112 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.24 



Petrolisthes ortmanni Nobili 

 Plate 23, fig. 3 



Petrolisthes ortmanni Nobili, 1901b, p. 16 (type locality, Bahia de 

 Santa Elena, Ecuador). Rathbun, 1910, p. 599. Haig, 1957b, 

 p. 6. 



Petrolisthes sp., Nobili, 1901b, p. 16. Rathbun, 1910, p. 599. 



Previous records: 

 Panama. Isla Flamenco: E. Festa (Nobili). 

 Colombia. Isla Gorgona: Askoy (Haig). 

 Ecuador. Bahia de Santa Elena: E. Festa (Nobili). 



Diagnosis: Carapace nearly smooth, anterior regions and grooves 

 strongly accentuated ; no epibranchial spine ; front trilobate ; carpus less 

 than one and a half times as long as wide, naked or sparsely hairy, 

 proximal half of anterior margin with three broad teeth, occasionally 

 somewhat coalesced; manus not swollen, without a heavy crest on outer 

 margin ; merus of walking legs unarmed. 



Description: Carapace nearly smooth, but with distinct plications 

 on lateral margins and on protogastric and hepatic regions. Protogas- 

 tric and hepatic lobes, and the grooves defining them, strongly ac- 

 centuated. Frontal region strongly deflexed ; front trilobate, median 

 lobe projecting only slightly beyond lateral lobes. Outer orbital angle 

 only very slightly produced. No epibranchial spine. Entire carapace 

 nearly glabrous, only a slight trace of hairs on frontal region. 



First and second movable segments of antenna roughened by gran- 

 ules ; third nearly smooth ; flagellum variable, usually naked but occa- 

 sionally with long or vestigial hairs. Outer maxillipeds faintly rugose. 



Merus of chelipeds nearly smooth, armed on anterior margin with 

 a finely granular lobe. Carpus less than one and a half times as long 

 as wide, anterior margin with three broad teeth, distal one usually 

 smallest, these teeth confined to proximal half of margin and occasion- 

 ally somewhat coalesced; surface covered with flattened granules; a me- 

 dian longitudinal crest, obsolescent in some specimens ; granules raised 

 and obliquely elongated to form a low crest along posterior margin. 

 Manus finely granular, not swollen, its outer margin thin ; granules 

 rather rough and projecting in occasional specimens. Fingers granular as 

 in manus ; gape with a short, thick pubescence. Chelipeds with a trace 

 of fine hairs in some specimens. 



Walking legs smooth or punctate, all segments with long scattered 

 setae. Merus unarmed, that of leg 3 slightly inflated. 



