Comments on some known species of the genus Tylenchus and description of Tylenchus stachys sp. n. (Nematoda:Tylenchidae).

Variability of Tylenchus arcuatus, T. elegans (n. syn. T. ritae and T. capitatus), T. davainei (n. syn. T. martini) and T. rex are discussed. T. neominimus and T. parangalici are considered species inquirendae. Stylet length, areolation of lateral field, ratio "a" and body shape upon relaxation are reliable characters for Tylenchus species differentiation. Tylenchus stachys sp. n., from Australia, is characterized by stylet 14.5-16.5 μm, outer bands of lateral field areolated on entire body, body thin and slightly arcuate.