Morphological and molecular characterisation of <i>Merlinius brevidens</i> (Allen, 1955) Siddiqi, 1970 (Nematoda: Rhabditida: Merlinidae) from India

Abstract

A population of stunt nematodes (P36) was isolated from the soils of vegetable fields from Meerut district, India. Based on morphological, morphometric and molecular studies, the nematodes were identified as Merlinius brevidens. The Indian strains are characterised by having females with a body length of 0.57–0.64 mm and males 0.54–0.68 mm; lip region set off with of 4–7 annules and with six lips; stylet 13–14 µm long with prominent, posteriorly sloping knobs; vulva equatorial (V = 54–58); phasmids distinct, located in the anterior half of the tail; female tail (41–54 µm long, c = 11.3–15.0 µm, c’ = 2.8–4.9) sub-cylindrical with 27–32 annules and terminus hemispherical, almost smooth, slightly set off, bluntly rounded to sometimes acute to bulb-like; male tail (45–52 µm long, c = 11.2–14.7, c’ = 3.2–4.7) bearing well-developed bursa; spicules 18–23 µm long; gubernaculum 5–6 µm long. The Indian strain agrees well with the type material described from the USA. Flanking region D2–D3 segment of 28S rRNA of M. brevidens yielded 874 bp. We also sequenced for the first time the Internal Transcribed Spacer (ITS) rRNA of M. brevidens, which yielded 876 bp. The results of the phylogenetic studies supported the morphological and molecular data.