Genus Nacobbus
Thorne & Allen, 1944

    Nacobbinae.  Young female:  Vermiform, elongate-slender, about 1 mm long.  Cuticle distinctly annulated.  Lateral fields each with four incisures, irregularly areolated.  Phasmid pore-like, anterior to middle of tail.  Cephalic region broadly rounded, continuous, with three to four annules.  Median bulb rounded, with large refractive thickenings.  Stylet strong, about 21-25 um long, conus about as long as posterior part, knobs rounded.  Oesophageal glands elongate, extending for more than two body widths; subventral glands asymmetrical, extending past dorsal gland; nuclei of three glands lie in tandem behind oesophago-intestinal junction.  Vulva a transverse slit, located within two anal body widths of anus.  Ovary immature.  Tail tapering to a broadly rounded terminus, one to two anal body widths long.  Migratory in soil and roots.  Mature female:  Body saccate tapering anteriorly from median bulb and posteriorly from uterine region, often appearing spindle-shaped; early stage of mature female usually batatiform, with subterminal anus and vulva, very long tubular uterus, and a long, serpentine ovary reaching oesophagus; swollen body may contain several dozen eggs.  Sedentary endoparasites inciting root-galls.  Male:  Vermiform, with well-developed cephalic sclerotization.  Stylet about 23-27- um long and oesophagus structurally similar to that of immature female.  Oesophageal glands elongated, mostly dorsal to intestine.  Testis single, outstretched.  Spicules cephalated, ventrally arcuate, 20-35 um long.  Gubernaculum simple, linear to trough-shaped, fixed.  Cloacal lips not modified.  Male tail completely enveloped by a bursa.

(Description- Siddiqi, 2000)

Strong sexual dimorphism. Adult female swollen, spindle-shaped to globose. Deirids absent. Lip area rounded, not set-off (except in mature females), on the SEM; labial disc rounded, conspicuous; submedial sectors rounded, separated; lateral lip sectors reduced or absent. Oesophageal glands in line with a long dorsal overlapping of the intestine. Oesophago-intestinal valve undeveloped. Female genital tracts with anterior branch very developed; posterior branch completely regressed with no trace of postuterine sac. Vulva very posteriorly situated. Tail short, extremity rounded. Phasmids punctiform, in anterior half of tail. Gubernaculum plain, not protruding. Caudal alae enveloping tail. Forming galls on roots.

Type species
    Nacobbus dorsalis
Other species
    Nacobbus aberrans

Species found:             at:
N. aberrans Scottsbluff, NE