PHYLOGENETIC ANALYSIS OF THE MONOGENEA AND THEIR RELATIONSHIPS WITH DIGENEA AND EUCESTODA INFERRED FROM 28S RDNA SEQUENCES

Platyhelminth phylogeny is controversial. Phylogenetic analyses of the partial domain C1 and the full domains D1 and C2 (358 nucleotides) fr om the 28S ribosomal RNA gene for 21 species from the Monogenea, Digen ez, Cestoda, and, as the outgroup, Tricladida reveal major departures from prevailing theory. The Digenea and not the Monogenea (Monopisthoc otylea and Polyopisthocotylea) form the sister group of the cestodes; the Monopisthocotylea and Polyopisthocotylea are each monophyletic, bu t the Monogenea do not form a monophylum; the sister group of the Dige nea + Cestoda is the Polyopisthocotylea; and Monopisthocotylea are the sister group of all other parasitic flatworms. (C) 1997 Elsevier Scie nce B.V.