Female: Body usually straight or with slight
ventral curve posterior to vulva. Width of cuticular striae about
1.5 um in mid-body. Fifty-six transverse cuticular striae
in esophageal region. Lateral field with two crenate incisures; field
occupies about 1/6 body width and extends from midway between stylet knobs
and metacorpus to near middle of tail Cephalic region continuous
with 5-6 transverse striae; no cephalic sclerotization observed.
Anterior end appears
truncate. Stylet length 11 um with knob slanting posteriorly.
Metacorpus ovoid with valve; basal bulb pyriform. Excretory pore
5-6 um poterior from basal bulb. Hemizonid not seen.
Vagina thick-walled. In some specimens, vulva
opening has more conspicous vulval flaps than observed in other species.
Poterior uterine branch slightly more than half the corresponding body
width. Ovary single, outstretched; spematheca ovoid, filled with
spermatozoa. Tail tapered
to acute terminus, finely striated to tip. Anus obscure.
Tail 1.1 times longer than vulva-anus distance, about 6-7 times anal body
width. No phasmids observed.
Male: General morphology similar to that of female. Cephalic region narrower than in female. Testis single, outstretched; spicules and gubernaculum as illustrated. Caudal alae adanal, finely crenate, typical of genus.
Diagnosis: Malenchus truncatus differs from all known species in the genus by the truncate anterior end. It is distinguished from A. andrassyi by continuous cephalic region with 5-6 transverse striae, fewer transverse cuticular striae in esophageal region, more posterior vulva, shorter tail with acute terminus. M. andrassyi has contracted cephalic region, no cephalic striae, eighty cuticular striae in esophageal region, vulva at 55-64%, tail length 80-102 um, and, according to drawings, 10-11 times anal body width with rounded terminus. Male of M. truncatus has longer stylet; shorter, less filiform tail. M. andrassyi male stylet length 8-9 um, filiform tail 12-13 times anal body width. From M. machadoi, the new species differs in size, cephalic region shape, and tail shape. M. machadoi is 0.52-0.56 mm in length with definitely contracted and rounded cephalic region. tail 8.5-9.5 times anal body width with a more acute terminus.
Holotype: Female collected December 1974 by John Davenport. Slide T-249t deposited with the USDA Nematology Collection at Beltsville, Maryland, USA.
Allotype: Male. Slide T-250t. Data same as holotype.
Paratypes, females and males: Slide T-1745p, 1 female. Slide T-1813p, 1 male. Data same as holotype. All other paratype slides in the Nematology Collection in Entomology Department, Michigan State University, E. Lansing, Michigan, USA.
Type habitat and locality: Soil under moss and leaf litter in low, bog-like area near woods in Michigan State University Water Quality Management Project site in East Lansing, Ingham County, Michigan, USA.
(Description- Knobloch, 1976)
DNA Sequences Obtained
|RMNP-DFF-12-92||Long's Peak, Rocky Mountain Nat'l Park|
|RMNP-DFF-12-96||Long's Peak, Rocky Mountain Nat'l Park|