Two new species of genus Thorne, 1939 (Nematoda, Dorylaimidae) from natural parks of Vietnam with an identification key to the species with a medium-sized odontostyle.

Thorne, 1939 is a large and diverse dorylaimid genus with complicated taxonomy. Two new species, and from natural habitats in Vietnam were characterised both morphologically and molecularly (18S rDNA and 28 rDNA), and line drawings and microphotographs are provided. Phylogenetic analyses showed that the new species clustered together with Thorne, 1939, the type species of the genus. The two new taxa belong to a group of species with medium body (L = 1.5-2.5 mm) and odontostyle (31-39 μm) length, and a lip region offset by a constriction. Based on morphological and molecular evidence, this study shows that the populations from Vietnam previously identified as Rahman, Jairajpuri, Ahmad & Ahmad, 1986 in fact represent Evolutionary relationships of species are discussed. A key to the species of with a medium-sized odontostyle (31-39 μm) is provided as well as a list of the species of the genus considered valid.