In a study, 13 known species of Ditylenchus Filipjev, 1936 were collected during 20132017 mainly in the southern provinces of Iran, and the variability of their morphological and morphometric characteristics was investigated. The results showed that the number of lateral lines, V and V indices, stylet and spicule length, whose coefficient of variation was less than 10%, were more stable than the other characters. The effects of different temperatures and food sources, including several plants, fungi and carrot disc on the taxonomic characters of three populations of Ditylenchus destructor, two populations of D. dipsaci, and one population of D. myceliophagus were studied. The results showed that indices V, V and MB were more stable than the others. The indices were more affected by food source than by temperature. In addition, the calculation of the correlation between some morphometric indices showed that the distances between the anterior end and vulva, and the anterior end and anus were significantly correlated with body length in all species and populations studied.