An assessment of the phylogeny of the Branchiobdellida (Annelida: Clitellata), using PAUP

Abstract

Analyses using PAUP (phylogenetic analysis using parsimony) were conducted on a matrix of 24 taxa and 26 characters. The taxa included generalised descriptions of a haplotaxid and a lumbriculid oligochaete as outgroups with a hypothetical branchiobdellidan ancestor and 21 genera as ingroups. The branchiobdellidan taxon is a monophyly, and using anatomical characters only, is composed of three suprageneric assemblages. The taxonomic rank of the taxon and assemblages cannot be determined until they have been compared with cladistic analyses on other closely related clitellate groups. In the meantime the currently accepted ordinal rank of Branchiobdellida and the major branchiobdellidan families should continue to be used, with the latter reflecting the assemblages of the genera in our analyses: Branchiobdellidae (including Holtodrilus n.gen., Sinodrilus n.gen., and Xironodrilus), Bdellodrilidae (including Caridinophila and Hidejiodrilus n.gen.), and Cambarincolidae. An analysis with two zoogeographical characters in the matrix caused the genera to be divided into their respective North American and Eurasian groups; however, the North American Triannulata appeared constantly in the latter group. The genera in the Branchiobdellidae, as defined by us, are found in both geographical regions, and predictably the assemblage was split in two.