Body cylindroid, tapering but little anteriorly. Cuticle finely annulated, the coarsest striae near the head being only 1.7u apart while near midbody they are less than 1u. Lateral fields with four obscure incisures, the middle two usually disappearing near anal region. Lip region low, flattened, almost 4 times as wide as high, bearing 2 annules. Spear 17u long with peculiar shaped knobs. Isthmus slender, more than twice as long as body width, with nerve ring slightly anterior to middle. Excretory pore and hemizonid opposite ring. Esophageal lobe an outstanding feature, being more than twice as long as body width. Ovary outstretched with oocytes in single file except for a short region of multiplication. Posterior uterine branch shorter than body diameter. Tail slightly bent with phasmids near middle. Males unknown.
Pratylenchus tenuis is distinctive because of the low, flattened lip region, slender spear with distinctive shaped knobs, long isthmus and unusually elongate esophageal lobe.
Habitat: Cultivated field 2 miles west of Avon, South Dakota
(Description- Thorne and Malek, 1968)