Genus Protrellus Cobb, 1920

Generic diagnosis. Female: Cephalic extremity formed by lip cone and expanded second annule. Oesophageal corpus clavate. Isthmus short. Vulva anterior to base of oesophagus. Vagina and common uterus posteriorly directed, paired uteri opposed. Eggs elongate, oval or ellipsoidal, shell usually bearing longitudinal ridges or excrescences or a circular crest either laterally or towards one of the poles. Tail short, conical to attenuate.

Male: Corpus cylindrical. Caudal extremity subconical. Spicule present. Testis single. Caudal papillae 3–5 pairs.