PROTEOCEPHALUS JOANAE SP-N (EUCESTODA, PROTEOCEPHALIDEA), A PARASITE OF XENODON NEUWIEDI (SERPENTES, COLUBRIDAE) FROM SOUTH-AMERICA

A new species of Proteocephalus, P. joanae sp. n., is described from t he intestine of the colubrid snake, Xenodon neuwiedi (Gunther, 1863) ( Serpentes: Xenodontinae), from Brazil. The new species differs from al l other members of Proteocephalus by possessing a swollen elongated po sterior part of the scolex herein considered as a metascolex. Furtherm ore, it is the only member of New World Proteocephalus possessing a vo luminous glandular apical organ larger than suckers. P. joanae is also characterized by very elongated gravid proglottides. This is the firs t member of the Proteocephalidea occurring in Xenodon. Even though the species differs significantly from other species of the genus Proteoc ephalus, which currently contains many species that are morphologicall y very distinctive, it seems prudent to refrain from reworking the cla ssification of the group until accurate redescriptions of Neotropical species can be conducted, preferably based on examination of type and freshly collected material. The definition of the metascolex is discus sed herein.