Three new vagrant species of eriophyoid mites living on the lower leaf surface of Lippia alba (Mill.) N. E. Brown (Verbenaceae) in the Northeast and Center West Brazil, are described and illustrated. They are: Paraphytoptus serenus sp. nov. and Tegoprionus alobus sp. nov. (both from family Eriophyidae) and Rhynacus lippius sp. nov. (Diptilomiopidae). Detailed anatomy of internal genitalia of the representatives of the three eriophyoid genera (Rhynacus, Paraphytoptus and Tegoprionus) was studied and described for the first time. A new, previously neglected genital structure of eriophyoids, the thorn-like spermathecal process, has been discovered with the aid of confocal laser scanning microscopy. Preliminary analysis indicates that this structure is common for many eriophyid and diptilomiopid species, however it is absent in phytoptid mites. The hypothesis that presence/absence of this process separate contemporary families of Eriophyoidea (Phytoptidae and Eriophyidae Diptilomiopidae) needs further testing.