Rotylenchus arasbaranensisn. sp., a new monosexual species is described and illustrated based on morphological, morphometric and molecular studies. The new species is characterised by having an offset and hemispherical lip region with 5-6 annuli, 32-36 μm long stylet, vulva located at 43.9-59.2% with a single epiptygma and rounded tail, rarely bilobed, with 6-8 annuli. The speciesR. striaticepsand the male ofR. buxophilusare reported for the first time from Iran andR. fragaricusis reported and studied for the second time after its original description. The results of the phylogenetic analyses based on the sequences of the D2-D3 expansion region of the 28S, ITS1-rRNA and the partial 18S rRNA genes were provided for the studied species, confirming their differences from each other and determining the position of them and their relationships with closely related taxa. Also, the validity ofPlesiorotylenchusis discussed on the basis of molecular data and its synonymisation (with only one sequence) withRotylenchusis accepted.