A test of monophyly of the gutless Phallodrilinae (Oligochaeta, Tubificidae) and the use of a 573‐bp region of the mitochondrial cytochrome oxidase I gene in analysis of annelid phylogeny

A 573‐bp region of the mitochondrial gene cytochrome c oxidase subunit I (COI) of two species of Inanidrilus Erséus and four species of Olavius Erséus (Phallodrilinae, Tubificidae) is used in a parsimony analysis together with a selection of 35 other annelids (including members of Polychaeta, Pogonophora, Aphanoneura, and the clitellate taxa Tubificidae, Enchytraeidae, Naididae, Lumbriculidae, Haplotaxidae, Lumbricidae, Criodrilidae, Branchiobdellida and Hirudinea), and with two molluscs as outgroups. The data support the monophyly of the Olavius and Inanidrilus group, with a monophyletic Inanidrilus. However, parsimony jackknife analyses show that most of the other groups are unsupported by the data set, thus revealing a large amount of homoplasy in the selected gene region. Practically no information is given of within/between family relationships except for a few, closely related species. This suggests that the analysed COI region is not useful, when used alone, for inferring higher level relationships among the annelids.