianum except Cyclcophorus
volvulus Müller, 1774. Yet, Cyclophorus
volvulus can be easily distinguished from M.
petiverianum by its shell which has much
thicker, dark brown spiral band below the
periphery, an aperture that is orientated
somewhat parallel to the coiling axis and a
rather tall spire with sharp apex (Pfeiffer, 1846),
none of which characterises the M.
petiverianum individual in Figure 1.
Figure 1. Photograph of a living adult Myxostoma petiverianum,
taken on Hòn Cau, Vietnam. (Photograph by: Scott J. Trageser)
DISCUSSION
This is the first ever photograph of a live adult
Myxostoma petiverianum (Figure 1). This new
locality record along with all known records of
M. petiverianum in the literature (Egorov, 2016,
Foon, 2016, Nguyễn & Nguyễn, 2016), suggests
that the species has a distribution limited to the
islands and hills of the Mekong Delta region
(Figure 2).
The discovery and identification of this land
snail via citizen science demonstrates the
usefulness of citizen science initiatives in
addressing knowledge gaps in under-explored
regions with potentially high biodiversity.
ACKNOWLEDGEMENTS
The first and second authors would like express
their gratitude to the People's Committee of Bà
Rịa-Vũng Tàu Province and the Management
Board of Côn Đảo National Park for permission
to visit Hòn Cau and to Con Dao Scuba Diving
Center for their gracious hospitality and expert
guiding services. The third author would like to
thank Dinarzarde Raheem (Natural History
Museum, London) for providing a copy of the
Raheem et al. (2017) illustrated guide and
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discussions on Myxostoma petiverianum
specimens in the NHM collection. All authors
also thank the reviewers for their constructive
comments on the manuscript.
REFERENCES
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Figure 2. Maps showing known localities of Myxostoma petiverianum in the literature (Egorov, 2016, Foon, 2016, Nguyễn & Nguyễn,
2016) as well as records from this study. A. Overview of the Mekong Delta, with boxes indicating areas zoomed in for figures B and C.
B. Localities with M. petiverianum in the Côn Đảo archipelago. C. Localities with M. petiverianum at south-western Vietnam and
Cambodia. Relief basemap by Hans Braxmeier (maps-for-free.com).
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Myxostoma petiverianum tenggolensis, new subspecies, is described from Pulau Tenggol, State of Terengganu, Peninsular Malaysia, based on shell characteristics. Myxostoma petiverianum tenggolensis is distinguished from its closest congener and nominal subspecies Myxostoma petiverianum petiverianum (Wood, 1828), by a rather uniformly brown shell with scarce zigzag patterns on the dorsal side and lack of peripheral banding. The discovery is the first record of Myxostoma in Peninsular Malaysia and represents a 500 km southwards range extension of the genus.
Myxostoma petiverianum tenggolense Foon
  • P Bouchet
Bouchet, P. 2016. Myxostoma petiverianum tenggolense Foon, 2016. In: MolluscaBase (2017) World Register of Marine Species. http://www.marinespecies.org/aphia.php?p=t axdetails&id=932067 [22 January 2018].
A redescription and new distributional record of Myxostoma petiverianum (Wood, 1828) (Gastropoda, Cyclophoridae), poorly known species from South-East Asia
  • R V Egorov
Egorov, R.V. 2016. A redescription and new distributional record of Myxostoma petiverianum (Wood, 1828) (Gastropoda, Cyclophoridae), poorly known species from South-East Asia. Conchylia 46:97-102.
Conchylien von Cook's Reisen
  • E Von Martens
Martens, E. von. 1872. Conchylien von Cook's Reisen. Malakozoologische Blätter 19:1-48.
Vermium terrestrium etfluviatilium, sen animalium infusoriorum, helminthicorum, et testaceorum, non marinorum
  • O F Müller
Müller, O.F. 1774. Vermium terrestrium etfluviatilium, sen animalium infusoriorum, helminthicorum, et testaceorum, non marinorum, succincta historia, Vol. 2, Testacea. Heineck et Faber, Havnie [= Copenhagen] et Lipsiae [= Leipzig]. 214 pp.
First data about landsnail in the island of Kien Hai district -Kien Giang province
  • T T V B Nguyễn
  • Nguyễn
Nguyễn, T.T. & V.B. Nguyễn. 2016. First data about landsnail in the island of Kien Hai district -Kien Giang province. Tạp chí Khoa học Trường Đại học Cần Thơ, 45:97-109. [in Vietnamese]
Die gedeckelten Lungenschnecken (Helicinace et Cyclostomacea) in Abbildungen nach der Natur mit Beschreibungen. Systematisches Conchylien-Cabinet von Martini und Chemnitz Band
  • L Pfeiffer
Pfeiffer, L. 1846. Die gedeckelten Lungenschnecken (Helicinace et Cyclostomacea) in Abbildungen nach der Natur mit Beschreibungen. Systematisches Conchylien-Cabinet von Martini und Chemnitz Band 1, 19(1):1-400.
Supplement to the index testaceologicus; or a catalogue of shells, British and foreign
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Wood, W. 1828. Supplement to the index testaceologicus; or a catalogue of shells, British and foreign. William Wood, London, 59 pp.