Cryptic diversity in supposedly species-poor genera of Enchytraeidae (Annelida: Clitellata).

Using a two-step workflow, we test the species boundaries in three genera of enchytraeid worms, Globulidrilus , Hemifridericia and Stercutus (Clitellata: Enchytraeidae), which contains one to three nominal species each. For the species discovery phase, DNA barcode-based clustering analyses in ABGD (Automatic Barcode Gap Discovery) are performed, using mitochondrial cytochrome c oxidase subunit I (COI) data. The clusters from these analyses are then used as input in the species validation phase, where multispecies coalescent-based multilocus species delimitation analyses are performed in BPP (Bayesian Phylogenetics and Phylogeography) using nuclear Histone 3 (H3) and Internal Transcribed Spacer (ITS) data. For all BPP analyses, several species delimitation arrangements are included in the 95% credibility interval, and no complete sets of species are well supported. However, we conclude that our data set comprises at least seven species of Globulidrilus , all attributed to the nominal morpho-species G. riparius , three species of Hemifridericia , whereof two are cryptic lineages within H. parva and one is H. bivesiculata , and at least six species of the previously monotypic Stercutus. The species are not formally described here due to a lack of mature specimens of many of them in combination with low support for some of them in the genetic analyses. However, this is the first step towards a better understanding of the diversity within these groups. [ABSTRACT FROM AUTHOR]