A PARAPHYLY OF THE GENUS BOTHRIOCEPHALUS RUDOLPHI, 1808 (CESTODA: PSEUDOPHYLLIDEA) INFERRED FROM INTERNAL TRANSCRIBED SPACER–2 AND 18S RIBOSOMAL DNA SEQUENCES

Phylogenetic relationships between Bothriocephalus species from freshwater and marine teleosts from different geographical regions were studied using internal transcribed spacer–2 and partial 18S ribosomal DNA. The analyses revealed a paraphyly of Bothriocephalus with respect to the genera Polyonchobothrium, Anantrum, and Clestobothrium. The freshwater species Bothriocephalus claviceps, B. acheilognathi, and Bothriocephalus sp. from Dorosoma petenense formed a well-supported monophyletic cluster, with Polyonchobothrium at its base. In contrast, the type species, B. scorpii, clustered within a distinct lineage formed by a heterogeneous assemblage of marine species, Clestobothrium crassiceps and Anantrum tortum, and the freshwater species B. cf. japonicus. This shows that the current morphology-based classification is unlikely to reflect the phylogenetic relationships within this group and will require a thorough revision.