Description (from Thorne, 1974)
Body arcuate, especially in posterior third. Lateral field 1/4 body width. Lip region slightly set off with low but distinct papillae, similar to that of T. baldus. Spear 12 um long with aperture occupying 1/3 its length. Basal portion of esophagus enlarged in posterior 3/7 by gradual expansion. Cardia with prominent disc, then conoid. Granules of intestine exceedingly fine, distinctly forming a tesellation of the cells. Prerectum length 4 to 6 times body diameter. Rectum slightly longer than tail. Vulva transverse with lightly sclerotized labia. Ovaries reflexed about 1/2 their length. Two pairs of pores well back on tail.
Thonus elegans is distinctive because of the long prerectum and low papillae which are scarcely elevated above the head contour.
Habitat: Dry farm grain field near Huron, South Dakota.