Taxonomic status of Pelichnibothrium speciosum Monticelli, 1889 (Cestoda: Tetraphyllidea), a mysterious parasite of Alepisaurus ferox Lowe (Teleostei: Alepisauridae) and Prionace glauca (L.) (Euselachii: Carcharinidae)

Abstract

Comparison of freshly collected tetraphyllidean cestodes from a teleost fish, Alepisaurus ferox Lowe, from Japan with types and vouchers of Pelichnibothrium speciosum Monticelli, 1889, described from the same host, and specimens of Prionacestus bipartitus Mete and Euzet, 1996, from the spiral valve of a shark, Prionace glauca (Linnaeus), from the Indian Ocean between Reunion and Madagascar, revealed their conspecificity. Consequently, P. bipartitus is considered a junior synonym of P speciosum and the genus Prionacestus Mete and Euzet, 1996 is suppressed. The life-cycle of the parasite, which retains larval features and is considered to represent a neotenic form, is discussed.