Taxonomic assessment of Lumbricidae (Oligochaeta) earthworm genera using DNA barcodes

The family Lumbricidae accounts for the most abundant earthworms in grasslands and agricultural ecosystems in the Paleartic region. Therefore, they are commonly used as model organisms in studies of soil ecology, biodiversity, biogeography, evolution, conservation, soil contamination and ecotoxicology. Despite their biological and economic importance, the taxonomic status and evolutionary relationships of several Lumbricidae genera are still under discussion. Previous studies have shown that cytochrome c oxidase I (COI) barcode phylogenies are informative at the intrageneric level. Here we generated 19 new COI barcodes for selected Aporrectodea specimens in Pérez-Losada et al. [1] including nine species and 17 populations, and combined them with all the COI sequences available in Genbank and Briones et al. [2] for Lumbricidae (435 sequences) and seven other Lumbricina families (480 sequences). Our maximum likelihood and Bayesian trees indicate that the genera Aporrectodea, Allolobophora, Eisenia and Dendrobaena (Lumbricidae) and Diplocardia, Metaphire and Amynthas (Megascolecidae) are polyphyletic and so invalid as currently defined. Our results also confirm that COI barcodes are a good proxy for estimating intrageneric phylogenetic diversity and relationships in earthworms.

► Systematics of 32 Lumbricina genera is assessed using 915 COI and phylogenies.
► Aporrectodea, Allolobophora, Eisenia and Dendrobaena (Lumbricidae) are polyphyletic.
► Diplocardia, Metaphire and Amynthas (Megascolecidae) are polyphyletic.
► Earthworm classification needs taxonomic revision.
► COI barcodes are a good proxy for estimating intrageneric phylogenies.