Plectus parvus
Bastian, 1865
Measurements (from Andrassy, 1985)
L = 0.46-0.49; a = 18-24; b = 3.5-3.7; c = 9-10; V = 50-54
(Bastian, 1865) L = 0.54 mm; a = 21; b = 3; c = 10.6;
V = 50
(Maggenti, 1961) L = 0.42-0.51 mm; a = 17-22; b = 3.4-4.0; c
= 7.9-10.4; V = 49-53
L = 0.48 mm; a = 22; b = 3.7; c = 8.2; spicules = 19/13 um
(Zullini, 1982) L = 0.41-0.57 mm; a =
17-27; b = 3.4-4.3; c = 8.5-12; V = 48-55
Description (from Andrassy, 1985)
Body small. Cuticle thin, 0.7-0.8 um,
annulation hardly discernible on major part of body. Lateral field
1/6 of body diameter, with two alae.
Head narrow, not set off, 6.5-7 um wide,
lips hardly separate. Body on proximal end of oesophagus 2.5-3 times
as wide as head. Cephalic setae thin, directed outward. Amphids
2.5 um wide, 8-10 um behind head, somewhat posterior to mid-stoma.
Stoma 15-17 um long, 2.3-2.5 times head diameter,
1/8 - 1/9 of oesophagus length. Oesophagus 128-134 um long,
bulbus oblong, cardial process thick. Excretory opening 75-78 um
from anterior extremity, in 57-66% of oesophagus length. Rectum as
long as anal diameter.
Vagina with two muscle circles. Each gonad
2.4-3 times as long as body width, 10-11% of body length. One egg:
43 X 18 um. Distance between vulva and anus 3.5-3.7 times
as long as tail. Tail 46-50 um long, 4-4.8 times anal body
diameter, 10-11% of body length, hardly bent ventrally, almost cylindrical.
Spur in the last fourth of tail length.
The male was described by Maggenti (1961).
Spicules asymmetrical. No preanal tubular organs.
Description (from Thorne, 1929)
The striae are fine and are interrupted on the lateral
fields by two distinct wings. The front ovary is on the right, the
rear on the left, side of the body. The eggs are huge and at times
the ovaries are crowded until the reflexed portion passes the vulva.
This active little species is one of the most common
nemas found in the mountain soils. About twenty specimens in this
collection.
Measurements (from Mulk & Coomans, 1978)
L = 0.44-0.51 mm; a = 16.6-25.9; b = 3.4-3.8; c = 8.1-10; V = 49-57;
stoma = 14-17 um
Description (from Mulk & Coomans, 1978)
Female: body almost straight to slightly
arcuate upon fixation; regularly tapering towards extremities, more posteriorly
than anteriorly. Cuticle marked with transverse striae. Body
annules almost of equal width except slightly wider on middle of tail.
Two longitudinal alae interrupt transverse striae on either side, lateral
field occupying one-eight to one-sixth of body near middle.
Lip region truncate, 3.0-3.5 times broader than
high, continuous with body; lips low, anteriorly rounded. Four, slender
cephalic setae 3-4 um long i.e. about 0.35-0.45 times width of lip
region; originating 2-3 body annules behind lip region, usually diverging
peripherally. Stoma about 2.1-2.3 times as long as the lip region
is wide. Cheilostome obscure. Prostome one-fourth to one-third
the length of mesometastome. Amphid apertures almost circular, 1.5-2.0
um
wide i.e. about one-sixth of body diameter at their lever, located about
halfway the meso-metastome, at 9-11 um from anterior extremity.
Excretory pore 70-80 um from anterior extremity, 62-65% of the total
oesophageal length. Nerve ring slightly above level of excretory
pore. Cervical papillae setiform, situated between longitudinal alae,
3-6 annules posterior to the level of excretory pore. Endbulb of
oesophagus almost oval, provided with moderately sclerotized denticulated
valves, slightly anterior to middle of bulb. Cardia well developed,
one-third to half the body-width long at its level. Intestine filled
with small granules. Rectum about one anal body-width long.
Vulva slit-like, elevated with prominent lips; vagina
extending inward about one-fourth to one-third of the body-width.
Ovaries reflexed, anterior on right and posterior on left side of intestine.
Eggs 42-48 um X 17-20 um. Tail arcuate, narrow, regularly
tapering; about four and a half anal body-widths long; bearing two subdorsal
and one subventral caudal setae on each side, left subdorsal one more posterior
than right subdorsal. Spinneret 1.0-1.5 um long.
Male: not found
DNA Sequences Obtained
