| Male:
Vermiform, with a very short, bluntly rounded tail. Body
adopting a characteristically curved position on heat
relaxation, the posterior part often twisting through 90
degrees about the long axis. Cuticle regularly
annulated, 4 incisures in
lateral
field, appears
un-areolated under the light microscope, but is so SEM.
Head offset with prominent head cap and 5 to 6 annules. Head skeleton hexaradiate, heavily sclerotized.
Anterior and posterior cephalids
at level of second and
eighth to ninth body annules, respectively.
Well developed stylet, anterior portion 45% of total
stylet length, knobs rounded with anterior faces sloping
backward. Stomal lining forming a lyre-shaped tube around
stylet shaft, extending from basal plate of head skeleton
for 60% of stylet length.
Median esophageal bulb a slender ellipse with
prominent crescentic valve plates.
Dorsal and sub-ventral esophageal gland lobes
distinct, both lobes extending beyond excretory
pore, but
subventral lobe longer, extending to 15% of body length
from head. Dorsal gland nucleus prominent, sub-ventral
gland nuclei obscure.
Broad nerve ring encircling esophagus between median
bulb and gland lobes.
Hemizonid
distinct, 2 annules long, usually 5-7
annules anterior to excretory pore, but in one specimen,
it was only 1 annule anterior to the excretory pore. Hemizonion
not seen.
Testis
single, about 50% of total body length, packed
with dense, spherical sperm and terminating in a
glandular-walled vas deferens with narrow lumen.
Cloacal aperture small, surrounded by a raised
collar-like lip.
Spicules stout, curved with inner faces reflexed
inward and interlocked proximally to form a tube. Spicule
tips broad and said to be tridentate by many authorities,
but this character is difficult to resolve with light
microscope, and electron microscope studies indicate that
the spicules have bidentate tips.
Gubernaculum
a simple
rod.
Phasmids and caudalids not observed.
|
Female: Body
swollen, lemon-shaped, with projecting neck containing
the esophagus and part of esophageal
glands, bearing the
head with one to three projecting head annules. Anterior
part of neck irregularly annulated, remainder of body
without annulations or lateral incisures, but covered
with reticulate ridges forming a brickwork-like pattern.
Head skeleton weak, hexaradiate. Anterior part of
stylet about 50% of stylet length and often detached in
preserved specimens, stylet knobs rounded. Stomal lining
forming a complex, lyre-shaped tube around stylet shaft,
extending back from basal plate of head skeleton for 70%
of stylet length.
Median esophageal bulb large, sub-spherical, with
prominent oval valve.
Esophageal glands in broad lobe, often displaced by
massively developed paired ovaries.
Prominent excretory pore at base of neck.
Vulva and tail region carried on an obtuse cone-shaped
projection opposite the neck, the vulva a transverse slit
surrounded dorsally and ventrally by thin-walled crescent
shaped areas leaving the vulva on a thicker-walled
bridge-like structure. Vagina supported proximally by
strongly developed lateral bands of muscle. Fenestral
region surrounded by a zone of thickened cuticle. The
fenestral region is at the posterior pole of the body
with the anus in a dorsal position.
Females are white on emergence from the root cortex
and remain so throughout their development, turning brown
at death. Females produce a gelatinous egg sac, exuded
through the vulval aperture, into which some individuals
lay a few eggs (Jones, 1950).
Cyst: Lemon-shaped with protruding
neck and vulval cone, but irregularly formed specimens
are common. Ambifenestrate. Vulval region may be intact
in new cysts, but in older specimens, the thin-walled
cuticle of the terminal region is lost, leaving an open
fenestra crossed by a vulval bridge bearing the vulval
slit and dividing the fenestra into two semi-circular
semifenestrae. The lateral muscles attaching the proximal
part of the vagina to the body wall remain as an
underbridge and the vagina remains as a sheaf-like
structure between the vulval bridge and underbridge.
Cyst wall dark brown and tough, with a thickened,
strongly pigmented zone surrounding the fenestra.
Bullae
absent. Cyst wall bearing ridges forming a reticulate
brickwork-like pattern. Subcrystalline layer not visible
under light microscope, but a very fine layer is apparent
with SEM. The egg sac is usually lost from cysts
recovered from soil.
|
|
Second-stage juvenile: Folded 3 times
in egg. Vermiform, with regularly annulated cuticle, 4
incisures in lateral
field along most of body, reduced to
3 at anterior and posterior.
Lateral
field appears un-areolated under the light
microscope, but is so in the SEM. Cuticle thicker for
first 7-8 body annules.
Head slightly offset with 2-3 annules, a
dorsoventrally elongate oral disc and lateral lips
bearing amphid
apertures--these characters are shown by
SEM. Head skeleton massive, hexaradiate, often obscuring
stylet tip. Cephalids
at second and eighth annules behind
head.
Stylet robust, knobs varying from smoothly rounded to
slightly hook-shaped with recurved anterior surfaces.
Stomal lining forming a lyre-shaped tube around stylet
shaft extending from basal plate of head skeleton for
about 60% of stylet length.
Anterior part of esophagus as in male. Esophageal
glands in an elongate lobe, extending for 33% to body
length from head; broad posteriorly, dorsal gland and
sub-ventral gland lobes less distinct than in male, but
distinguishable by texture; both lobes extend beyond
excretory pore. Dorsal gland nucleus prominent,
sub-ventral gland nuclei indistinct.
Nerve ring as in male. Hemizonid
2 annules wide, 1
annule anterior to excretory pore. Hemizonion
less than 1
annule wide, 7 or 8 annules behind excretory pore.
Genital primordium a distinct two-celled structure
about half-way along body.
Tail tapering uniformly to a finely rounded terminus,
posterior 60% of tail hyaline. Hyaline portion of tail
often seen to contain 1 or 2 minute refractive bodies of
unknown composition. Caudalids and phasmids
not observed.
|