Steinernema meghalayensis sp. n. (Rhabditida: Steinernematidae) from Northeastern Hilly Region of India

A new species of entomopathogenic nematode, Steinernema meghalayensis sp. n. isolated from the Farm area of Shillong district of Meghalaya state located in the north-eastern region of India, is described and illustrated along with a brief note on its biology. The description is based on its morphological features as well as molecular characerisation of ITS region of rDNA. Its infective juveniles (IJs) are diagnosed by having 430–630µm long body, excretory pore located 32–40 µm from anterior end, continuous head without horn-like structures, 6 incisures in lateral field, and 44–58 µm long tail, D=29–38%; E = 60–82.6%; first generation males having 1210–1450 µm long body, 25 genital papillae, 65–78 µm long spicules, 45–60µm long gubernaculums; first generation females having L=5100–7530µm; excretory pore= 74–94µm; V= 49.5–64 µm; tail= 21–40µm. Tail mucro is present in females and males of both the generations. The ITS region of rDNA was amplified which was found to be of 995 base pairs (bp), comprising partial 18S, ITS 1, 5.8 S, ITS 2 and partial 28 S subunits of 172, 279, 157, 327and 61 base pairs, respectively. Multiple alignment of its base sequence with four closely related species revealed 123 diagnostic characters. Phylogenetic tree based on the ITS base sequence placed S. meghalayensis sp.n. in carpocapsae group forming a clade alongwith S. scapterisci, S. tami, S. siamkayai and S. carpocapsae having 88, 89, 90 and 99% identity, respectively. The new species could infect the larvae of Galleria mellonella, induce mortality, multiplied and emerged from the cadavers within 6–8 days at a temperature rage of 20–30⁰C. This is the first new species of this genus from Eastern Himalayan region of India.