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Description (from Thorne & Malek, 1968)
Lateral
fields marked by 6 incisures except toward extremities where they are
reduced in number. Near midbody these incisures may be broken into
irregular lines. Lip
region bearing two annules. Spear
14u
long
with somewhat rounded knobs. Esophageal gland outlet near spear base.
Valve of median
bulb anterior to center. Nerve ring surrounding base of isthmus. Basal
bulb with overlap about as long as body width. Hemizonid just anterior
to excretory pore. Anterior ovary outstretched with oocytes arranged
in single file except for short region of multiplication. Posterior uterine
branch about as long as body width. Tail
slightly
convex-conoid to broad, rounded terminus, with about 20 obscure annules.
Males unknown.
Pratylenchus hexincisus is distinctive because of the six incisures, somewhat rounded spear knobs and broad rounded terminus of the convex-conoid tail.
Habitat: Corn fields, Experiment Station Farm, Brookings,
and Oakwood State Park, South Dakota. Probably generally distributed in
heavier soils of South Dakota.
Description (from Taylor & Jenkins, 1957)
Female: The short and somewhat stout body
tapers towards both ends. The cuticle is marked with transverse striations
about one micron apart, occurring slightly farther apart on the tail of
some specimens. The lateral field occupies about one-third of the
body diameter in the vulvar region, originates as a narrow groove at the
base of the stylet guiding apparatus, and contains six incisures throughout
most of its length. Outer incisures are crenate while the inner incisures
are somewhat irregular, particularly in the vulvar region where breaks
and oblique lines frequently occur. Only four incisures occur on
the tail. No cervical papilla (deirid) was observed. Phasmids
occur in the anterior 1/4 - 2/5 of the tail. The unstriated tail-tip
is rounded.
The low, flattened lip region bears one striation
and its lateral margins are rounded in outline. Lateral margins of
the sclerotized cephalic framework extend posteriorly about one micron
into the body cavity. The stylet guiding apparatus is 3.2-3.6 um
long. The short, stout stylet has spherical basal knobs.
The dorsal esophageal gland duct opens into the
slightly convoluted lumen of the esophagus 2.2 um posterior to the
stylet base. The esophagus consists in part of the distinct corpus
and an ovoid middle bulb which contains a heavily sclerotized valvular
apparatus. The excretory pore is located in the region of the isthmus;
the nerve ring surrounds this same structure. Esophageal glands ventrally
overlap the intestine, which contains granules that are larger and more
dense towards the ventral surface. The dorsal esophageal gland nucleus
is larger than the subventral nuclei. The intestine terminates in
an oblique rectum that opens through the cuticle by means of a conspicuous
anus.
The single outstretched ovary extends anteriorly
about one-half of the body length. Except for a double row in the
anterior portion, the ovary contains a single row of oocyes. An oviduct
connects the ovary and the cellular uterus. The cuticularized vagina
extends transversely about one-half the body diameter and opens by means
of a prominent vulva. The short post-uterine branch is about equal
to the body diameter at the vulva. No spermatheca was observed.
Male: Unknown.
Type host: Roots of corn, Zea mays.
Type locality: Le Cates farm, Kent County, Maryland.
DNA Sequences Obtained
Specimen: | Collected: |
KonzaIII CC-35 | Konza Prairie, First survey |
KonzaIII CC-40 | Konza Prairie, First survey |
KonzaIII GG-54 | Konza Prairie, First survey |
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