Oscheius amsactae n. sp. (Nematoda: Rhabditida), a necromenic associate of red-hairy caterpillar, Amsacta moori (Lepidoptera: Arctiidae) from Kanpur district, India

Abstract

Oscheius amsactae n. sp. is described as a necromenic associate of red-hairy caterpillar Amsacta moori (Lepidoptera: Arctiidae) from Vigna radiata ((L.) Wilczek) cultivated field at Indian Institute of Pulses Research, Kanpur, India. This new species resembles with Rhabditis (O.) columbiana (Stock et al. 2005), however, it differs in having smaller body length (♀ L = 1100–1288 μm), lesser b value (b = 4.9–6.1), much smaller body length (c = 14–20.5), smaller spicule length (56–57 μm) and small gubernaculum length (20–27 μm), number of genital papillae and position of excretory pore. O. amsactae n. sp. can be compared with R. (O.) guentheri (Sudhaus and Hooper 1994) but differs in having a leptoderan bursa, different shape of spicule, number and arrangement of genital papillae. It also differs from R. (O.) necromena (Sudhaus and Schulte 1989) in having longer and narrower stoma and difference in shape of glottoid apparatus, smaller body length and shape of bursa. The new species closely resembles O. shamimi (Tahseen and Nisa (2006)) but differs in having narrower lip region (lip region diameter 7.1–7.9 μm vs. 11–12 μm in O. shamimi); shorter males (L = 594–804 μm vs. L = 1012 μm in O. shamimi). Moreover, the shape of spicule is also different, O. amsactae n. sp. has crochet-needle shaped tip of spicule whereas it is slightly curved in O. shamimi. Bursa is leptoderan in O. amsactae n. sp. whereas it is pseudopeloderan in O. shamimi. Additionally, molecular characterisation and electron microscopic studies confirm that it is distinctive from other species of the genus and it is a new species.