Plectus parvus
Bastian, 1865

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George Washington Memorial Parkway

Konza Prairie
Long's Peak, Colorado

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
Specimen: Collected:
KonzaVIII AA-150 Konza Prairie, First survey
KonzaIV BD-142 Konza Prairie, First survey