Morphological and molecular characterisation of Trachactinolaimus nanjingensis n. sp. (Dorylaimida: Actinolaimidae) from Nanjing, China

Summary Trachactinolaimus nanjingensis n. sp. isolated from mosses at the Yangshan Quarry Park in Nanjing, P.R. China, is described. It is characterised by 3.01 (2.64-3.42) mm long female and 2.84 (2.50-3.22) mm long male, four onchia with numerous mural denticles (>100), vulva with a transverse slit, 15-19 contiguous ventromedian supplements, spicules length of 61.5 (54.6-64.3) μm, and female and male both having long tail, with c′ values equal to 5.0-9.2 and 2.3-3.5, respectively. The new species was morphologically compared with T. brevicaudatus, T. dominicus, T. montanus and T. radulatus. The sequences of 18S and 28S rRNA genes of the new species were obtained using regular PCR amplification, while the ITS and mtCOI sequences were extracted from the whole genome sequencing assembly. The phylogenetic relationships of the new species were reconstructed using 18S and 28S sequences and the status of the new species was discussed. The 18S and 28S sequences of a population of genus Westindicus recovered during the present study were also obtained. This is the first time to present the ITS and mtCOI sequences of family Actinolaimidae.