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Lumbricillus is one of the largest enchytraeid genera and its species can mainly be found on the coasts of temperate and polar regions around the world. However, the monophyly of the genus has been questioned by recent molecular studies. In this paper we further examine the phylogenetic relationships of Lumbricillus species and their close relatives by estimating a phylogeny of 62 species, many collected along the Norwegian coastline, with seven genetic markers. We confirm Lumbricillus to be non-monophyletic and resolve this issue by establishing the new genus Paralumbricillus, into which ten of the known species are transferred: Paralumbricillus arenarius, Paralumbricillus cervisiae, Paralumbricillus christenseni, Paralumbricillus crymodes, Paralumbricillus dubius, Paralumbricillus eltoni, Paralumbricillus eudioptus, Paralumbricillus muscicolus, Paralumbricillus nielseni, Paralumbricillus westheidei, all comb. nov. In this paper we also describe eight new species: Lumbricillus bibulbus, L. boreas, L. elisae, Paralumbricillus bicornis, P. bilobatus, P. lofotensis, P. sanguineus, and Claparedrilus torquatus.

Abstract Background Deep mitochondrial divergences were observed in Scandinavian populations of the terrestrial to semi-aquatic annelid Fridericia magna (Clitellata: Enchytraeidae). This raised the need for testing whether the taxon is a single species or a complex of cryptic species. Results A total of 62 specimens from 38 localities were included in the study, 44 of which were used for species delimitation. First, the 44 specimens were divided into clusters using ABGD (Automatic Barcode Gap Discovery) on two datasets, consisting of sequences of the mitochondrial markers COI and 16S. For each dataset, the worms were divided into six not completely congruent clusters. When they were combined, a maximum of seven clusters, or species hypotheses, were obtained, and the seven clusters were used as input in downstream analyses. We tested these hypotheses by constructing haplowebs for two nuclear markers, H3 and ITS, and in both haplowebs the specimens appeared as a single species. Multi-locus species delimitation analyses performed with the Bayesian BPP program also mainly supported a single species. Furthermore, no apparent morphological differences were found between the clusters. Two of the clusters were partially separated from each other and the other clusters, but not strongly enough to consider them as separate species. All 62 specimens were used to visualise the Scandinavian distribution, of the species, and to compare with published COI data from other Fridericia species. Conclusion We show that the morphospecies Fridericia magna is a single species, harbouring several distinct mitochondrial clusters. There is partial genetic separation between some of them, which may be interpreted as incipient speciation. The study shows the importance of rigorous species delimitation using several independent markers when deep mitochondrial divergences might give the false impression of cryptic speciation.

The intertidal fauna of the Antarctic Peninsula has a relatively high species diversity, due to its warmer environment compared to other parts of Antarctica. Marine oligochaetes are, in general, one of the most diverse and ecologically important benthic organism groups, at least in the littoral zone. Antarctica has been one of the least studied areas with regard to oligochaete diversity. Here we report two Lumbricillus species (Lumbricillus antarcticus Stephenson, 1932 and Lumbricillus sejongensis sp. nov.) new to Antarctica, found in a tidal pool on the Barton Peninsula, King George Island. The diversity of this genus remains poorly known for Antarctica and the Subantarctic islands, and what we know is based on a few patchy studies.

We report on the Scandinavian distribution of two earthworm species, Helodrilus oculatus and Satchellius mammalis. Both appear relatively new to the Scandinavian Peninsula, as they were not included in the monographic revisions of the earthworm fauna of Sweden and Norway in the mid-1900s. We provide recent records of both species from Norway and Sweden, H. oculatus also from Denmark, and haplotype networks of four markers (COI, 16S, H3, and ITS2) are used to visualise the genetic diversity within each species. There is moderate genetic variation in COI for both taxa, and for H. oculatus, there is a West-East division between the specimens from Norway, Gothenburg (western Sweden) and Bavaria (Germany), and the ones from eastern Sweden and the Bornholm island (easternmost Denmark). This could potentially be explained by different origin and colonisation routes. In the other markers the variation is limited, and in the nuclear genes no pattern to support this split is seen. We also analyse the phylogenetic positions of H. oculatus and S. mammalis in the family Lumbricidae by combining our data (including also some 12S, 18S and 28S sequences) with a published dataset. We conclude that neither Helodrilus nor Satchellius are monophyletic. Helodrilus oculatus (type species of Helodrilus), however, forms a clade with some of its current congeners.

DNA barcoding is an invaluable tool to identify clitellates, regardless of life stage or cryptic morphology. However, as COI (the standard barcode for animals) is relatively long (658 bp), sequencing it requires DNA of high quality. When DNA is fragmented due to degradation, alternative barcodes of shorter length present an option to obtain genetic material. We attempted to sequence 187 clitellates sampled from springs in Iceland. However, the material had been stored at room temperature for two years, and DNA of the worms had degraded, and only three COI sequences were produced (i.e.,