Four new nematode species are described: Theristus quadripapillatus, sp. nov., distinguished from all known species of the genus in possessing four genital supplements, in the structure and shape of the gubernaculum, and in possessing a glandular tube parallel with the anterior testis and opening into the vesicula seminalis; Acanthopharynx distechei, sp. nov., characterized by its head shape with smooth helmet bearing 24 subcephalic setae, by the elongated loop-shaped amphids, and in males by possessing only one pre-anal papilla; Ptycholaimellus lizardiensis, sp. nov., characterized in males by the shape of the gubernaculum with two lateral pieces with an enlarged, dentated distal end, and by the presence of a small pre-anal papilla; and Paracanthonchus parahartogi, sp. nov., characterized by having an outer circle of 10 minute setose sense organs, by having a very small tooth, and in males by the shape of the copulatory apparatus and the six pre-anal supplements.
For four known species additional information is given: Paracomesoma dubium (Eilipjev, 1918) Stekhoven, 1950; Actinonema longicaudatum (Steiner, 1918) Wieser, 1954 ; Halichoanolaimus quattuordecimpapillata Chitwood, 1951; and Bathylaimus australis Cobb, 1894.