Description (from Thorne, 1974):
Body slightly arcuate, ventrally bent posteriorly in male. Lateral field about 1/3 body width without visible cells. Lip region angular with conspicuous papillae. Spear 20 um long with aperture 1/3 its length. Guiding ring refractive, 1/4 head width. Esophagus expanded rather abruptly in basal 3/7. Cardia conoid, about as long as body width. Intestine with fine, dark, refractive granules. Vulva longitudinal. Ovaries reflexed about 1/2 their length. Uteri forming huge spermatheca packed with sperms; as many as 5 eggs observed in one female. Prerectum length about twice body diameter. Rectum slightly longer than tail. Spicula unusually long, extending to a point almost opposite first supplement.
Eudorylaimus andrassyi is distinctive because of its size, tail forms, and especially number and arrangement of supplements.
Habitat: Grain field, Barnesville, Minnesota; and about roots of young willows, Behrens Ranch, South Dakota.