Description (from Thorne and Malek, 1968)
Bodies cylindroid except toward extremities. Striae variable the coarsest being about 1.7 um apart. Lateral fields a plain band about 1/6 body width, usually with two exceedingly minute incisures. Lip region set off by constriction. Spear 12 um to 15 um long with slight but distinct knobs. Details of bulb, nerve ring and excretory pore as illustrated. Hemizonid obscure, about 1 body width behind pore. Intestinal cells each with single nucleus, sometimes very small and grouped closely in region of vulva as illustrated. Vulva with sclerotized, overlapping, jointed flap. Ovary outstretched, sometimes reflexed. Posterior uterine branch a broad tubular sac usually filled with sperms. Terminal cells of intestine without granules. Tail slightly arcuate with blunt terminal projection. Male with arcuate tail bearing 3 pairs of papillae. Spicula 18 um long, broad, slightly arcuate with thickened blunt, rounded terminus, very different from those of other species.
Aphelenchoides vigor is distinctive because of the sclerotized anterior vulva labium, thickened terminus of spicula, small spear knobs, single nucleus of intestinal cells, and excretory pore passing through cuticle at a sharp angle.
Habitat: Prairie sod near Sidney and Powder River, Mont., Dunniston and Rugby, N. Dak., and Howes, S. Dak. Apparently limited to higher areas of the northwest Great Plains.