Key to the presently known species of Athanopsis Coutière, 1897

Note: previously published keys to Athanopsis (Banner & Banner 1981; Berggren 1991) contain errors due to imperfections in the original descriptions and illustrations of A. australis and A. brevirostris (see Anker & Ahyong 2007; present study)

1a. Merus of third to fifth pereiopods with one to three stout spiniform seta(e)........................................ 2

1b. Merus of third to fifth pereiopods without stout spiniform setae................................................ 4

2a. Orbital teeth reduced; stylocerite overreaching distal margin of second article of antennular peduncle; colour pattern consisting of relatively narrow red transversal bands (two on carapace flanks, four on abdomen) and some pale-yellow transversal bands [southwestern Indian Ocean].................................................... A. rubricinctuta Berggren, 1991

2b. Orbital teeth well developed; stylocerite not reaching distal margin of second article of antennular peduncle; colour pattern consisting of large dorsal red patch on carapace.............................................................. 3

3a. Eyes completely covered in dorsal view; stylocerite blunt distally; merus of third pereiopod ending in blunt angle distoventrally [temperate southern Australia]........................................... A. australis Banner & Banner, 1982

3b. Eyes partly exposed in dorsal view; stylocerite subacute distally; merus of third pereiopod with small acute tooth distoventrally [southern Japan].................................................................... A. dentipes Miya, 1980

4a. Stylocerite not reaching distal margin of second article of antennular peduncle..................................... 5

4b. Stylocerite exceeding distal margin of second article of antennular peduncle...................................... 6

5a. Stylocerite reaching to about mid-length of second article of antennular peduncle; major cheliped fingers with broad hiatus between a few large teeth; carapace not distinctly inflated dorsally; colour pattern consisting of red transversal bands on carapace and abdomen [northwestern Indian Ocean].................................... A. platyrhynchus Coutière, 1897

5b. Stylocerite almost reaching distal margin of second article of antennular peduncle; major cheliped fingers with more numerous, regular teeth; carapace conspicuously swollen dorsally; colour pattern consisting of white carapace and tail fan contrasting with mostly red abdomen [southern Japan to Indonesia]......................................... .. A. gotoi sp. nov.

6a. Rostrum subtriangular, as broad as long, not reaching distal margin of first article of antennular peduncle; second article of antennular peduncle wider than long; major cheliped with dense setal brush on pollex and a few setae on adjacent portion of palm; colour pattern consisting of broad red transversal bands on abdomen and mostly reddish carapace flanks [Red Sea, Madagascar, southern Japan].................................................. A. brevirostris Banner & Banner, 1981

6b. Rostrum more elongate, longer than broad, reaching well beyond distal margin of first article of antennular peduncle; second article of antennular peduncle as wide as long; major cheliped with dense setal brush on pollex extending to adjacent portion of palm; colour pattern consisting of broad red transversal bands on abdomen and mostly white carapace, with a few red patches [northeastern Australia]............................................................... A. saurus Anker, 2011