New data on morphology and molecular affiliations of two species of Dicelis Dujardin, 1845 (Cephalobomorpha, Drilonematoidea) parasitic in lumbricids

摘要

Recent finding of two species of Dicelis Dujardin, 1845 parasitising lumbricids has added information on morphology and molecular affiliations of Dicelis members. The morphology of D. ussuriensis from the type locality and newly recovered D. rubidi and D. kimmeriensis was examined by SEM and the three species compared. The structure of the head end appeared to be very similar in all three species. Molecular analysis showed that D. kimmeriensis separated more strongly from the rest of the genus, which is in agreement with its morphological peculiarities. In pairwise nucleotide differences in the D2-D3 LSU rDNA region, D. kimmeriensis was at equal distance from congeners and free-living cephalobids. Dicelis rubidi from Khabarovsk Krai differed from the type locality specimens in 7 bp, which was regarded as intraspecific variation. On the phylogenetic tree, the species of Dicelis from the Western part of Palearctic were in the basal position in relation to Asian species, which formed the well supported subclade.