On occurrence of Paratylenchus labiosus Anderson & Kimpinski, 1977 (Nematoda: Tylenchulidae) in Iran, with discussion on the validity of the species

During a survey on the identification of plant-parasitic nematodes associated with walnut in Sanandej region (Kurdistan province, western Iran), a population of Paratylenchus labiosus was collected and identified morphologically. Description, illustrations and morphometrics of the species are given and comparisons are made between it and some related species. P. labiosus comes more close to three species namely P. similis, P. tateae and P. italiensis in having certain diagnostic characters such as short stylet less than 18 µm long, concave-conoid head with prominent submedian lobes and tail ending to an acute to finely rounded terminus. However, P. labiosus differs from them in having a spermatheca full of sperm cells and presence of males. Different modes of reproduction (parthenogenesis or amphimixis) may be observed in different populations of some species in this genus, but somewhat unique reproduction behavior of P. labiosus could be considered as a diagnostic character for separation of it from the three closely related species.