Aquatides aquaticus
Thorne, 1930
                                        Syn.: Nygolaimus aquaticus Thorne, 1930
                                                Nygolaimus (Aquatides) aquaticus (Thorne, 1930) Heyns, 1968

Measurements (from Thorne, 1974)
L = 2.2-2.6 mm; a = 46; b = 4.3; c = 70; V = 50
L = 2.2 mm; a = 47; b = 4.0; c = 61; T = 56

Description (from Thorne, 1974)
    Body cylindroid, slightly arcuate, tapering near extremities.  Lip region rounded with papillae slightly elevated.  Tooth cylindroid, 18-20 um long.  Anterior fourth of esophagus slender, then gradually expanded to form the massively muscled basal two thirds.  As Heyns, 1968, observed, many specimens exhibit a distinct sheath about the basal portion of the esophagus which was overlooked by the writer in the original description.  Cardia obscured by cardiac glands, except on rare occasions.  Intestine packed with small dark granules.  Vulva transverse with strong labial muscles.  Vagina somewhat conical.  Ovaries reflexed halfway to vulva, the uteri acting as spermathecae.  Prerectum length twice body diameter.
    Male generally slightly smaller than females with posterior 1/5 somewhat ventrally bent.  Supplements 4-5, mammiform.  Spicula massive, slightly arcuate with cephalated lateral guiding pieces.  In general specimens from the Great Plains area are somewhat larger than those originally described from lakes in mountains of Utah.
    Habitat: Soil from stream bank west of Brookings, native sod near Faith and Huron, South Dakota and Rugby, North Dakota.