Cruentotrema is a genus of corticolous (bark-dwelling) lichens in the family Graphidaceae. It has seven species.
The genus was circumscribed in 2012 by Rivas Plata, Papong, H. Thorsten Lumbsch, and Robert Lücking, with Cruentotrema cruentatum assigned as the type species. This enigmatic lichen had previously been described three times under different names: as Stictis cruentata, as Arthothelium puniceum, and as Thelotrema rhododiscum . Molecular phylogenetics revealed its true affinities in the subfamily Fissurinoideae of the family Graphidaceae. The genus name combines the species epithet of the type species with the suffix -trema. Three species were included in the original circumscription of the genus.
Characteristics of the genus include rounded, ascomata, a (blackened), the absence of a columella, and inamyloid asci and . The of Cruentotrema lichens number eight per ascus, and are colourless and ellipsoid with thick septa and diamond-shaped chambers of the Trypethelium-type.
, Species Fungorum (in the Catalogue of Life) accepts seven species of Cruentotrema: