Potamocarcinus H. Milne Edwards, 1853

Magalhães, Célio, Wehrtmann, Ingo S., Lara, Luis Rólier & Mantelatto, Fernando L., 2015, Taxonomy of the freshwater crabs of Costa Rica, with a revision of the genus Ptychophallus Smalley, 1964 (Crustacea: Decapoda: Pseudothelphusidae), Zootaxa 3905 (3), pp. 301-344 : 329

Potamocarcinus H. Milne Edwards, 1853

Potamocarcinus H. Milne Edwards, 1853: 208 .

Type species. Potamocarcinus armatus H. Milne Edwards, 1853 [by monotypy].

Diagnosis (modified from Rodríguez & Hobbs 1989). Third maxilliped exognath between 0.5 to 0.9 times length of endognath ischium. Lateral spines of carapace unusually well developed in some species. G1 straight; marginal process (caudal process, sensu Smalley 1964a) simple, short or sometimes distally projected; cephalic surface with cephalic process (lateral process, sensu Rodríguez & Hobbs 1989) developed (bifid in some species) or rudimentary; mesial process (cephalic process, sensu Rodríguez & Hobbs 1989) subtriangular, usually large, located distally; apex usually elongated mesio-laterally; mesial lobe (marginal lobe, sensu Rodríguez & Hobbs 1989) produced distally in some species; apical field of spines well developed, partly covered by hood derived from produced mesial process.

Distribution. The species of this genus are distributed from southern Mexico to northwestern Colombia. In Costa Rica the genus occurs in both the Atlantic and Pacific drainages.

Remarks. The relationships with other pseudothephusid genera, inferred by G1 morphology, were discussed by Rodriguez (1982) and Rodríguez & Hobbs (1989).