Females. Cyst stage present. Body globose, lemon shaped, with short neck and terminal cone. Cuticle thick, with superficial lace-like pattern; D-layer absent; subcrystalline layer present or absent. Vulva terminal, nulnal slit of variable length; vulval lips not protruding. Vulva area ambi- or bifenestrate. no anal fenestration. Underbridge generally present. Bullae present or absent. Eggs retained in body; in some cases egg mass also present.

Males. Body twisted. Lateral field with four (rarely three) lines. Spicules > 30 um, slightly curved, directed obliquely, with distal extremity pointed or notched. No cloacal tubus. Tail very short, rounded.

Juveniles 2d stage. Stylet < 30 um. Lateral field with four (rarely three) lines. Oesophageal glands filling body cavity. Tail conical, pointed; hyaline part variable, generally half tail length. Phasmids punctiform.

The genus Heterodera is unique among other nematode genera because of the unusual ability of the female cuticle to transform into a tough, brown, cystlike sac, protecting the eggs which have been formed within the body. (Thorne, 1961)

Species found:           at:

H. avenae	San Luis Valley, Colorado
H. graminophila	Konza Prairie
H. iri

DNA Sequences Obtained

Specimen:	Collected:
Halsey-3A	Nebraska National Forest, near Halsey NE

Species List