Paratylenchinae: morphology of some known species and descriptions of Gracilacus bilineata sp.n. and G. vera sp.n. (Nematoda: Tylenchulidae).

Ten species of Paratylenchus and six of Gracilacus are discussed. P. italiensis, P. tateae and P. labiosus are synonymized with P. similis. Measurements of specimens from various populations are presented, and previously published morphometric data compiled in tables to characterise known limits of species variation. The significance of morphology of males and juveniles in identification of these nematodes is shown in descriptions of various species. It is demonstrated that in G. macrodora the third stage juvenile lacks a stylet, while the fourth stage juvenile has a well developed stylet and oesophagus and apparently feeds. G. bilineata sp. n. from Taiwan has only two incisures, lips not protruding, stylet 46 (43-50) μm, V = 73-78, no vulval flaps, and males with very thin stylet. G. vera sp. n. from Mexico is characterized by having sublateral lips projected anteriorly, four incisures, stylet 78 (66-86) μm, V = 76-79, small vulval flaps, and males without stylets.