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Thampramon tonvuthi, a new genus and new species of cavernicolous crab (Crustacea: Decapoda: Brachyura: Potamidae) from Thailand

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  • SeubNakasathien Foundation

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A new genus and species of potamid cavernicolous crab, Thampramon tonvuthi sp. nov., is described from Thailand. While superficially similar to Tiwaripotamon Bott, 1970, Phaibulamon Ng, 1992, and Nemoron Ng, 1996, the new genus possesses a unique combination of morphological characters including a distinctive carapace form, possession of a relatively long third maxilliped exopod, long ambulatory legs and a unique male first gonopod.
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Accepted by P. Castro: 11 Apr. 2013; published: 16 May 2013
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http://dx.doi.org/10.11646/zootaxa.3652.2.4
http://zoobank.org/urn:lsid:zoobank.org:pub:02E6C74A-4381-42F5-87F5-75ECEBFE2EC9
Thampramon tonvuthi, a new genus and new species of cavernicolous crab
(Crustacea: Decapoda: Brachyura: Potami
dae) from Thailand
PETER K. L. NG
1,3
& CHAVALIT VIDTHAYANON
2
1
Raffles Museum of Biodiversity Research, Faculty of Science, National University of Singapore, 14 Science Drive 4, 117543 Republic
of Singapore
2
Environment Programme, Mekong River Commission Secretariat, Fa Ngum Road, Ban Sithan Noua, Vientian 01000, Laos.
E-mail: chavalit@mrcmekong.org
3
Corresponding author. E-mail: peterng@nus.edu.sg
Abstract
A new genus and species of potamid cavernicolous crab, Thampramon tonvuthi sp. nov., is described from Thailand.
While superficially similar to Tiwaripotamon Bott, 1970, Phaibulamon Ng, 1992, and Nemoron Ng, 1996, the new genus
possesses a unique combination of morphological characters including a distinctive carapace form, possession of a rela-
tively long third maxilliped exopod, long ambulatory legs and a unique male first gonopod.
Key words: Crustacea, Brachyura, Potamidae, taxonomy, cavernicoles, new genus, new species, Thailand
Introduction
The freshwater crabs of the families Potamidae Ortmann, 1893, and Gecarcinucidae Rathbun, 1904, are extremely
diverse in Thailand and more than 100 species have been recorded so far (updated from Yeo & Ng 1999, 2007).
This is the highest in Indochina, which has an estimated 200 known species (see Yeo & Ng 1999; Cumberlidge et
al. 2009). Despite this diversity, very few species are known from caves. For gecarcinucids, only Phricotelphusa
deharvengi Ng, 1988 (southern Thailand), has been reported as a cavernicole, although it is unlikely to be an
obligate troglobite. Only three species of potamids are known only from caves so far: Phaibulamon stilipes Ng,
1992 (northwestern Thailand), Erebusa calobates Yeo & Ng, 199 (southern Laos), and Tiwaripotamon edostilus
Ng & Yeo, 2001 (northern Vietnam). One species, Nemoron nomas Ng, 1996, has been found in caves in central
Vietnam but it also occurs in the adjacent forests.
We here describe a new genus and new species of a cavernicolous potamid, Thampramon tonvuthi gen. et. sp.
nov. from Thailand. While superficially resembling Phaibulamon stilipes, it has a suite of characters that indicate it
should be placed in its own genus. In the general form of the carapace, mouthparts and male gonopods,
Thampramon tonvuthi gen. et. sp. nov. appears to be closest to Nemoron nomas from Vietnam. Specimens
examined are deposited in the National Inland Fisheries Institute (NIFI), Thai Department of Fisheries, Bangkok,
Thailand; and Zoological Reference Collection (ZRC) of the Raffles Museum of Biodiversity Research, National
University of Singapore. The abbreviations G1 and G2 are used for the male first and second gonopods,
respectively. Measurements provided (in millimetres) are of the carapace width and length, respectively.
Systematic account
Family Potamidae Ortmann, 1896
Thampramon gen. nov.
Diagnosis. Carapace subquadrate, surfaces relatively smooth; anterolateral margin distinctly convex, serrated
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266 · Zootaxa 3652 (2) © 2013 Magnolia Press
(Figs. 1A, 2A–C); epigastric and postorbital cristae distinct (Figs. 1A, 2A–C); external orbital tooth separated from
anterolateral margin by a deep V-shaped cleft (Figs. 1A, 2A–C); median lobe of posterior margin of epistome
broadly triangular (Fig. 3A–C); third maxilliped with relatively long ischium (Fig. 7A); exopod of third maxilliped
relatively long, reaching beyond upper edge of ischium with long flagellum (Fig. 7A, B); ambulatory legs
conspicuously long (Figs. 1A, B, 2A–C, 6A); lateral margins of male telson concave (Fig. 4A, D); G1 relatively
slender, almost straight with pronounced dorsal flap (Fig. 7C, D); basal part of G2 subquadrate (Fig. 7E).
Etymology. The name is derived from the Thai name for the cave at the type locality, “Tham Pra” with a
common suffix for potamid genera, “-mon”, from the type genus of the family, Potamon. Gender neuter.
Remarks. While Thampramon gen. nov. is superficially similar to Phaibulamon Ng, 1992, in general
appearance (especially with regards to the long ambulatory legs), the two are unlikely to be closely related.
Thampramon differs in the following aspects: carapace surface relatively smooth overall (Figs. 1A, 2A–C)
(covered with numerous small, rounded granules in Phaibulamon, cf. Ng 1992: fig. 1); external orbital tooth
separated from anterolateral margin by a deep V-shaped cleft (Figs. 1A, 2A–C) (separated by simple notch in
Phaibulamon, cf. Ng 1992: fig. 1); epigastric cristae well developed and postorbital cristae sharp (Figs. 1A, 2A–C)
(with very low, rounded epigastric cristae, barely visible postorbital cristae in Phaibulamon, cf. Ng 1992: fig. 1);
broadly triangular median lobe of the posterior margin of the epistome (Fig. 3A–C) (acutely triangular in
Phaibulamon, cf. Ng 1992: fig. 1); proportionately longer third maxilliped ischium (Fig. 7A) (relatively shorter
ischium in Phaibulamon, cf. Ng 1992: fig. 2A); relatively long exopod of third maxilliped extending beyond upper
edge of ischium with long flagellum (Fig. 7A, B) (short exopod just reaching upper edge of ischium, lacking
flagellum in Phaibulamon, cf. Ng 1992: fig. 2A, B); lateral margins of male telson concave (Fig. 4A, D) (lateral
margins of male telson gently convex in Phaibulamon, cf. Ng 1992: fig. 1); G1 relatively more slender, straight,
with a pronounced dorsal flap (Fig. 7C, D) (G1 short, stout, C-shaped, the lower dorsal flap being of a different
shape in Phaibulamon, cf. Ng 1992: fig. 2C–F); and the basal part of the G2 is subquadrate (Fig. 7E) (basal part of
G2 ovate in Phaibulamon, cf. Ng 1992: fig. 2G).
Thampramon gen. nov. most closely resembles species of Thaipotamon Ng & Naiyanetr, 1993 (see Ng &
Naiyanetr 1993) from Thailand in the form of the third maxilliped, male abdomen and G1,. Thaipotamon, however,
is easily separated by a carapace that is prominently and evenly inflated, the chelipeds and ambulatory legs are not
elongated, the distal part of the flap on the terminal segment of the G1 does not have a cleft, and the basal segment
of the G2 is ovate (cf. Ng & Naiyanetr 1993). Most significantly, the anterior male thoracic sternum (notably
somite 4) of Thaipotamon is proportionately more longitudinally elongated, with the sternoabdominal cavity
reaching to just the bases of the coxae of the chelipeds (cf. Ng & Naiyanetr 1993: Figs. 16C, 17C, 20C).
Thampramon gen. nov. resembles species of Tiwaripotamon Bott, 1970, from Indo-China in the form of the
carapace, third maxillipeds, long chelipeds and ambulatory legs, and male abdomen. Tiwaripotamon differs by the
absence of a sulcus on the third maxilliped ischium, the anterior thoracic sternum being longitudinally more
elongated, and most significantly, the G1 being gently curved with the terminal segment subcylindrical, curving
upwards and without a trace of a flap (cf. Ng & Yeo 2001).
The general carapace form, long ambulatory legs, male abdomen and structure of the G1 of Thampramon gen.
nov. are also similar to Nemoron Ng, 1996, described from central Vietnam. The male thoracic sternites 2 and 3 are
completely fused in Nemoron, the third maxilliped ischium lacks a sulcus and the exopod lacks a flagellum (cf. Ng
1996).
Comparative material. Phaibulamon stilipes Ng, 1992: Holotype male (28.5 × 22.7 mm) (ZRC 1992.8325),
Tham Nam Pah Khoan cave, from "K2" resurgence, Kwai Valley, Kanchanaburi Province, Thailand, coll. French
Expedition Kwai 90, 18 August 1990. Nemo
ron nomas Ng, 1996: Holotype male (23.7 × 20.3 mm) (ZRC
1996.94), station Viet 062, Phong Nha, Hang Toi, 35 m above sea level, about 300 m inside cave, Quang Binh
Province, central Vietnam, coll. L. Deharveng, A. Bedos & Levet, 11 January 1995; 1 paratype female (25.4 × 21.3
mm) (ZRC 1996.95), station Viet 067, in forest near Cha Noi, Quang Binh Province, central Vietnam, coll. L.
Deharveng, A. Bedos & Levet, 9 January 1995. Erebusa calobates Yeo & Ng, 1999: Holotype male (20.8 × 17.8
mm) (ZRC 1998.1073), Tham Tê, near Ban Na, Khammouan Province, Laos, coll. L. Deharveng & A. Bedos, 11
February 1998; 2 paratype males (20.0 × 17.4 mm; 19.9 × 17.5 mm), 1 juvenile (ZRC 1998.1074-1075), same data
as holotype; 1 paratype ovigerous female (23.0 × 19.3 mm) (ZRC 1998.1076), Tham Houai Say, near Ban Khen,
Khammouan Province, Laos, coll. F. Brehier, 26 February 1998. Tiwaripotamon edostilus Ng & Yeo, 2001:
Holotype male (36.4 × 28.3 mm) (ZRC 2000.0096), cave at Gia Luang, Cat Ba Island, Ha Long Bay, Vietnam,
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NEW GENUS AND SPECIES OF CRAB FROM THAILAND
coll. L. Deharveng, 28 September 1998; 1 paratype male (40.5 × 31.1 mm) (ZRC 2000.0097), same data as
holotype; 1 paratype male, 1 paratype juvenile (ZRC 2000.0098-0099), cave at Thien Long, Cat Ba Island, Ha
Long Bay, Vietnam, coll. L. Deharveng, 29 September 1998; 1 paratype male (34.3 × 25.6 mm) (ZRC 2000.0100),
Hoa Cuong Cave in Gia Luan, 20°50’20”N 106°58’57”E, Cat Ba Island, Vietnam, coll. M. Kottelat, 25 September
1998; 1 juvenile (ZRC 2000.0101), Sung Sot Cave, Cat Ba island, Ha Long Bay, Vietnam, coll. L. Deharveng, 2
October 1998.
Thampramon tonvuthi sp. nov.
(Figs. 1–7)
Material examined. Holotype: male (39.7 × 31.1 mm) (NIFI CR 00062), Tham Phra Wangdaeng, Baan Chompu
southwest of Thung Salaeng Luang National Park, 400 m from cave entrance, Thailand, coll. C. Vidthayanon &
Pranee Nang-gnam, 29 November 2008. Paratypes: 1 male (26.8 × 21.6 mm) (NIFI), same data as holotype; 1 male
(33.9 × 27.8 mm) (ZRC 2012.1126), same area as holotype, 16.8379°N 100.877°E, cave entrance, coll. C.
Vidthayanon, 8 October 1997; 1 female (45.9 × 35.4 mm) (NIFI CR 00063), same locality as holotype, in twilight
zone, near side entrance of cave, above flowing stream, coll. D. Smart, 27 August 2002; 1 female (42.7 × 36.3 mm)
(ZRC 2012.1127), same locality as holotype, in twilight zone of cave, ca. 100 m from entrance, on wet rock wall, 4
m above stream above bat guano, coll. D. Smart, 28 August 2002.
Diagnosis. As for genus.
Description of male. Carapace wider than long, subquadrate (Figs. 1A, 2A–C). Dorsal surface almost smooth;
regions poorly demarcated; not prominently swollen; H-shaped median groove distinct, deep; cervical grove very
shallow, separating postorbital cristae from short crista that reaches anterolateral margin (Fig. 2A–C). Epigastric
cristae well developed, swollen, surface rugose, not sharp; divided medially by deep Y-shaped groove; postorbital
crista separated from epigastric cristae by shallow groove, relatively sharp, almost smooth (Fig. 2A–C). Frontal
region almost flat (Fig. 3A–C). Frontal margin prominently sinuous, 2 lobes separated by broad, shallow sinus;
outer margin convex, confluent with supraorbital margin (Figs. 2A–C, 3A–C). Supraorbital margin prominently
sinuous, with median part convex, without trace of fissure (Fig. 2A–C). External orbital angle triangular, outer
margin gently serrated, longer than inner margin, tip not projecting beyond level of frontal margin; separated from
anterolateral margin by deep V-shaped cleft (Fig. 2A–C). Epibranchial tooth sharp but relatively short, rest of
anterolateral margin short, gently serrated, gently curving to join posterolateral margin (Fig. 2A–C). Posterolateral
margin distinctly convex, converging strongly to gently convex posterior carapace margin (Fig. 2A–C). Suborbital
margin gently concave, entire, lined with fine granules (Figs. 3A–C). Orbit relatively large, almost completely
filled by large eyes (Figs. 2A–C, 3A–C). Eyestalk elongated; cornea ovate, well developed, completely pigmented,
with small, distal tuft of short setae (Figs. 1A, B, 2A–C, 3A–C). Sub-orbital and pterygostomian regions smooth;
sub-branchial region rugose (Figs. 1B, 3A–C). Epistome subrectangular, relatively narrow longitudinally; posterior
margin with prominent median triangle, lateral margins gently sinuous (Fig. 3A–C). Third maxilliped quadrate;
ischium subrectangular with submedian oblique sulcus; merus quadrate with median part depressed; exopod
slender, reaching to just beyond distal edge of ischium, with well-developed flagellum which just reaches beyond
width of merus (Fig. 7A, B).
Chelipeds elongated (Figs. 1A, B, 2A–C, 5D). Basis-ischium short, inner margin with 5 granules. Merus with
inner margin serrulated, inner distal angle with short spine; outer surface rugose (Figs. 1A, B, 2A–C, 5D). Carpus
with outer surface rugose; inner distal angle with prominent sharp tooth, outer distal margin with small sharp
granules (Figs. 1A, 2A–C, 5D). Chela elongated; relatively slender fingers, slightly longer than palm; outer surface
of palm gently rugose, not granulated; subventral margin of palm with very low longitudinal keel (Fig. 5A–C).
Pollex with distinct low subventral longitudinal keel with adjacent shallow groove; dactylus almost smooth; tips of
fingers corneous; cutting edges each with 2 or 3 broadly triangular teeth and numerous denticles (Fig. 5A–C).
Ambulatory legs conspicuously long; second leg longest, fourth leg shortest (Figs. 1A, B, 2A–C, 6A). Dorsal
margin of merus slightly cristate, varying from uneven to serrulated, subdistal angle visible but not produced to
form spine (Figs. 2A–C, 6A). Carpus elongated with dorsal margin gently serrulated (Fig. 6A). Propodus distinctly
laterally flattened with dorsal and ventral margins serrulated (Fig. 6A). Dactylus long, gently falcated with
proximal part almost straight (Fig. 6A); second and third dactylus longest, first and fourth shortest (Fig. 2A–C).
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FIGURE 1. Thampramon tonvuthi gen. et sp. nov. Holotype male (39.7 × 31.1 mm) (NIFI CR 00062), colour in life. A,
overall dorsal view; B, ventral view; C, in situ in cave.
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NEW GENUS AND SPECIES OF CRAB FROM THAILAND
FIGURE 2. Thampramon tonvuthi gen. et sp. nov. Overall dorsal views. A, holotype male (39.7 × 31.1 mm) (NIFI CR
00062); B, paratype male (33.9 × 27.8 mm) (ZRC 2012.1126); C, paratype female (42.7 × 36.3 mm) (ZRC 2012.1127).
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FIGURE 3. Thampramon tonvuthi gen. et sp. nov. Frontal views of carapace. A, holotype male (39.7 × 31.1 mm) (NIFI
CR 00062); B, paratype male (33.9 × 27.8 mm) (ZRC 2012.1126); C, paratype female (42.7 × 36.3 mm) (ZRC
2012.1127).
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NEW GENUS AND SPECIES OF CRAB FROM THAILAND
FIGURE 4. Thampramon tonvuthi gen. et sp. nov. A–C, paratype male (33.9 × 27.8 mm) (ZRC 2012.1126); D–F,
holotype male (39.7 × 31.1 mm) (NIFI CR 00062). A, D, anterior thoracic sternum, abdominal somite 6 and telson; B, E,
thoracic sternum and abdomen; C, F, posterior thoracic sternum and abdominal somites 1–3.
Thoracic sternum relatively smooth; somites 2, 3 completely fused without trace of sutures, forming wide
triangular plate; sternites 3, 4 fused but with lateral sutures just visible as shallow depressions; sterno-abdominal
cavity reaching to imaginary line joining median parts of cheliped coxae (Fig. 4A, D). Press-button abdominal
locking mechanism peg-like, directed anteriorly, on posterior half of somite 5.
Male abdomen triangular, all somites, telson free (Figs. 1B, 4A–F). Telson as long as broad, with concave
lateral margins (Fig. 4A, D); somites 4–6 progressively longitudinally broader, more trapezoidal in shape (Fig. 4B,
E). Somites 1, 2 wide, reaching across thoracic sternum, completely covering thoracic somite 8; somite 2 with
lateral margins rounded; somite 1 very narrow (Fig. 4C, F).
G1 relatively more slender, almost straight; subterminal segment tapering to neck-like structure; distal segment
short, basal part swollen, curved with open tip, with pronounced dorsal flap, deeply concave anteriorly (Fig. 7C,
D). G2 long, basal part subquadrate, flagellum shorter than basal segment (Fig. 7E)
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FIGURE 5. Thampramon tonvuthi gen. et sp. nov. A, holotype male (39.7 × 31.1 mm) (NIFI CR 00062); C, D, paratype
male (33.9 × 27.8 mm) (ZRC 2012.1126). A, C, outer view of left chela; B, outer view of right chela; D, dorsal view of
left chela.
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NEW GENUS AND SPECIES OF CRAB FROM THAILAND
FIGURE 6. Thampramon tonvuthi gen. et sp. nov. A, paratype male (33.9 × 27.8 mm) (ZRC 2012.1126); B, paratype
female (42.7 × 36.3 mm) (ZRC 2012.1127). A, right fourth ambulatory leg; B, thoracic sternum showing vulvae (v).
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FIGURE 7. Thampramon tonvuthi gen. et sp. nov. Paratype male (33.9 × 27.8 mm) (ZRC 2012.1126). A, left third
maxilliped; B, exopod of left third maxilliped; C, ventral view of left G1; D, dorsal view of left G1; E, left G2. Scales =
2.0 mm.
Females. The gastric and branchial regions of the two female paratypes (Fig. 3C) are slightly more swollen
and convex compared to those of males (Fig. 3A, B). The female abdomen is rounded and completely covers the
thoracic sternum. The vulva is large, occupying almost the entire width of somite 6 along its inner portion, the
opening covered by a weakly chitinised membrane without operculum (Fig. 6B).
Variation. The postorbital crista varies from very sharp in the holotype male and females to low and less
developed in one paratype male (ZRC 2012.1126). The postorbital cristae are slightly sinuous in the two smaller
paratype males (26.8 × 21.6 mm, NIFI; 33.9 × 27.8 mm, ZRC 2012.1126), but are straight in the holotype male and
in the females. These differences can probably be explained by size. The lateral margins of the median triangular
lobe of the posterior margin of the epistome in the largest holotype male are also more crenulated (Fig. 3A) than
those of the smaller males and females (Fig. 3B, C). In the holotype male, the larger chela is stout and inflated (Fig.
5A); in the smaller paratype male (ZRC 2012.1126), this chela is less inflated and the dentition is weaker (Fig. 5C).
The male abdomen varies slightly in shape. It is relatively more triangular in shape in the two smaller male
paratypes (26.8 × 21.6 mm, NIFI; 33.9 × 27.8 mm, ZRC 2012.1126), having the lateral margins of somites 4–6
gently convex to almost straight (Fig. 4B), and the lateral margins of the telson concave (Fig. 4A). In the largest
male specimen (39.7 × 31.1 mm, NIFI CR 00062) (the holotype), the abdomen is broader, mainly because the
lateral margins of somites 4–6 are more prominently convex (Fig. 4E), with the lateral margins of the telson almost
straight (Fig. 4D).
Colour in life. Dorsal carapace orange-brown; chelipeds yellowish-white; ambulatory legs purple-brown on
dorsal surface; ventral surfaces dirty-white to yellow-white (Fig. 1).
Etymology. The name is in honor to Mr. Pituk Tonevuth, a community leader in Thailand who has devoted his
life to protect the limestone areas in the type locality from impacts by rock quarry concessions, and he has now
succeeded in having the entire areas protected as part of the Thung Salaeng Luang National Park.
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NEW GENUS AND SPECIES OF CRAB FROM THAILAND
Ecology. The type locality, Tham Phra karst and Klong Chompu, is in the Nan River subcatchment and part of
the Chao Phraya Basin. The basin includes several limestone caves and their associated subterranean streams. Most
of the area is dry evergreen forest, with patches of limestone vegetation. The area has a large number of endemic
taxa, being the only known habitat of cavefishes like Neolissocheilus subterraneus Vidthayanon & Kottelat, 1993
(Cyprinidae), Schistura deansmarti Vidthayanon & Kottelat, 1993, S. spiesi Vidthayanon & Kottelat, 1993
(Nemacheilidae); a lizard Crytodactylus aurobalteatus Sumontha, Panitwong & Deein, 2010 (Gekkonidae); and an
undescribed species of Macrobrachium (Palaemonidae). Much of the area remains unexplored and the endemic
biodiversity is probably much higher. The area meets the criteria established by the Ramsar Convention
(International Convention on Wetlands of International Importance) as a key conservation site, and will be
proposed as such in the near future.
Thampramon tonvuthi gen. et sp. nov. inhabits cave floors with humid and muddy sand substrates, from just
beyond the cave entrance (rarely) to over 600 m deep. It has also been found climbing on the cave walls. While
Thampramon tonvuthi gen. et sp. nov. has only been obtained from inside caves so far, it does not appear to be a
troglobite (see Holthuis 1986; Guinot 1988). Although it has the long ambulatory legs and chelipeds often observed
in many cavernicolous species, it still possesses well-developed eyes with a fully pigmented cornea and has
relatively bright colours on its carapace and legs. Thampramon tonvuthi gen. et sp. nov. probably also forages in
the surrounding forests at night, as do a number of similar terrestrial and semiterrestrial freshwater crabs
(Gecarcinucidae, Potamidae) and land crabs (Gecarcinidae) associated with cave habitats (Ng 1991; Ng & Sket
1996; Ng & Lee 2012). Two species of gecarcinid land crabs, Discoplax longipes A. Milne-Edwards, 1973 (from
New Caledonia and Guam) and D. gracilipes Ng & Guinot, 2001 (from the Philippines) were found to be common
in the associated karst forests after dark and not obligate cave dwellers as was originally thought (see Ng & Guinot
2008). These karst crabs are thus primarily nocturnal animals that forage during the day inside the dark
environment of caves.
Acknowledgements
The authors thank staff and officers at Thung Salaeng Luang National Park for their kind help. The second author
also thanks the community of Baan Klong Chompu village for assistance in the inventories and surveys of the type
locality. He is also grateful to Mr. Dean Smart, a dedicated and passionate cave researcher, for his initial
information about the crab and for collecting two of the specimens. Helpful comments by Neil Cumberlidge and
Peter Castro are much appreciated.
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... The elongated legs of these two species are probably an adaptation to terrestrial life although it is also useful and more advantageous for foraging and navigation in the dark cave environment ). This is also the case of a number of terrestrial potamids and gecarcinucids (e.g., Thampramon tonvuti Vidthayanon, 2013, andStygothelphusa cranbrooki Ng, 2013) and gecarcinid crabs (e.g., Discoplax gracilipes Guinot, 2001, andD. longipes A. Milne-Edwards, 1867) (see Ng 1996Ng , 2013Ng & Guinot 2001;Ng & Vidthayanon 2013). ...
... This is also the case of a number of terrestrial potamids and gecarcinucids (e.g., Thampramon tonvuti Vidthayanon, 2013, andStygothelphusa cranbrooki Ng, 2013) and gecarcinid crabs (e.g., Discoplax gracilipes Guinot, 2001, andD. longipes A. Milne-Edwards, 1867) (see Ng 1996Ng , 2013Ng & Guinot 2001;Ng & Vidthayanon 2013). ...
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... Globally, 13 families, 33 genera and at least 67 species of stygobiotic brachyuran crabs are reported (Hobbs, 2012). In Thailand 107 species of freshwater crabs are recognized (Naiyanetr, 2007;Naiyanetr and Yeo, 2010;Yeo and Naiyanetr, 2010;Ng and Vidthayanon, 2013;Promdam, et al., 2014Promdam, et al., , 2017Lheknim and Ng, 2016;Buatip et al., 2018;Ng et al., 2018;Takeda et al., 2019), but subterranean species remain poorly understood. The first documented record of a the caves and caving in Thailand website (Ellis, 2020), as well as from local guides. ...
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... Vidthayanon & Kottelat, 2003); a cavernicolous potamid crab Thampramon tonvuthi (cf. Ng & Vidthayanon, 2013); and a lizard Crytodactylusauro balteatus (Gekkonidae) (cf. Sumontha et al., 2010). ...
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The freshwater crabs of the genus Tiwaripotamon Bott, 1970 (Potamidae) are revised and the identities of two poorly known species, T. simulum (Alcock, 1909) and T. araneum (Rathbun, 1905), are clarified after a re-examination of the types. Tiwaripotamon, sensu stricto, is restricted to five species, T. annamense (Balss, 1914); T. araneum (Rathbun, 1905); T. pingguoense Dai and Naiyanetr, 1994; T. xiurenense Dai and Naiyanetr, 1994; and a new species, T. edostilus, from Vietnam. Tiwaripotamon simulum is transferred to the genus Kanpotamon Ng and Naiyanetr, 1993. Keys to the species of Tiwaripotamon and Kanpotamon are also provided.
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ABSTRACT A new genus and species of troglobitic potamid crab is described from central Laos. The new taxon possesses a unique combination of morphological characters not found in any other known fresh-water crabs. Key diagnostic characters include the compressed frontal regions, reduced eyes, auriculiform merus of the third maxilliped, long ambulatory legs, and unusual male first pleopod structure. The reduced eyes and extremely long slender legs make this species the most highly modified cave-dwelling crab reported thus far from Indochina.
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The identity and taxonomy of 21 species of Thai freshwater crabs described between 1869 and 1992 of the families Potamidae (Potamon kanchanaburiense Naiyanetr, 1992; P. maesotense Naiyanetr, 1992; P. boonyaratae (Naiyanetr, 1987); Potamon phuphanense Naiyanetr, 1992; P. erawanense Naiyanetr, 1992; P. maehongsonense Naiyanetr, 1992; P. yotdomense (Naiyanetr, 1984); Dromothelphusa phrae (Naiyanetr, 1984); Larnaudia chaiyaphumi Naiyanetr, 1982; Thaipotamon siamense (A. Milne Edwards, 1869); T. smitinandi (Naiyanetr & Türkay, 1984); Thaiphusa sirikit (Naiyanetr, 1992); Demanietta tritrungense (Naiyanetr, 1986)), Gecarcinucidae (Phricotelphusa ranongi Naiyanetr, 1982; Thaksinthelphusa yongchindaratae (Naiyanetr, 1988)) and Parathelphusidae (Somanniathelphusa bangkokensis Naiyanetr, 1982; S. maehongsonensis Naiyanetr, 1987; S. fangensis Naiyanetr, 1987; S. denchaii Naiyanetr, 1984; S. nani Naiyanetr, 1984; Heterothelphusa beauvoisi (Rathbun, 1902)) are clarified. Four new genera are established (three belonging to the Potamidae: Thaipotamon, Kanpotamon and Thaiphusa; and one to the Gecarcinucidae: Thaksinthelphusa), and 13 new species (11 Potamidae: Potamon lipkei, P. nan, P. namlang, P. jarujini, P. maesariang, Ρ. ubon, P. somchaii, Thaipotamon lomkao, Τ. dansai, Τ. varoonphornae, Kanpotamon duangkhaei; and two Parathelphusidae: Somanniathelphusa phetchaburi, S. chiangmai) described. Detailed descriptions and figures are provided of all the taxa.