Alaimus primitivus
Photo Gallery- Konza Prairie
Photo Gallery- Homestead Prairie

Female:  1.2 mm; a = 41; b = 4.3; c = 9.0; V = 39
Male: 1.0 mm; a = 55; b = 4.0; c = 12

Body tapering uniformly both ways from near the middle.  Lip region rounded, the papillae visible only under the most favorable conditions.  From a face view the vestibule is found to be triradiate, probably allowing for considerabe expansion while feeding.  Sensillae located near the end of the first third of neck.  Amphidal aperture exceedingly minute and obscure.  Esophagus a uniform tube in the anterior two-thirds then slowly expanding to form an elongate swelling similar to that of Alaimus arcuatus.  Vulva a transverse slit.  Ovary reflexed about half way to vulva.  Eggs five to six times as long as the body width.  Body tapering uniformly to the sharply-pointed, elongate conoid, arcuate tail.  Male tail, according to de Man, shorter and less tapering than that of female.  Spicula about as long as anal body diameter witha slight ventral angle.  Supplements four, appearing as low, rounded elevations.
Females of this species are rather common in Utah fields but males have not been observed.
Habitat:  The Netherlands; Sydenham, England; Erlangen, Laibach, Frankfurt and Stade, Germany.  Cultivated fields near Lewiston, Ogden, Salem and Salt Lake City, Utah, U.S. A.
(Description- Thorne, 1939)

Female:  0.99-1.05 mm; a = 47-76; b = 4-5.3; c = 5.4-7.2; V = 39-41
Male:  0.76-0.94 mm; a = 55-75; b = 4.5-4.8; c = 9-10
The foregoing dimensions are rather smaller than those given by de Man (1884) and Thorne (1939) but are based on mature adults measured by T. Goodey.

Body slender, tapering in front and behind from near middle of body.  Cuticle smooth.  Head papillae very obscure, only visible under very favourable conditions.  No special stomatal structures but mouth in the form of a minute cup leading into a narrow tube which traverses the oesophagus.  Latter a narrow tube until the terminal 1/6 or 1/7 of its length where it becomes a clavate swelling.  Tail of female long and filiform.  Male tail more or less ventrally coiled and shorter than that of female.  Spicules simple, almost straight, knobbed distally; gubernaculums absent.  4-6 pre-anal, ventro-median supplements present causing slight prominences on cuticle.
(Description- Goodey, 1963)