DECAPOD CRUSTACEANS OF THE WEST INDIES 79 



Remarks. — This small shrimp superficially resembles juvenile 

 specimens of Atya, but it can readily be distinguished by the elongate 

 carpus of the second pereiopod. 



As Potimirim glabra is the only species of the genus collected on 

 Dominica during the present survey and as it was found in the Lau- 

 rent River, a tributary of the Layou from which came the two ovig- 

 erous females questionably identified by Pocock (1889) as Caridina 

 americana, it seems likely that the latter specimens may belong to 

 this species. 



AU of the specimens of P. glabra in the present collections were 

 taken in February and March; the single ovigerous female was found 

 in the latter month. 



13. Potimirim mexicana (De Saussure) 



Figure 19d 



Caridina mexicana De Saussure, 1857c, p. 505 [type-locality: Veracruz, Mexico]. 



Atyoida Mexicana. — Von Martens, 1868, p. 49. 



Ortmannia potimirim. — Rathbun, 1901, p. 120 [not Atyoida potimirim Mliller, 



1881, p. 117]. 

 Ortmannia mexicana. — Bouvier, 1904, p. 136; 1925 [part], p. 284, figs. 660-667. 

 Potimirim mexicana. — Holthuis, 1954 [part], p. 4. — Villalobos, 1960, p. 295, pis. 



6-9. 



Diagnosis. — Orbital margin unarmed. Rostrum without dorsal 

 teeth, dorsal margin nearly straight, ventral margin dentate but 

 not finely serrate. Ventral margins of abdominal pleura unarmed. 

 Eyes not reduced. Basal segment of antennular peduncle without 

 dorsal spines proximal to series bordering distal margin. Pereiopods 

 without exopods. Fingers of chelae of first and second pereiopods 

 bearing terminal tufts of long hair. Carpus of second pereiopod much 

 longer than broad. Last three pereiopods without prominent horny 

 scales or tubercles. Merus of third pereiopod not noticeably broader 

 than that of fourth. Appendix masculina on second pleopod of male 

 without deep, unarmed sinus in sinuous posterior margin. A small 

 species, maximum postorbital carapace length about 6 mm. 



Habitat. — Freshwater streams. 



Distribution. — Northeastern Mexico to Republic of Costa Rica, 

 Cuba, Jamaica, Puerto Rico. 



Remarks. — In view of the discovery on Dominica of Potimirim 

 glabra, a species known previously from the mainland of Central and 

 South America, West Indian material identified as P. mexicana 

 should be examined carefully to be sure that the closely related 

 P. potimirim (Miiller, 1881) is not represented. The latter species, 

 thus far recorded only from South America, may be distinguished, 

 according to Villalobos (1960), by the narrower appendix masculina 

 on the second pleopod of the male. 



