In a survey on insect-associate heterostigmatic mites in northern forests of Iran, six species of the genus Petalomium Cross, 1965 (Acari: Pygmephoroidea: Neopygmephoridae) were collected from different ants (Hymenoptera: Formicidae). One species, P. mazandaranicum Abbasi-Moqadam and Hajiqanbar sp. nov., is new to science and described here. Other species, all new to mite fauna of Iran, are as follows: P. fimbrisetum Ebermann & Rack, 1982, P. heterotrichus Mahunka, 1970 (new for Asian fauna), P. rarus (Sevastianov, 1967), P. sawtschuki (Sevastianov, 1967), and P. scyphicum (Sevastianov, 1967). Petalomium heterotrichus is redescribed, three new ant hosts are recorded, and world distributions of all mites are reviewed.