Citrus are one of the most important tropical and subtropical crops in the world that widely consumed worldwide as juice or fresh fruit, providing important sources of vitamin C. A wide range of plant-parasitic nematodes have been associated with the citrus rhizosphere. In the present research, plant-parasitic nematodes associated with citrus orchards were studied in Khuzestan province. Based on morphological and morphometric characters and using valid keys such as Geraert (2008) for identification of Basiria Siddiqi, 1959 species, a population of Basiria graminophila Siddiqi (1959) was isolated and identified from the rhizosphere of citrus in the vicinity of Shush, Dezful and Baghmalek cities. This population can be recognized by having body almost straight to slightly ventrally curve, lateral field with four distinct incisures, lip region smooth, amphidial apertures oblique and slit-like, stylet straight, 9-12.5 μm long, with rounded basal knobs, median bulb oval, basal bulb pyriform, spermatheca elongated, non-offset, with rounded sperm, post-vulval uterine sac less than of corresponding body width long, tail usually long, 84-120 μm long, with finely rounded to slightly pointed terminus, spicules 15-17.5 μm long. For molecular study, DNA was extracted. Sequence of the D2-D3 expansion segments of 28S rDNA gene was used for molecular phylogenetic analysis. Nblast result showed most identity of the studied population with species of Basiria sp. 1 and Basiria sp. 3 from Iran deposited in GenBank (JQ004999 and JQ004998). The phylogenetic relationships between this population of B. graminophila with other species of Basiria genus and representatives of Tylenchidae were studied. Aphelenchoides fragaria (DQ328683) was selected as outgroup. Phylogenetic analysis was performed using the Maximum Likelihood method and software Mega 6. Result showed that this population places together with other populations of Basiria sp. with high support (98%) in a same clade.