DNA barcoding and genetic distances in three genera of Naididae (Annelida: Clitellata)

Identification of organism groups such as Oligochaetes to species level is difficult to achieve using morphological examination alone. This is especially true in species where sexual reproduction is rare, such as the subfamily Naidedae. Here, variation in the barcoding marker COI of three genera of freshwater clitellates, Dero, Nais, and Pristina (Clitellata: Naididae) was studied, using publicly available sequences together with newly generated ones, with the aim to test for the presence of global barcode gaps. In total 17 sequences of Dero spp., 168 of Nais spp., and 22 sequences of Pristina spp. were included in the analyses. The uncorrected pairwise distances in the Dero dataset ranges from 0.00 to 0.18, in the Nais dataset they range from 0.00 to 0.21, and in the Pristina dataset they range from 0.00 to 0.36, with a large gap between 0.21 and 0.35. No global barcoding gap was found in any of the datasets. In all three genera clusters including more than one species and/or species found in more than one cluster were found, indicating taxonomical problems, such as cryptic species and misidentified sequences.