Mission possible: An attempt toward a phylogenetic understanding of the genus Dendrobaena (Crassiclitellata, Lumbricidae)

With approximately 115 described species, Dendrobaena is the most species-rich genus within the family Lumbricidae and is probably also the most heterogeneous, both morphologically and geographically. Early attempts at morphological revision led to the separation of some morphologically homogeneous groups as separate genera, such as Fitzingeria and Satchellius . Although molecular phylogenetic approaches are now widely applied, relatively few studies have focused on Dendrobaena , and those have generally been limited to the revision of individual species groups. To address this gap, we employed an integrative approach combining molecular and morphological data. Our dataset includes 40 Dendrobaena taxa from diverse regions of Europe and Asia, several Eisenia species representing their entire geographic range, and representatives of related genera ( Dendrodriloides , Healyella , and Spermophorodrilus ). Our results indicate the potential polyphyly of both Dendrobaena and Eisenia , with E. ebneri and related species forming a clade with Caucasian Dendrodriloides species instead of Eisenia s. str. This clade also includes Dendrobaena veneta and closely related taxa. Within Dendrobaena , five distinct clades were recovered. According to our results, the lineage comprising former Fitzingeria species and allied taxa, and also the D. byblica species group together with Philomontanus baloutchi , do not belong to the Dendrobaena s. str. clade.