Steinernema cholashanense Nguyen, Puza & Mracek, 2008

    During a random survey of entomopathogenic nematodes in the provinces of Sichuan and Gansu (eastern Tibet) in 2004, soil samples from several sites were collected and tested for the incidence of entomopathogenic nematodes. A new species was collected in this survey and it is described as Steinernema cholashanense. Steinernema cholashanense is characterized by morphology and morphometry of the IJ and male. For the IJ, the new species can be recognized by the average body length 843 µm, esophagus length 125 µm, H% = 39% and E% = 81%. The lateral field pattern is 2, 5, 7, 4, 2. The male of the first generation is characterized by spicule shape and length and especially with prominent velum and the presence of a mucron on both generations. The average body length of the IJ of S. cholashanense (843 µm) is shorter than that of S. oregonense (980 µm), S. kraussei (951 µm) and S. litorale (909 µm), similar to that of S. feltiae (849 µm), but longer than that of S. weiseri (740 µm), S. jollietti (711 µm) and S. hebeiense (658 µm). Esophagus length of the new species (125 µm) is closer to that of S. jollieti (123 µm) but longer than that of S. weiseri (113 µm) and shorter than that of S. oregonense (132 µm), S. kraussei (134 µm) and S. feltiae (136 µm). E% of the new species (81) is similar to that of S. kraussei (80), but smaller than that of S. jollieti (88), S. weiseri (95), S. oregonense (100) and S. feltiae (119). Spicule head length of the new species is almost the same as its width, this character is similar to that of S. kraussei but it is different from this species by its prominent velum. The new species can be recognized further by characteristics of sequences of ITS and D2D3 regions and cross hybridization with closely related species, S. feltiae, S. kraussei and S. oregonense.