MACROBRACHIUM-CATONIUM, A NEW TROGLOBITIC SHRIMP FROM THE CAYO DISTRICT OF BELIZE (CRUSTACEA, DECAPODA, PALAEMONIDAE)

A new troglobitic shrimp, Macrobrachium catonium, is described from th e Vaca Plateau, Cayo District of Belize. It is the third albinistic me mber of the genus known to occur along the Gulf of Mexico-Caribbean ve rsant of Middle America. It may be distinguished from the Oxacan M. vi llalobosi Hobbs by the eye which is more pigmented and lacks an apical cleft, and by the shorter, often slightly upturned rostrum which does not reach the distal extremity of the antennal scale. It differs from the Tabascan M. acherontium in possessing a more attenuate (less vaul ted) rostrum, and from both in that usually there are more than two ve ntral rostral teeth, and fewer subapical spines on the appendix mascul ina.