An annotated list of Iranian digger wasps of the genus Tachysphex Kohl, 1883 (Hymenoptera, Apoidea, Crabronidae) is presented based on the material collected in the southern part of the country and on data published from the period 1933-March 2020 (87 years). In all, 46 species of eight species-groups are documented (T. persa has two subspecies: T. persa persa Gussakovskij, 1933 and T. persa nigripes Pulawski, 1967). Of the eight species-groups, the pompiliformis species-group (17 species) and the panzer species-group (11 species) are the most species-rich, whereas the brevipennis species-group is represented by only one species. The following three species are newly recorded from Iran, all from Fars Province: T. helveticus Kohl, 1885, T. melas Kohl, 1898 and T. palopterus (Dahlbom, 1845). About 19 (41.30%) of the species included here are exclusively Palaearctic, whereas 15 species (32.61%) have wider distributions in the Afrotropical, Palaearctic and Oriental zoogeographic regions. Neighboring countries have many species that overlap with the Iranian Tachysphex fauna; Iran shares 36 species (78.20%) with Turkey, 28 species (60.86%) with Turkmenistan and 18 species (39.13%) with United Arab Emirates.
