Morphological and molecular characterization of Aporcelaimellus obtusicaudatus (Bastian, 1865) Altherr, 1968 isolated from hilly region of India

Two populations of Aporcelaimellus obtusicaudatus were isolated from the soils of sugarcane and Paddy fields of district Dehradun (30° 19 N, 78°03 E and 960 meter above sea level), Uttarakhand, India. Based on morphological, morphometrical and molecular studies, the nematode was identified as Aporcelaimellus obtusicaudatus. Both isolates characterized by having body size 1.6–2.9 mm (SF5) and 1.8–3.1 mm (SF8) long, lip region offset by deep constriction, lips angular and 15.5–19.8 µm (SF5) and 14.5–18.8 µm (SF8) broad, odontostyle dorylemoides with wide lumen 19–22 µm long in (SF5) and 20–23 µm long in (SF8), odontostyle aperture half of its length, neck length 416–631 µm long (SF5) and 430–594 µm long (SF8), pharyngeal expansion 220.3–367 µm and 234–327.5 µm long or occupying 52-58% and 54-55% of the total neck length in both isolates, female genital system amphidelphic with transverse vulva and opaque pars refringens vaginae, tail shortand rounded to conical with inner cuticle. Molecular analyses utilizing segments of the 28S rDNA and 18S rDNA placed Aporcelaimellus obtusicaudatus in a clade with other A. obtusicaudatus reported from different geography Ireland, South Africa, China and UK. A comparative study of species of genus Aporcelaimellus is also provided.