Phylogeny of Lumbricidae based on mitochondrial genomes with emphasis on the genus Dendrobaena

Obtaining reliable phylogenies for earthworms used to be challenging due to the limited number of morphological characters and their high levels of homoplasy. Methods utilizing DNA sequences have shown promise, but the amount of available data is still limited, and comparing results from different papers that utilize different molecular markers can be difficult. Mitochondrial genomes offer a convenient tool for phylogenetic analysis: they are relatively easy to obtain and can be appended to further studies. In this study, we added 28 new lumbricid mitochondrial genomes, with a focus on little-studied taxa from the Caucasus, primarily belonging to the Dendrobaena genus. Our findings indicate that most representatives of the Dendrobaena genus formed a sister group to the other studied lumbricid genera. Notably, D. byblica did not fall within this clade, supporting the suggestion that it may belong to a separate genus. The remaining lumbricid genera mostly grouped together with several internal clades, and most remained unresolved, except for the clade consisting of Bimastos, Rapheodrilus, and Eisenia. Consistent with other studies, the genus Aporrectodea was found to be polyphyletic. Additionally, we identified several species complexes with extensive genetic diversity, including the D. schmidti and E. nordenskioldi complexes, as well as the group comprising D. veneta and D. hortensis.