Redescription of the mole crab Emerita portoricensis Schmitt, 1935 (Crustacea: Decapoda: Hippidae), based on Caribbean populations from Puerto Rico, Belize, Costa Rica, and Panama.

The mole crab Emerita portoricensis Schmitt, 1935 was originally described solely on the basis of few key characters that were not precisely defined, giving reason to question subsequent reports of its distribution. The present study, prompted by recent collections documenting coloration in life, undertakes a comprehensive redescription of the species based on specimens of varied sizes from Puerto Rico, Belize, Costa Rica, and Panama. Collections from the northern Caribbean that at first take appear to represent a northernmost record of E. brasiliensis Schmitt, 1935 or southernmost occurrence of E. talpoida (Say, 1817), may be assignable E. portoricensis as now recognized. Among western Atlantic species, E. portoricensis and E. benedicti have to date been considered to have the dactylus of the first pereopod terminally subacute or sharply pointed, which purportedly separates them from E. brasiliensis and E. talpoida, western Atlantic species in which this article is terminally rounded. However, in E. portoricensis this character varies with specimen size and the magnification at which the distal extreme of the dactylus is examined, being rounded to varying degrees in all but the largest specimens. Even in sexually mature specimens of less than maximum size, this rounded tip is armed by a minute corneous spine in E. portoricensis, although it is less prominent than the terminal spine on the consistently more acute dactylus of E. benedicti at all adult sizes. Also, the carapace color in live specimens of E. portoricensis, as documented for specimens collected in both Belize and Panama, differs from that of E. brasiliensis, E. talpoida, and E. benedicti by typically including longitudinal and diagonal dark bars of olive brown on the branchial regions and a light longitudinal bar marking the posterior quarter of the median line. Posterior to the cervical groove, fine rugae of the carapace that form broken transverse lines are at most little diminished across the mid-dorsal longitudinal line in E. portoricensis and E. benedicti, somewhat more broken in E. brasiliensis, and distinctly diminished to all but absent at the midline in E. talpoida. Previously reported BINs in the Barcode of Life database include sequenced specimens from Costa Rica herein accepted as E. portoricensis. We exclude populations from Brazil that have been mis-assigned to E. portoricensis.