Pratylenchus scribneri
Steiner, 1943
Syn. Tylenchus penetrans Cobb, 1917
Pratylenchus penetrans Filipjev and Stekhoven, 1941

Description (from Thorne & Malek, 1968)
Bodies almost straight when relaxed.  Incisures 4. Labial annules 2, usually distinct. Spear15u-17u long with slightly cupped knobs. Annules near midbody about 1.2u wide.  Isthmus shorter than neck width.  Basal esophageal bulb massive, almost filling neck cavity with short ventral extension. Excretory pore and hemizonid about opposite middle of basal bulb.  Ovary outstretched, oocytes in single file except for short region of multiplication. Spermatheca or spermagonium not seen. Posterior uterine branch about equal to body width. Vulva-anus distance about 3 times tail length. Tail conoid to broad, rounded terminus.

Pratylenchus scribneri is distinctive among the 2-annuled lip species because of spear form, short isthmus, position of pore and hemizonid, massive basal bulb, longer posterior uterine branch and 3:1 ratio of vulva-anus distance to tail length.
Habitat:  Generally distributed in small numbers thoughout the region in both prairie and cultivated soils, especially those of lighter texture.  A severe pest of potatoes in the Platte River Valley of Nebraska.

Description (from Sher & Allen, 1953)
    Female: Cuticle with transverse striations about 1 um apart.  Lateral field marked by four incisures.  Lip region rounded, set off from body, bears two annules.  Outer margins of heavily sclerotized labial framework extend into body laterally about one body annule. Spear-guiding apparatus extends posteriorly from basal plate about four body annules. Spear 17 um long, broadly rounded basal knobs.  Hemizonid just anterior to excretory pore, about two body annules long.  Ovary does not extend to esophagus, consists of a single row of oocytes except for a double row near anterior end.  Oviduct cellular, uterus short.  Spermatheca or spermatozoa not seen.  Posterior uterine branch short, slightly longer than the width of the body at the vulva.Tail rounded, no striations around terminus.
    Male: Similar to female.  Single outstretched testis consists of a double row of spermatocytes for most of its length.  Phasmids slightly posterior to middle of tail extend into bursa slightly.  Spicula arcuate, hafted, rest upon a simple trough shaped gubernaculum.

DNA Sequences Obtained

Specimen:	Collected:
BVTC-1	Beltsville MD, in tissue culture plate
BVTC-2	Beltsville MD, in tissue culture plate
Canada 1	Idaho
Canada 8	Idaho
Canada 6	Idaho
BK-11	Florida