PROTEOCEPHALUS BROOKSI N-SP (CESTODA, PROTEOCEPHALIDAE) IN THE NEOTROPICAL FRESH-WATER FISH RHAMDIA-GUATEMALENSIS (SILURIFORMES, PIMELODIDAE) FROM LAKE-CATEMACO, VERACRUZ, MEXICO

Proteocephalus brooksi n. sp. is described from the neotropical pimelo did fish Rhamdia guatemalensis from Lake Catemaco, Veracruz, Mexico. T he new species is characterized by the ''paramuscular'' position of vi tellaria, the cortical origin of uterine stem with development of medu llar lateral branches, the alternated position of vagina (anteriorly a nd posteriorly to citrus sec), and the absence of apical organ and vag inal sphincter. Proteocephalus brooksi most closely resembles Nomimosc olex matogrossensis from which it differs iii a series of characters. The probable paraphyletic nature of both Proteocephalus and Nomimoscol ex and the convergent evolution of the ''paramuscular'' location of vi tellaria among proteocephalideans are suggested, and the need for a ph ylogenetic analysis of the group is emphasized. The new species is ass igned to Proteocephalus pending such an analysis.