Malenchus truncatus
Knobloch, 1976
Holotype female: L = 0.40 mm; a = 23; b = 4.9; c = 6.3; V
= 69%; stylet = 11 um; CSE (CSE = Cuticular striae in esophageal
region) = 56; T/ABW = (Tail length divided by anal-body width) = 6.7
Allotype male: L = 0.39 mm; a = 24; b = 4.9; c = 5.1; T = 53;
stylet = 10.6 um; spicules = 16 um, gubernaculum = 5 um;
T/ABW = 7.0
Paratype females (8): L = 0.40 (0.38-0.42) mm; a = 21 (18-23);
b = 5.2 (4.7-5.3); c = 6.2 (5.2-7.2); V = 69% (67-70%); stylet = 10.5 (10.0-11.9)
um; CSE = 53 (49-56); T/ABW = 6.3 (5.9-7.2).
Paratype males (4): L = 0.40 (0.39-0.42) mm; a = 22 (19-24);
b = 4.9 (4.7-5.2); c = 5.3 (5.1-5.6); T = 55 (52-59); stylet = 11.0 (10.0-11.4)
um; spicules = 16 (15-16) um; gubernaculum = 5 um; T/ABW = 7.5 (6.8-7.9).
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
