Molecular phylogenetic analysis of the genus Gyrodactylus (Platyhelminthes: Monogenea) inferred from rDNA ITS region: subgenera versus species groups
Analyses of small subunit ribosomal RNA gene sequences of representatives of major taxa of Monopisthocotylea were performed to identify the sister group of Gyrodactylus. Nuclear ribosomal DNA sequences 1 from the complete internal transcribed spacer (ITS) region were used to infer phylogeny of 37 Gyrodactylus species and Gyrodactyloides bychowskii, Macrogyrodactylus polypteri and Gyrdicotylus gallieni, using maximum likelihood, parsimony and Bayesian inference. The genus Gyrodactylus appeared to be a monophyletic group in all analyses, based on the present data set. Within the genus, there were 3 major groups recognized by high bootstrap values and posterior probabilities. None of the 6 subgenera appeared to be monophyletic, and the most basal subgenus G. (Gyrodactylus) was paraphyletic. Characteristics of the excretory system of Gyrodactylus do not seem to be conservative enough to reveal subgenera within Gyrodactylus and we suggest abandoning existing subgenera as indicators of phylogeny. The grouping of species based on the morphology of the ventral bar and marginal hooks seems to have sufficient power to infer relationships between the Gyrodactylus species.(Received May 14 2003)
(Revised June 26 2003)
(Accepted June 26 2003)
Key Words: Monogenea; Gyrodactylus; SSU; ITS; phylogeny.
c1 FRS Marine Laboratory, PO Box 101, Victoria Road, Aberdeen AB11 9DB, UK. Tel: +44 1224 295 683. Fax: +44 1224 295 667. E-mail: I.Matejusova@marlab.ac.uk
1 Nucleotide sequence data reported in this paper are available in the GenBank, DDBJ and EMBL databases under the accession numbers AJ566375-79, AJ566768, AJ567670-74, AJ581657.