Three new and a known species of Tylencholaimoidea (Nematoda: Dorylaimida) from Singapore

Abstract

Three new and a known species of soil-inhabiting nematodes belonging to the superfamily Tylencholaimoidea Filipjev, 1934 are described and illustrated from Singapore. Tantunema enigmatum n. sp. is characterised by having 0.33–0.41 mm long body; angular, distinctly offset lip region; well developed circumoral sclerotization; odontostyle slender with aperture about one-fourth of its length; simple rod-like odontophore; anterior part of pharynx slender, weakly muscular, expanding abruptly into a cylindroid basal bulb, constriction present between two parts of pharynx; expanded portion divisible into a short conical, less muscular anterior part and a posterior muscular cylindrical part with thickened inner lining; lumen of the posterior one-third of expanded portion distinctly widened and thickened; mono-opisthodelphic female genital system and short hemispheroid tail. Dorella shamimi n. sp. is characterised by having 0.58–0.62 mm long body; continuous lip region with indistinct labial papillae; labial disc absent; 10–10.5 µm long odontostyle with a large pad-like muscular structure attached on ventral side of posterior half of its length extending to the anterior part of the odontophore; odontophore asymmetrical with round, transparent, knob-like thickening; pharynx with a short terminal oval bulb; mono-prodelphic female genital system with a short post-uterine sac; short conoid tail, with rounded terminus, and males with 18–18.5 µm long, simple arcuate spicules and a single ventromedian supplement. Tylencholaimus singaporensis n. sp. is characterized by having 0.35–0.47 mm long body; distinctly offset, cap-like lip region, 4.5–5.5 µm long, slender odontostyle, simple rod-like odontophore with small but distinct basal knobs, pharyngeal expansion abrupt, mono-prodelphic genital system with no post-uterine sac, and short hemispheroid tail with distinct terminal caudal pore. Tylencholaimus intermedius Peña-Santiago & Coomans, 1996 is reported for the first time from Singapore.