Sphaerolaimus Bastian 1865

Genus Sphaerolaimus Bastian, 1865 Diagnosis (according to Fonseca & Bezerra 2014 and Tchesunov et al. 2024). Cuticle finely striated, lateral alae may be present. Inner labial sensilla papilliform, outer labial and cephalic setae setiform, usually joined in a common circle. One or two circles of eight groups of subcephalic setae posterior to the cephalic setae, significantly longer than both outer labial and cephalic setae. Subcephalic setae absent in the first two juvenile stages while present in juvenile four to adult stages. Somatic setae usually present. Amphidial fovea circular, situated at the level of the gymnostoma or further posteriorly. Buccal cavity large, barrel-shaped and the cheilostoma constitutes its major part. The cheilostoma consists of three compartments, anterior conical labial region, striated truncate conical region with fine longitudinal ribs, and broad barrel-shaped shagreen band. Gymnostoma narrow. Stegostoma short conical or truncate conical. Pharynx cylindroid, evenly muscular throughout its length, with very thick internal cuticular lining. Females monodelphic with an anterior outstretched ovary. Males diorchic with two opposed outstretched testes. Spicules mostly arcuate; gubernaculum with or without apophyses. Tail conical or conico-cylindrical with three terminal setae.