Key to Indo-West Pacific genera of the Porcellanidae
1. Antennal peduncle with movable (second to fourth) articles freely accessible to orbit .............................. 2
- Antennal peduncle with movable articles excluded from orbit by projection of immovable (first) article meeting anterior margin of carapace ........................................................................................................... 6
2. Chelipeds flattened. Pterygostomian flap entire .......................................................................................... 3
- Chelipeds robust. Posterior part of pterygostomian flap composed of 1 or more pieces separated by mem- branous interspaces from anterior part ............................................................ Pachycheles Stimpson, 1858
3. Rostrum narrow, triangular, with row of spines on each lateral margin. Telson composed of 5 plates ........ ................................................................................................................................ Petrocheles Miers, 1876
- Rostrum broad, unarmed except for sometimes with supraocular spine on each lateral margin. Telson composed of 7 plates ................................................................................................................................... 4
4. Carapace with gastric region strongly elevated. Ambulatory legs subcylindrical......................................... ..................................................................................................................... Neopetrolisthes Miyake, 1937a
- Carapace flattish or somewhat convex on dorsal surface. Ambulatory legs flattish ................................... 5
5. Carapace uneven on dorsal surface. Median lobe of rostrum with pair of lateral elevations........................ ........................................................................................................................... Novorostrum Osawa, 1998a
- Carapace genarally even on dorsal surface. Median lobe of rostrum without lateral elevations .................. .......................................................................................................................... Petrolisthes Stimpson, 1858
6. Carapace broader than long ......................................................................................................................... 7
- Carapace as long as or longer than broad .................................................................................................. 11
7. Ambulatory legs with dactyli each terminating in simple claw (no corneous spines present on flexor mar- gin) .................................................................................................................... Raphidopus Stimpson, 1858
- Ambulatory legs with dactyli each with biunguiculate claw....................................................................... 8
8. Branchial margins of carapace armed with spines, outer orbital angle terminating in small spine............... ................................................................................................... Aliaporcellana Nakasone & Miyake, 1969
- Branchial margins of carapace without spines, outer orbital angle unarmed .............................................. 9
9. Carapace with pair of transverse ridges along cervical regions. Telson composed of 5 plates ..................... ........................................................................................................................ Heteropolyonyx Osawa, 2001
- Carapace with weak or distinct, cervical grooves. Telson composed of 7 plates ...................................... 10
10. Carapace with dorsal regions well defined by grooves; cervical and gastric grooves formed by thinning and gradual decalcification of cuticle ........................................................Eulenaios Ng & Nakasone, 1993
- Carapace with dorsal regions not distinctly defined by grooves .......................... Polyonyx Stimpson, 1858
11. Carapace distinctly elongate. Dactyli of ambulatory legs triunguiculate or quadriunguiculate................ 12
- Carapace not elongate. Dactyli of ambulatory legs each terminating in a single claw ............................. 13
12. Carpi of chelipeds longer than broad. Dactyli of ambulatory legs quadriunguiculate .................................. ............................................................................................................................. Porcellanella White, 1852
- Carpi of chelipeds broader than long. Dactyli of ambulatory legs triunguiculate......................................... .................................................................................................... Pseudoporcellanella Sankarankutty, 1961
13. Carapace strongly areolate on dorsal surface ............................................................................................ 14
- Carapace nearly smooth or striate on dorsal surface ................................................................................. 15
14. Branchial margins of carapace with spines. Chelae flattened ........................... Enosteoides Johnson, 1970
- Branchial margins of carapace without spines. Chelae inflated ..................... Capilliporcellana Haig, 1978
15. Chelipeds subequal, dactyulus of smaller cheliped not twisted .......................... Porcellana Lamarck, 1801
- Chelipeds unequal, dactylus of smaller cheliped usually twisted.............................................................. 16
16. Carapace with dorsal regions clearly defined. Rostrum broadly triangular or rounded in dorsal view, median lobe strongly deflexed ............................................................................... Ancylocheles Haig, 1978
- Carapace with dorsal regions weakly defined. Rostrum horizontal, tridentate or trilobate in dorsal view [except for Pisidia dispar (Stimpson, 1858) with rostrum strongly bent ventrally, broadly rounded in dor- sal view]..................................................................................................................................................... 17
17. Chelae rather flattish, showing pronounced sexual dimorphism in spinulation as well as in degree of dis- tortion of fingers ............................................................................................................ Pisidia Leach, 1820
- Chelae subcylindrical, generally similar in both sexes ...................................... Lissoporcellana Haig, 1978