Steinernema huense sp. n., a new entomopathogenic nematode (Nematoda: Steinernematidae) from Vietnam

A new entomopathogenic nematode, Steinernema huense sp. n., belonging to the carpocapsae group, was recovered in Bach Ma National Park (Thua Thien Hue province) Vietnam. Steinernema huense sp. n. infective juveniles are characterised by short body length of 527 (444-571) μm, distance from anterior end to excretory pore of 43 (38-46) μm, anterior end to end of pharynx of 116 (103-129) μm; tail length of 50 (43-56) μm, D% = 37 (34-39) and E% = 85 (79-93), H% = 44 (39-52) and in having six ridges (i.e., seven lines) in the lateral field. For first generation males, the diagnostic characters include the spicule length of 67 (60-72) μm; D% = 48 (41-61); SW% = 195 (168-238) and GS% = 76 (68-81). Both generations possess a minute filamentous mucron, which can be rudimentary in the first generation, and 23 genital papillae. Spicules are finely curved, brownish and slender with a prominent rostrum. First generation females have a non-protruding, symmetrical vulva, with double flapped epiptygma. The tail of mature females is obese with a short conical tip (peg) lacking minute protuberances, and post-anal swelling not developed. The new species is further characterised by sequences of ITS and D2-D3 regions of the ribosomal DNA. According to molecular data, the symbiotic bacterium of S. huense sp. n. is closely related to Xenorhabdus stockiae.