|Female: Length = 0.55-0.77 mm;
width = 0.36-0.5. mm. Adult lemon-shaped, with prominent
neck and vulval cone.
Lip region annulated, with 6
confluent lips and a labial disc.
Spear straight to slightly arcuate, 26-32 Âµm long;
basal knobs rounded.
Median esophageal bulb rounded, with a distinct valve.
Vulva is a 12-13 Âµm long slit; may have gelatinous
extrusion, but eggs rarely, if ever, extruded. Zigzag,
rugose cuticular surface pattern. Subcrystalline layer
consipcuous, sloughing off as the dark brown cyst is
formed. This layer now known to consist of cosanoic acids
and their calcium salts (Brown et al., 1971).
Vulval cones of cysts mainly occupied by hyaline
Bullae prominent, crowded beneath vulval cone. Ambifenestrate.
Most cysts contain 200-250 eggs, but large ones may
contain more than 600 (Anderson, 1961). Average cyst size
0.71 mm x 0.50 mm (Triffit, 1929).
No yellow phase as the
maturing cyst changes from white to dark brown (Franklin,
1951). Mean of 20 eggs from neotype locality
(Aschersleben, Germany): 126 Âµm long, 56 Âµm wide.
Male: Length 1.07-1.59 mm. Abundant, vermiform,
length averaging 1.38 mm for 100 individuals (Franklin,
1951) but often much shorter--particularly those
developing in H. avenae-resistant cereals.
Body annules distinct, about 2 Âµm wide.
fields with 4 incisures, outer bands usually
Lip region rounded, offset, with 4 to 6 (usually 5)
annules; framework heavily sclerotized with conspicuously
marked outer margins. Cephalids
indistinct, anterior 1 to
2 and posterior 6 to 7 annules behind lip region.
Anterior tapering part of spear sharply pointed,
usually a little shorter than half the spear length;
basal knobs of spear rounded, usually with flat,
posteriorly sloping anterior surfaces.
Orifice of dorsal esophageal gland 3 to 6 Âµm behind
Median esophageal bulb oval with distinct valve.
glands ventral and ventro-lateral to
intestine; dorsal with larger nucleus located closely
behind esophago-intestinal junction, subventrals
extending past the dorsal.
pore near esophago-intestinal junction. Hemizonid
distinct, 2 to 3 annules long, usually 5 to 6
annules anterior to excretory pore, but occasionally only
one or 2 annules anterior. Hemizonion
indistinct, 6 to 7
annules behind excretory pore.
arcuate, with medium-sized ventral flanges
and notched end; together forming a narrow tube distally.
simple, slightly curved.
Tail end usually twisted.