Steinernema cholashanense n. sp. (Rhabditida, Steinernematidae) a new species of entomopathogenic nematode from the province of Sichuan, Chola Shan Mountains, China

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 herein as Steinernema cholashanense n. sp.Steinernema cholashanense n. sp. 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 n. sp. (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.