Bodycylindroid, slightly arcuate.  Lateral field 1/3 body width. Lips angular, set off by constriction, about 1/3 with of neck base.  Spear 13u long with aperture occupying 2/5 its length.   Esophagus enlarged near middle by rather abrupt expansion.  Cardia elongate conoid with prominent disc between esophagus and intestine.  Intestine granules very fine and refractive.  Rectum about as long as body diameter, prerectum about twice length of rectum.  Vulva transverse with refractive labia.  Vagina extending slightly more than halfway across body.  Ovaries reflexed 1/2 to1/3 distance back to vulva.  Tail dorsally convex to rounded terminus with two pairs of pores.  Obscure traces of saccate glands sometimes present.  Supplements 5 or 6, rather variably spaced, the first being slightly anterior to spicula.

Thonus nothus is distinctive because of its small size, length of spear, elongate conoid cardia and number and arrangement of supplements.
Habitat: Blue grass field near Long Lake and mountain meadow in Black Hills, South Dakota.