Gordonopsis, Guinot & Richer de Forges, 1995

Ng, Peter K. L. & Forges, Bertrand Richer de, 2020, A revision of the deep-sea porter crabs of the genus Gordonopsis Guinot & Richer de Forges, 1995 (Crustacea, Decapoda, Brachyura, Homolidae), with descriptions of five new species, Raffles Bulletin of Zoology 68, pp. 267-307 : 305

Key to species of Gordonopsis

1. Carapace and pereiopods covered with long dense setae which obscures surfaces and margins ( Fig. 27 A–C); distal edge of dorsal margin of cheliped merus with 1 spine ( Fig. 28E, G, H) ..... Gordonopsis velutina , new species (Admiralty Islands)

– Carapace and pereiopods glabrous, covered with short setae that may obscure surface or longer sparser setae that does not obscure surface (e.g., Figs. 2 A–C, 14A–C, 17A–C); distal edge of dorsal margin of cheliped merus with 2 spines (e.g., Figs. 3F, G, 15G) .............................................................................2

2. Latero-posterior margin of carapace with distinct tubercle or spine (e.g., Fig. 2A); outer margin of P2–P4 coxae unarmed, smooth .....................................................................................3

– Latero-posterior margin of carapace with very low tubercle, barely visible (e.g., Fig. 17A); outer margin of P2–P4 coxae with a spine or tubercle (may be reduced or absent on some of articles) (e.g., Figs. 18J, K, 22I, J) ....................................5

3. Carapace relatively narrower with lateral margins straighter, less convex ( Fig. 9B); carpus of cheliped with 1 spine on each of outer and inner margins, dorsal ridge smooth, unarmed ( Fig. 10F, G) ......... Gordonopsis alaini , new species ( Madagascar)

– Carapace longitudinally ovate, with posterior part more globose, lateral margins distinctly convex (e.g., Fig. 2A); carpus of cheliped with 3 or more spines and spinules on each of outer and inner margins, dorsal ridge not armed with spines or spinules (e.g., Fig. 3F, G) .......................................................4

4. Ambulatory legs long ( Figs. 2A, 6A); distal part of P5 merus extending beyond gastric groove when folded anteriorly ( Figs. 4A, 8A); dorsal ridge of carpus of cheliped with row of low granules ( Figs. 3F, G, 7G); tip of G1 subtruncate ( Figs. 4H, 8K) ... Gordonopsis profundarum ( Alcock & Anderson, 1899) (western Indian Ocean)

– Ambulatory legs short ( Fig. 12A, B); distal part of P5 merus just reaching gastric groove when folded anteriorly ( Fig. 12D); dorsal ridge of carpus of cheliped with row of low sharp tubercles ( Fig. 13F); tip of G1 appears bifurcated ( Fig. 13K) ... Gordonopsis robusta Ng, Padate & Saravanane, 2019 (Andaman Sea)

5. Supraorbital margin proportionately wider, pseudorostral spines relatively short, directed slightly obliquely laterally at angle of 20–30° ( Figs. 14B, 15D, 17B)................................................6

– Supraorbital margin C-shaped, less wide, pseudorostral spines long, directed almost 45° obliquely laterally ( Figs. 21B, 24B) .........................................................................................7

6. Carapace appears inflated when viewed laterally and frontally ( Fig. 15A, B); P2–P4, particularly merus, proportionately shorter ( Fig. 16 E–G, K, L); outer surface of P4 merus with 1 tubercle on proximal part ( Fig. 16G, I)............... Gordonopsis pacifica Takeda & Suyama, 2019 (southern Japan)

– Carapace appears inflated when viewed laterally and frontally ( Fig. 18A, B); P2–P4, particularly merus, proportionately longer ( Fig. 19 D–F); outer surface of P4 merus unarmed, completely smooth ( Fig. 19F)...... Gordonopsis hera , new species ( Papua New Guinea)

7. Outer margin of each P3 and P4 coxa with 2 long spines each ( Figs. 22I, J, 23B, H); outer surface of P4 merus with 1 perpendicular spine on proximal part... Gordonopsis phorcys , new species ( Solomon Islands)

– Outer margin of each P3 and P4 coxa with 1 spine each ( Fig. 26 B–D); outer surface of P4 merus unarmed, completely smooth ..... Gordonopsis ceto , new species (South China Sea)