Aphelenchoidesiranicusn. sp. is described and illustrated from bark samples of an oak tree (Quercussp.) in West Azerbaijan province, north-western Iran. The new species is characterised by body length of 350 (330-383) μm in females and 343 (323-370) μm in males, lip region set off from body contour, lateral fields with three lines, stylet 8 (7-9) μm long with small basal swellings, excretory pore 59 (56-62) μm from anterior end, hemizonid invisible, pharyngeal glands overlapping intestine dorsally and extending for 48 (41-54) μm, female tail subcylindrical with many tiny finger-like appendages at the tip, and male with aphelenchoid type spicules 17.6 (17-18) μm long. The new species comes close to nine known species of the genus namely:A. brevicaudatus,A. cibolensis,A. conimucronatus,A. editocaputis,A. montanus,A. pusillus,A. rarus,A. sphaerocephalusandA. vaughani, but differs from them by the number of incisures in the lateral field, shape of tail mucron, stylet length, size of spicules and length of post-vulval uterine sac. Additionally, this species is characterised molecularly and phylogenetically by sequences of the D2-D3 expansion segments of the 28S and partial 18S rRNA genes that are unique in relation to the sequences deposited in GenBank.