Mostly small to medium sized nematodes, seldom exceeding 3-4 mm. The cuticle is ornamented by annuli that are sometimes transversed by longitudinal striae; the cuticle may be punctated. The labia may be well developed but hexaradiate symmetry is almost always evident. The full complement of cephalic sensilla is often present, especially on males. In derived taxa the inner circle of six sensilla may be lacking. In the external circle of 10 sensilla the externolaterals are ventrolateral on the lateral labia. The amphids, when labia are evident, are located dorsolaterally on the lateral lips and the aperatures are porelike, small ovals, silts, or clefts. In some larval forms, particularly dauerlarvae, the amphids may be postlabial. The variable stoma is primarily composed of cheilostomal tissue and is most often armed. Except for rare instances, moveable stomatal armature in the form of large teeth, opposable fossores, or axial spears is limited to the subclass. The esophagus has a muscular corpus divided into an almost cylindrical procorpus and a muscular, almost always valved, meta corpus followed by an isthmus and a glandular postcorpus. A valve is never present in the postcorporal bulb. Females have one or two ovaries and males have one testis. Males have paired spicules but may or may not have a gubernaculum or caudal alae (Maggenti, 1991).
Maggenti, A.R. 1991. Nemata: higher classification. In: Manual
of Agricultural Nematology, W.R. Nickle [ed.]. Marcel
Dekker, Inc., New York.
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