Domene (Lathromene) lusitanica n. sp. from Sicó karstic massif in Portugal is described and compared with other species of the subgenus, representing the first hypogean rove beetle from mainland Portugal. A comparison between Domene lusitanica n. sp. and the other species of the Iberian endemic subgenus Lathromene is made using diagnostic characters. An identification key for the males of Lathromene species is presented, and biogeographical and ecological comments are also included. The species of Domene known from the Iberian Peninsula are listed and their distributions are mapped.