Rev 02/21/2024
Type species of the genus: Nygolaimus brachyuris (de Man, 1880) Thorne, 1930
Body length 1.0-3.5 mm
Cuticle smooth with finely-striated subcuticle.
Labial region offset from body contour, lips separated, not fused.
Stoma a simple eversible tube with slightly sclerotized walls.
Armed with a spear-like mural tooth, with no guiding ring.
Basal section of esophagus covered by a thin sheath.
Three cardiac glands between the base of the esophagus and the intestine.
Tail similar in both sexes, usually short andconvex-conoid to conoid.
Ref: Andrassy, 2009
Males:
Males without gubernaculum (although Thorne (1930) reported a gubernaculum, sometimes difficult to see, posterior to the spicules).
Male without or with weakly-developed ventomedian supplements.
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Mural tooth and eversible stoma of Nygolaimus sp. Subdorsal view (left), Lateral view (right)
Drawings from Coomans (1963)
Females:
Soil and aquatic environments. More prevalent in coarse textured soils and most abundant in the upper 30 cm of soils in cultivated fields (Thorne, 1930).
Classified as predators (Yeates et al., 1993).
Observed to feed on nematodes in tissue culture (Wood, 1973).
In a classic study of nematodes of the genus Nygolaimus in sugarbeet fields of the western USA, Thorne (1930) reported that although species of Nygolaimus were found in close proximity to white females of Heterodera schachtii, he was unable to find traces of nematode body parts within the predators. However, feeding on oligochaets was observed and the intestine of the nematodes often contained oligochaete setae and cuticle.
Thorne (1930) pointed out that nygolaims are equipped with a protrusible mural tooth rather thatn an axial odontostyle. The tooth is closed at the tip and may be solid throughout. Food is not channeled through the tooth. In feeding, the nygolaims apparently located the oligochaete by touch and then pressed the lips tightly against the body of the prey and the tooth is driven into the body. The body of the victim is cut by a dorsal to ventral slash of the tooth. The tooth is then withdrawn and the body contents of the prey sucked through the oral aperture.
Thorne (1930) reported that native species disappear when land is cleared and cultivated and that different species inhabited cultiveted and undisturbed soils in the same region: "The distribution of the various species in a locality is usually quite definite. Some are found in the cultivated valley soils, while others appear only in collections from the mountains. The largest populations usually occur in the cultivated fields. In no instance has the same species been found inhabiting both cultivated and virgin soil. The native species disappear when the land is cleared and irrigated, and in their place are found species whose origin is problematical. Near Salem, Utah, Nygolaimus tennis and N. vulgaris are numerous in cultivated fields, while in virgin soil only a few rods distant N. brachyurus and N.. bisexualis are the species found."
Andrassy, I. 2009. Free-living Nematodes of Hungary III. Hungarian Natural History Museum, Budapest. 608p.
Coomans, A. 1963. Stoma structure in members of the Dorylaimina. Nematologica 9:587-601.
Thorne, G. 1930. Predacious nemas of the genus Nygolaimus and a new genus, Sectonema. Journal of Agricultural Reaearch 41:445-466.
Wood, F.H. 1973. Nematode feeding relationships: Feeding relationships of soil-dwelling nematodes. Soil Riol. Biochem. 5: 593-601.
Yeates, G.W., T. Bongers, R. G. M. De Goede, D. W. Freckman, and S. S. Georgieva. 1993. Feeding habits in soil nematode families and genera—An outline for soil ecologists. Journal of Nematology 25:315-331.