Arachnothelphusa Ng 1991
Creators: name: Grinang, Jongkar
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Gecarcinucidae
Arachnothelphusa

description: Key to species of Arachnothelphusa of Borneo   
 1. Epibranchial tooth very low or indistinct; external orbital tooth very low, broad; anterolateral region less rugose, fine granules, carapace surface smooth (Figs. 1C, F, 2A, B, C, F, G, 4A); G1 gently curving outwards, terminal segment about one-third length of subterminal segment; distal segment of G2 less than a quarter length of basal segment (Fig. 3A–E)................................................... A. sarang, new species (northern Sarawak)   
– Epibranchial tooth distinct, triangular; external orbital tooth triangular; anterolateral region prominently rugose, coarse granules, carapace surface rugose (Fig. 4B–E); G1 gently or strongly curving outwards, terminal segment either half, onethird or a quarter length of subterminal segment; distal segment of G2 either a quarter or one-fifth length of basal segment (Fig. 5)..............................................................................................2  
2. Epibranchial tooth distinct, acutely triangular; G1 strongly curving outwards (Fig. 5F, H, O, Q)......................................3  
– Epibranchial tooth distinct, relatively blunt; G1 gently curving outwards (Fig. 5A, C, K)........................................................4  
 3. Epibranchial tooth acutely triangular, distinctly separated from external orbital tooth by wide, deep cleft; external orbital acutely triangular (Fig. 4B); terminal segment of G1 about half of length of subterminal segment; distal segment of G2 about quarter length of basal segment (Fig. 5A–E)....................................................... A. merarapensis (northern Sarawak)   
 – Epibranchial tooth distinct but relatively small, separated from external orbital tooth by small cleft; external orbital tooth broadly triangular (Fig. 4E); terminal segment of G1 about one-third of length of subterminal segment; distal segment less than a quarter length of basal segment (Fig. 5O–S).................................................. A. melanippe (central Kalimantan)   
 4. Epibranchial tooth distinct; external orbital tooth broadly triangular (Fig. 4D); terminal segment of G1 about a third length of subterminal segment (Fig. 5K–M)........................................................................ A. kadamaiana (northern Sabah)   
– Epibranchial tooth distinct; external orbital tooth triangular; terminal segment of G1 about a quarter length of subterminal segment....................................................................................5  
 5. Epibranchial tooth distinct on both sides, separated from external orbital tooth by deep, broad U-shaped cleft; external orbital tooth triangular (Fig. 4C); G1 with cone-shaped terminal segment, about a quarter length of subterminal; distal segment of G2 less than fifth length of basal segment (Fig. 5F–J)............................................................ A. terrapes (eastern Sabah)   
 – Epibranchial tooth distinct on both sides, small, blunt, not separated from external orbital tooth by cleft.................................................................... A. rhadamanthysi (eastern Sabah)
description: Published as part of Grinang, Jongkar & Ng, Peter K. L., 2021, A new species of the genus Arachnothelphusa Ng, 1991 (Crustacea: Decapoda: Gecarcinucidae) from a limestone cave in Sarawak (Malaysian Borneo), pp. 1-7 in Raffles Bulletin of Zoology 69 on page 6, DOI: 10.26107/RBZ-2021-0001, http://zenodo.org/record/5351566