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

A new troglobitic shrimp, Macrobrachium catonium, is described from the Vaca Plateau, Cayo District of Belize. It is the third albinistic member of the genus known to occur along the Gulf of Mexico-Caribbean versant of Middle America. It may be distinguished from the Oxacan M. villalobosi 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 vaulted) rostrum, and from both in that usually there are more than two ventral rostral teeth, and fewer subapical spines on the appendix masculina.