Steinernema
everestense Khatri-Chhetri
et al., 2011
Summary
– A new species of entomopathogenic nematode, Steinernema everestense,
was recovered from soil samples collected from Pakhribas, Dhankuta district of
Nepal, during a survey in 2007. The analysis of ITS-rDNA and D2D3 LSU sequences
placed S. everestense in the feltiae group. The nematode can be
separated from other described species of Steinernema by morphological
and morphometric characteristics and by characterisations and phylogeny
inferred from DNA sequences of the D2D3 LSU or ITS regions of rDNA. For
infective juveniles, the new species can be recognised by the body length of
775 (705-838) μm, pharynx 119
(110-130) μm long, H% = 61 (47-68) and E% = 78 (60-89). The lateral field
pattern is 2, 8, 6, 4, 3. The males have well curved, brownish-yellow spicules
with a prominent but short velum, gubernaculum plump, boat-shaped to almost
straight in lateral view, cuneus long, needle-shaped, corpus with two wings in
ventral view. Spicule and gubernaculum length of the first generation males is
79 (65-87) μm and 50 (39-57) μm, respectively. A tail mucron is
present in both male generations. Genital papillae total 23 or 25, comprising
11 or 12 pairs and a single midventral papilla. Specimens with 23 genital
papillae have eight precloacal pairs (seven pairs subventral and one pair
lateral), two pairs subterminal and one pair subdorsal. The most posterior two
pairs are consistently located near the tail tip. The specimens with 25 genital
papillae have an extra adcloacal pair of papillae and the anteriormost two
pairs are close together. The vulva is slightly protruding, mostly with equal
lips, and low epiptygmata. A post-anal swelling is developed in most first and
all second generation females.