The morphology and morphometric characteristics of a Longidorus population recovered from a wheat-potato field in Hamadan province, western Iran, fit well with those given for two species, L. proximus and L. israelensis. The Iranian population was characterized by 5.6 to 8.6-mmlong females having a 17 to 21-µm-wide lip region separated from the rest of the body by a shallow depression, pocket-shaped amphidial fovea with a simple base and a ventral enlargement, a guiding ring at 31 to 40 µm distance from the anterior end, 108 to 127-µm-long odontostyle, 58 to 64-µm-long odontophore, 101 to 129-µm-long pharyngeal bulb with remarkably larger dorsal gland nucleus (at 49 to 53% of the bulb length) and two smaller ventrosublateral nuclei (at 66 to 76% of the pharyngeal bulb length), four juvenile developmental stages, and a rare male. The morphological and molecular data corroborated its assignment to the species L. proximus. In molecular phylogenetic analyses using partial LSU rDNA D2-D3 sequences, the presently studied Iranian population and previously sequenced isolates of L. proximus formed a clade with L. cretensis, L. iranicus, L. pseudoelongatus, and L. closelongatus, all except L. pseudoelongatus with no available data, having the similar pharyngeal gland nuclei size and arrangement. In internal transcribed spacer 1 (ITS1) phylogeny, it formed a clade with L. sturhani and four aforementioned species. The characters delimiting the two species L. proximus and L. israelensis were discussed and a new synonymy was proposed.