Phylogeny and biogeography of the Ergasilidae (Copepoda, Poecilostomatoida), with reconsideration of the taxonomic status of the Vaigamidae

Nineteen genera are currently considered valid in the Ergasilidae. A cladistic analysis was conducted on these genera and the five genera composing the closely allied Vaigamidae. Nineteen morphological characters were selected and polarized using Anthessius (Anthessiidae) as the outgroup. The most parsimonious cladogram (tree length = 60, Consistency Index = 0.50, Retention Index = 0.71), obtained through the use of the BB command in Hennig 86, is composed of eight major clades, with the five vaigamid genera composing the most derived clade. Based on Wiley’s (1981) “sequencing” convention, the five vaigamid genera cannot be placed in a family separate from the Ergasilidae. The biogeography of the ergasilid genera is discussed. Vaigamus spinicephalus is placed separately in a new genus, Pseudovaigamus.