Psilenchus hilarulus
deMan, 1921
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L = 0.9-1.3 mm; V = 50

Spear 17u-19u long, without knobs. Ovaries paired, outstretched. Tails typically elongate conoid to clavate terminus but some specimens have more cylindroid terminus.

Psilenchus hilarulus is immediately distinguished by its large size, clavate long tails, rounded unstriated lip region and position of amphid apertures.

(Description- Thorne, 1961)
1.1-1.5 mm; a = 33-38; b = 6.5-7.1; c = 8.0-8.5; V = 47
1.0-1.2 mm; a = 32-36; b = 6.0-6.8; c = 6.0-6.6; T = 42
Cuticle marked by striae which average about 1u apart near the head, slightly less on the body proper, and generally much finer on the tail.  Occasionally specimens occur on which the caudal striae are variable in width and sometimes extend completely to the terminus, as described by deMan.  Lateral fields marked by four incisures except near the head and on the tail, where they are reduced to two.  Deirids prominent, opposite nerve ring.  Phasmids easily seen, two or three body widths posterior to anus.  Tails elongate, tapering to the terminus, which varies from cylindrical to clavate.  Amphid apertures elongate, slitlike, located well below contour of lips.  From a face view the lateral sectors of the head are observed to be widened to make room for the broad, pouchlike amphidial chambers.  Three papillae observed on each of the four submedian head sectors, but none seen on the lateral ones.  Spear slender, devoid of basal knobs.  Dorsal esophageal gland opening into lumen of the esphagus at base of the spear.  Median bulb ovate with conspicuous valvular apparatus; posterior bulb pyriform with the usual three gland nuclei.  Excretory pore opposite nerve ring.  Cardia conoid, submerged in the anterior end of the intestine.
     Ovaries paired, outstretched.  An elongated spermatheca present in each uterus.  Spicula curved, tapering, cephalated, resting on a thin, troughlike gubernaculum.  Bursa crenate, rising near a point about opposite proximal ends of spicula and extending past anus a distance equal to about twice anal body diameter.  Male phasmids located near posterior ends of bursa.

This species is readily distinguished among the didelphic forms by the unstriated lip region, slender, knobless spear, and location of the amphid apertures.

Habitat and distribution:  Soil about roots of plants, bank of River Mark near Breda, Netherlands.  A rather common species in cultivated and virgin soil from the western and north central United States.  Nothing is known of its feeding habits.

DNA Sequences Obtained
Specimen: Collected:
KonzaVI EE-129 Konza Prairie, First survey