Three new corticolous Arthoniaceae are described from the Chapada do Araripe, an isolated table mountain in the state of Ceará, in NE Brazil. Arthonia stipitata, lichenicolous on unidentified sorediate crusts, with red, tiny, stipitate apothecia, 3-septate ascospores, 10–12×3·0–3·5 µm. Stirtonia lucida with rather small ascigerous areas, lichexanthone and zeorin in the thallus, globose asci, ascospores 8 per ascus, ellipsoid, 17–19×8–10 µm, with occasionally some longitudinal septa. Stirtonia ochracea with rather small ochraceous ascigerous areas, thallus without secondary metabolites, ascospores 8 per ascus, (7–)9(–11)-septate, 47–55×14–20 µm. These species were found during a study aiming at an inventory of the lichen biodiversity of the Cerrado forests in the area, and were not found during earlier ecological studies in the Caatinga forests in the same area. Stirtonia lucida is the first species assigned to this genus which occasionally has some longitudinal septa in the ascospores. Such specimens might be confused with Cryptothecia species.