Body slender, tapered to both extremities, more pronounced posteriorly. Cuticle marked by faint transverse striations. Striations interrupted by longitudinal alae, each wing area contains two longitudinal alae and occupies one-seventh body diameter at vulva. Height of lips slightly more than one-fourth width of lip region. Lip region delineated by beginning of transverse striations. Four slender cephalic setae 3.5 microns (2.6-3.5 microns), located two annules posterior to lip region. Stoma 19.5 microns (19-23.3 microns), length twice width of lip region. Cheilostom obscure. Prostom one-third length of meso-metastom. Amphids located near level of posterior half of stoma 15.5 microns from anterior extremity. Amphid diameter 3 microns (2.6-3.3 microns) occupying one-third width of neck. Esophagus about one-fourth of body length. Excretory pore slightly posterior to middle of esophagus 57.5% (51-59.5%). Nerve ring just anterior to excretory pore. Cervical papillae setiform, situated between longitudinal ridges slightly posterior to level of excretory pore. Esophago-intestinal valve length, one-half width of body at its level. Vulva equatorial 50% (48-51%). Vagina extends into body one-third body diameter at vulva. Eggs 26 microns x 54 microns. Rectum length 14.5 microns (14-23 microns). Tail length about seven (5 to 7.5) anal body diameters, tapering most rapidly in proximal one-fourth, then tapering gradually to tip. Cuticularized orifice of caudal glands (spinneret) 2.6 microns (2.6-3 microns) in length.
Male: Male similar to female; however, total length greater and excretory pore more posteriorly placed: 72% of esophagus length. Testes diorchic and opposed, occupying 54.5% of body length. Spicules asymmetrical, right spicule 32 microns; left, 26 microns long. Gubernaculum 11 microns long with prominent or conspicuous process extending anteriorly between spicules. In addition the gubernaculum has two oblique lateral processes extending beyond dorsal process. One weakly developed preanal, supplementary, non-cuticularized tubulus, and one preanal seta. Tail with eight pairs of irregularly placed caudal setae, and one ventral caudal papilla.
Holotype: Female collected January 1, 1949 by H.J. Jensen,
catalogue no. 119, University of California Nematode Survey Collection.
Paratypes: One female same data as holotype: three females collected January 8, 1948 by H.J. Jensen, Mt. Vernon, Washington.
Type habitat: Moss taken from a second growth wooded area.
Type locality: One mile south of Summit Park, Skagit County, Washington.
Plectus varians may be readily recognized by the low, rounded lip region, the relatively large amphid, and the length of the tail.
(Description- Maggenti, 1961)