Mononchus papillatus
Bastian, 1865
Female:  length 1/11". breadth 1/250".
External characters- Body opaque-white in colour, tapering slightly anteriorly, but gradually to a point posteriorly.  Head truncate; mouth surrounded by four well-marked papillae.  Integument with longitudinal striae, about 1/10000" apart.
Pharyngeal cavity a little removed from anterior extremity, proportionally rather small, 1/714" long; tooth single.  (Esophagus 1/4 of total length.  Intestinal cells containing yellowish-coloured granules.  Anus 1/166" from posterior extremity.  Vulva at commencement of posterior third of body.  Uterus bifid.
Male not seen.
Habitat:  Between the sheaths of the leaves, at the lower part of culm of Festuca elatior, Broadmoor, Berks
(Description- Bastian, 1865)

Dimensions of Oregon Specimens
Five females:  L = 1.0 mm (0.9-1.3); A = 26 ( 22-30); B = 3.6 (3.2- 4.0); C = 12 (9-13); V = 62% (60-65); buccal cavity = 12x 24u (10-16 x 23-25); tail length = 0.08 mm (0.08 -0.1); egg = 46 x 96u.
Two males:  L = 1.27-1.37 mm; A = 28-31; B = 3.6; C = 23-24; spicule = 52-70u; gubernaculum = 19-20u; buccal cavity = 12 x 28u.

Female.  Body curves in open "C" shape when relaxed by heat;  blunt anterior termini and conoid-arcuate posterior termini.  Labial region set off by depression with distinct lips and nerve canals.  Buccal cavity thick-walled, about twice as long as wide, with large dorsal tooth in anterior fourth of cavity, opposed by a longitudinal thickening of buccal walls. Amphid apertures large, at level of dorsal tooth, about one-third as wide as corresponding cavity width.  Esophagus with nerve ring and excretory pore at anterior third.  Didelphic with reflexed ovaries.  Tail conoid-arcuate without caudal glands and spineret, usually with two pairs of caudal pores (one dorsal pair in anterior third of tail and one ventral pair in posterior third of tail).
Male. Details of labial, buccal, and esophageal regions similar to those of female.  Posterior region with thirteen uniformly shaped supplements beginning within range of spicules.  Spicules thick, crescent-shaped; gubernaculum crescent-shaped, with thickened keel-like area, without accessory pieces.  Remainder of caudal region resembles that of female.

Habitat:   By far the most widely spread species of Mononchoidea in Oregon, M. papillatus occurs in a great variety of cultivated and noncultivated areas.
(Description- Jensen and Mulvey, 1968)