A new and four known species of the genus Diphtherophora-D. geraerti sp. n., D. caudata, D. obesa, D. perplexans and D. tenera-were collected and identified from different plants and localities in Iran. Morphological and morphometric characters of Diphtherophora geraerti sp. n. are compared with those of closely-related species, including D. siddiqii, D. brevicollis, D. lata, D. obesa, D. citri, D. vasilevi and D. vitoshae. Females of the new species have a head continuous with the body contour, spear 11-14 µm in length, rod-shaped spermatozoa and conical tail with bluntly rounded to hemispherical terminus. Males have two ventromedian neck papillae located 22-25 and 52-60 µm from the anterior end, and two ventromedian supplements at 11-13 and 75-80 µm anterior from cloacal aperture, respectively. All Diphtherophora species recovered as part of the present study are new records for the Iranian nematode fauna. Finally, a diagnostic compendium is given, to assist with species identification in the genus.
Keywords: Nematoda, Morphology, new species, new record, taxonomy.