NEW DESCRIPTION OF PROTEOCEPHALUS-PARAGUAYENSIS (RUDIN, 1917) (CESTODA, PROTEOCEPHALIDAE), PARASITE OF HYDRODYNASTES-GIGAS (DUM, BEBR AND DUM 1854) IN PARAGUAY

Proteocephalus paraguayensis, considered by Freze (1965) as a species inquirenda, is redescribed and figured. When compared with other members of the Proteocephalidea, the species shows the following morpho-anatomical characters: the vitelline follicles in a dorsal position, attached to the internal longitudinal musculature and extending into both the cortex and medulla; a characteristic formation of the uterus; the uterine stem in a cortical position and uterine branches in a medullary position; a proximal vaginal sphincter; a very elongate cirrus; and very large Mehlis' glands. The specific status of Proteocephalus paraguayensis is confirmed. Our specimens were taken from Hydrodynastes gigas (the host according to Rudin was "Coluber sp."). Even though the species differs significantly from other proteocephalideans, its systematic and phylogenetic position is not yet clearly demonstrated, and it is decided to refrain from attributing it to a new genus. © 1990 Kluwer Academic Publishers.