Phylogenetic relationships of fish leeches (Hirudinea, Piscicolidae) based on mitochondrial DNA sequences and morphological data

摘要

Phylogenetic relationships of fish leeches (Piscicolidae) were deduced from combined mitochondrial DNA sequences of 12S rDNA and COI genes using Bayesian inference and Maximum Likelihood, as well as from a combined molecular-morphological data matrix using Maximum Parsimony. Monophyly of the family was confirmed. The traditional subdivision into three subfamilies, the Platybdellinae, Pontobdellinae, and Piscicolinae, received weak support, but was not challenged by alternative groupings. In contrast to prior classifications, a basal split emerged between the Pontobdellinae on the one hand, and the Platybdellinae and Piscicolinae on the other. The complex coelomic system of pontobdellines is viewed as plesiomorphic, and independent reductions of the coelom in other fish leech groups are hypothesized. According to the inferred phylogeny, seawater was the primary habitat of fish leeches. Eurasian freshwaters were colonized by a species-rich freshwater clade (genera Piscicola, Baicalobdella, Cystobranchus and Caspiobdella) and, probably independently, by the Asian genus Limnotrachelobdella.