The prostigmatic mites including Heterostigmata (Acari: Trombidiformes) comprise one of the most myrmecophilous mite lineages. One of the well known heterostigmatic ant-associates genus is Petalomium (Pygmephoroidea: Neopygmephoridae). In an investigation on ant-associate mites in some parts of central and southern Iran, five species of the genus Petalomium Cross were collected from ants of the genera Camponotus, Lasius and Messor (Hymenoptera: Formicidae). One new species, P. olszanowskiisp. nov., is described and illustrated here. The other species include P. aleinikovae (Sevastianov, 1967), P. crinitusKhaustov and Trach, 2013, P. formicarum (Berlese, 1903), and P. gottrauxiMahunka, 1977. Except the latter, all species are new to arthropod fauna of Iran. In addition, P. aleinikovae is redescribed, and world distributions and host records of all the congeners are reviewed.