Fatemeh Khakbaz - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Farshad Gharibzadeh - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Mohammad Reza Atighi - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Majid Pedram - Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. Iranian Research Institute of Plant Protection, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran.

Ditylenchus azarbaijanensis n. sp. is described and illustrated based upon morphological and morphometric characters. The new species is mainly characterized by having six lines in the lateral field, rudimentary postuterine sac (PUS) ca. ۰.۲ vulval body width long, anteriorly inclined vagina and conical female tail with a pointed terminus, ۴۸-۷۰ µm long (c = ۱۵-۲۱, cʹ = ۲.۴-۳.۷). It is further characterized by having fine stylet ۷.۵-۱۰.۰ µm long with small knobs, small pyriform pharyngeal bulb offset from the intestine, and males with ۲۶.۵-۳۱.۰ µm long spicules. By having a rudimentary PUS, the new species is morphologically compared with three closely related species, namely Ditylenchus apus, D. deiridus and D. khani. Moreover, morphological differences of the new species with eight similar species of the genus, namely D. arachis, D. convallarie, D. dauniae, D. medicaginis, D. silvaticus, D. tenuidens, D. valveus, and D. virtudesae are presented. The status of the rudimentary or absent PUS of D. deiridus and the new species is also discussed.

Diptenchus, Ditylenchus deiridus, D. khani, morphology, morphometric data, new species, taxonomy