Morphological and molecular analyses of the genera Peltidocotyle Diesing 1850 and Othinoscolex Woodland 1933, and a morphological study of Woodlandiella Freze, 1965 (Eucestoda, Proteocephalidea), parasites of South American siluriform fishes (Pimelodidae)

Morphological studies of type-species of the genera Peltidocotyle Diesing, 1850 and Othinoscolex Woodland, 1933 showed that these genera are synonyms. We therefore redescribe the type and fresh material of Peltidocotyle rugos a Diesing, 1850 and P. lenha (Woodland, 1933) [= Othinoscolex lenha Woodlan d, 1933], which appears to constitute two distinct species. They differ in the number and number of layers of testes, the diameter of the metascolex a nd the field occupied by the vitelline follicles. Phylogenetic analyses bas ed on partial DNA sequences of 16S rDNA, 5.8S-ITS2 and 28S rDNA support the se results. P. lenha and Woodlandiella myzofer (Woodland, 1933) are conside red conspecific following a thorough morphological examination. With regard to host-parasite relationships, P. lenha has been reported from two host s pecies, which is unusual as South American proteocephalideans generally dis play an oioxenous type of host-specificity.