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| Arachnothelphusa sarang Grinang & Ng, 2021 Raffles Bulletin of Zoology. 69 Photographs: Tan Heok Hui. |
Abstract
A new species of cavernicolous gecarcinucid crab, Arachnothelphusa sarang, is described from a limestone cave in northern Sarawak, Malaysian Borneo. This increases the number of Arachnothelphusa species to six. It is the second member in the genus that is known to primarily occupy limestone caves, the other being A. rhadamanthysi Ng & Goh, 1987, from Gomantong in Sabah. Both species appear to be cavernicolous species with pale body colouration in life.
Key words: Brachyura, taxonomy, Oriental region, freshwater crab, cavernicolous crab
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| Fig. 1. Arachnothelphusa sarang, new species. A, male (12.1 × 9.9 mm) (ZRC 2020.0351), Batu Rusa cave, Bukit Sarang, Bintulu, Sarawak, Malaysia; B, female (12.9 × 10.4 mm) (ZRC 2020.0351), Batu Kelelut, Bukit Sarang, Bintulu, Sarawak, Malaysia, specimen; C–E, paratype male (18.7 × 15.3 mm) (ZRC 2020.0099), Bukit Sarang, Bintulu, Sarawak, Malaysia; F, paratype female (15.8 × 11.8 mm) (ZRC 2020.0099), Bukit Sarang, Bintulu, Sarawak, Malaysia. A, B, photographed in situ; C, F, overall dorsal habitus; D, ventral view of cephalothorax; E, frontal view of cephalothorax and chelae. Photographs: Tan Heok Hui. |
TAXONOMY
Family Gecarcinucidae Rathbun, 1904
Arachnothelphusa Ng, 1991
Type species. Potamon (Potamon) melanippe De Man, 1899,
by original designation.
Arachnothelphusa sarang, new species
Diagnosis. Carapace surface convex, rugose, finely
granular; anterolateral margins convex, serrated; antero- and
posterolateral regions prominently rugose, covered with
numerous coarse granules; epibranchial tooth very low or
indistinct; external orbital tooth very low, broadly triangular,
outer margin slightly concave, distinctly serrated; epigastric
and postorbital cristae distinct; cervical and H-grooves deep,
not confluent (Fig. 2A, C); ambulatory legs long, merus of
fourth ambulatory legs subequal to length of carapace (Fig.
2A, B, E); carpus of chelipeds rugose, with fine granules,
inner angle with broadly triangular tooth (Fig. 2A, D); chela
relatively short, fingers as long as palm, cutting teeth on
pollex not prominent (Fig. 2D). Male pleon T-shaped, somite
6 subequal to length of telson (Fig. 2B). G1 slender, sinuous,
gently curving outwards; terminal segment cylindrical,
tapering, about one third length of subterminal segment (Fig.
3A–D). G2 with short distal segment, less than a quarter
length of basal segment (Fig. 3E).
Etymology. The species is named after the locality where
the holotype was collected. The name is used as a noun in
apposition.
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| Fig. 6. Live colours of Arachnothelphusa rhadamanthysi from Gomantong limestone cave in Sabah, specimen not collected. A, male, from outside of the cave; B, inside of cave. Photographs: Keith Christenson. |
Jongkar Grinang and Peter K. L. Ng. 2021. A New Species of the Genus Arachnothelphusa Ng, 1991 (Crustacea: Decapoda: Gecarcinucidae) from A Limestone Cave in Sarawak (Malaysian Borneo). Raffles Bulletin of Zoology. 69; 1–7.
