Description (from Thorne, 1974):
Body arcuate especially in posterior third, ending in a somewhat hooked tail region.  Lateral field about 1/6 body width.  Lip region angular, set off by constriction, papillae prominent.  Spear 15 um long with aperture 1/3 its length.  Extension twice spear length. Esophagus enlarged in posterior half by gradual expansion.  Cardia with narrow disc, then conoid.  Intestinal cells with bright brown, scattered granules.  Prerectum 1 1/2 times as long as body width.  Vulva transverse with pointed, sclerotized labia.  Eggs slightly longer than body width.  Uteri packed with sperms.  Males with 11 uniformly well spaced supplements, the posterior one being within range of spicula.  Prerectum reaching to a point opposite midway of the 5th and 6th supplements. Eudorylaimus robustus distinctive because of supplement arrangement and sclerotized labia of the transverse vulva.  Usually the vulva of bisexual Eudorylaimus is longitudinal.

Habitat: A single collection from native sod near Murdo, South Dakota.