Phylogeny of North European Lumbricillus, modified from Klinth et al. (2017). Species tree based on 12S, 16S, COI, 18S, 28S, ITS and H3 genes, estimated using Bayesian inference under the multispecies coalescent model in *BEAST. Posterior probabilities higher than 0.9 shown as support values. Scale shows expected number of changes per site in COI with all other genes relative to it. Lumbricillus tuba has been added to the tree at the most probable position given the other gene and species trees from Klinth et al. (2017). The tree depicts the five morpho-groups that are used in the present study to discuss the relationships within Lumbricillus. The general morphology of the spermathecae and testes/testis sacs of these groups are also shown.