<i>Oscheius amsactae</i>n. sp. (Nematoda: Rhabditida), a necromenic associate of red-hairy caterpillar,<i>Amsacta moori</i>(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 Stock, S P, Caicedo, A M and Calatayud, P A. 2005. Rhabditis (Oscheius) columbiana spn. (Nematoda : Rhabditidae), a necromenic species associate of the subterranean burrower bug Cyrtomeus bergi (Hemiptera: cydnidae) from the Cauca Vally, Columbia. Nematology, 7(3): 363–373. [Google Scholar]), 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 Sudhaus, W and Hooper, D J. 1994. Rhabditis (Oscheius) guentheri spn., an unusual species with reduced posterior ovary, with observations on the Dolichura and Insectivora groups (Nematoda: Rhabditidae). Nematologica, 40: 508–533. [Crossref] , [Google Scholar]) 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 Sudhaus, W and Schulte, F. 1989. Rhabditis (Rhabditis) necronema sp. n., (Nematoda: Rhabditidae), from southern Australian diplopoda with notes on its riblings R. myriophila, Poinar, 1986 and R. caulloryi, Maupas, 1919. Nematologica, 35: 15–24. [Google Scholar]) 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 Tahseen, Q and Nisa, S. 2006. Embryology and gonad development in Oscheius shamimi sp. n. (Nematoda: Rhabditida). Nematology, 8(2): 211–221. [Google Scholar])) 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.