Re-description of Oscheius chongmingensis (Zhang et al., 2008) (Nematoda: Rhabditidae) and its entomopathogenicity

A population of Oscheius chongmingensis was isolated from a soil sample collected from an alfalfa field in the vicinity of Hailar, Inner Mongolia, and was designated as the Tumian strain. This nematode has a facultative entomopathogenic activity and reproduces on the Galleria mellonella larvae. We compared our isolate with the original description of O. chongmingensis, checked several paratype slides of this species and compared it with cultures of the original Shanghai strain. Poor morphology, morphometrics and some errors in the original description of O. chongmingensis encouraged us to re-describe this species. The species is characterised by having five distinct ridges in the lateral field in adults.. The stoma of O. chongmingensis is long and narrow, in adults approximately 3.5-4.5 times as long as wide, whereas in dauer juveniles it may be 6-7 times longer than wide. Males possess a ventral pair of small bristle-like sensilla posterior to the cloacal opening. Both the Tumian and original strain are amphimictic with a higher proportion of females, but males are not rare (ca 2.5:1).