Arachnothelphusa sarang • A New Species of the Genus Arachnothelphusa Ng, 1991 (Decapoda: Gecarcinucidae) from A Limestone Cave in Sarawak (Malaysian Borneo)
Autors
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.
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.
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.
TAXONOMY
Family Gecarcinucidae Rathbun, 1904
Genus Arachnothelphusa Ng, 1991
Type species Potamon (Potamon) melanippe De Man, 1899, by original designation.
Species 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).
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
Etymology
The species is named after the locality where the holotype was collected. The name is used as a noun in apposition.