Nygolaimus parvus
Thorne, 1974

Description (from Thorne, 1974)
    Body twisted until heads and tails are sometimes seen only from a dorsal or ventral view.  Lip region apparently set off by slight constriction, papillae low, rounded.  Lateral field 1/4 body width.  Tooth deltoid, 22 um long, somewhat less than width of lip region. Esophagus at first a slender tube, then gradually expanding until posterior 2/3 practically fills body cavity.  Cardia elongate hemispheroid, 1/4 body width, usually obscured by cardiac glands.  Intestinal granules light brown, sometimes forming a slightly tesellated pattern.  Vulva transverse; vagina extending 2/5 across body.  Ovaries reflexed about 2/3 distance back to vulva.  Eggs 3-4 times as long as body width.  Rectum and prerectum both about as long as anal body diameter.  Males rare and apparently not functional since associated females did not contain sperms.
    Nygolaimus parvus is distinctive among the smaller species of the genus since it is the smallest of all.  The neck occupies about 1/3 of the body length and the vulva is smaller and of a different form than those of related species.
    Habitat: Native sod near Brookings, Cottonwood, Presho, Medicine Butte and other points in South Dakota; Minot, North Dakota; Elizabeth, Minnesota, and Monument Park on the Powder River, Montana.

DNA Sequences Obtained

Specimen:	Collected:
Lava LSM-48	Lava Hot Springs, Idaho