Steinernema sichuanense  Mracek, Nguyen, Tailliez, Boemare & Chen, 2006

Summary: Steinernema sichuanense is characterized by male, female and IJ. For male, the spicules are robust with prominent rostrum; gubernaculum has blunt anterior end; cuneus is arrow-shaped, pointed posteriorly. Second-generation male has a prominent mucron. For female, tail usually has one to four papillae-like projections on tail tip; post anal swelling is absent. For IJ, body length is about 710 µm; lateral field has six ridges; the formula of lateral field is 2, 5, 6, 4, 2 with two prominent submarginal ridges; tail usually has a dorsal depression. In intermedium group, the IJ of S. sichuanense differs from S. affine by its absence of the internal tail spine; differs from Steinernema beddingi by its six ridges in lateral field compared to 4 for S. beddingi. For male mucron is absent in both generations of S. affine, S. intermedium and S. beddingi, whereas it is present in the second-generation of S. sichuanense. Morphology and morphometrics of spicules and gubernacula of the four species in intermedium group are quite different based on SEM photographs. For female, the postanal swelling is absent in the first-generation of S. sichuanense whereas S. affine and S. intermedium have slight swelling and S. beddingi has conspicuous swelling. The new species is further recognized by characterization of sequences of ITS and D2/D3 regions of the ribosomal DNA. The symbiotic bacterium associated to S. sichuanense belongs to the species Xenorhabdus bovienii.