Life habit: lichenized Thallus: crustose, uniform, orbicular to spreading, smooth to verrucose-areolate or granular; weakly corticate; attached to substrate by medullary hyphae; prothallus: absent or distinct, white, fibrous, radiating surface: white, gray or dull greenish gray; sorediate or not cortex: composed of agglutinate, thin walled hyphae photobiont: primary one a trebouxioid green alga, secondary one absent Ascomata: apothecial, usually sessile, sometimes adnate or immersed, lecanorine or aspicilioid, round or somewhat irregular disc: red or pinkish red to orange, with or without pruina margin: thalline, usually well developed, concolorous with thallus, persistent, entire or crenulate, or becoming excluded exciple: if evident, thin and red epihymenium: K+ red (magenta to purple) or hyaline, the red pigment hardly soluble in acetone hymenium: hyaline, I+ blue; paraphyses: strongly branched and reticulate, with a gelatinous outer wall, with apices not or only slightly swollen; hypothecium: hyaline or pale asci: clavate, unitunicate, thin walled, Haematomma-type, the tholus I+ blue, with ocular chamber and narrow, faintly I+ blue axial mass, 4-8-spored ascospores: hyaline, straight or spirally curved within ascus, transversely 3-many septate (rarely also with longitudinal septa), fusiform to broadly acicular, thin walled Conidiomata: pycnidial, immersed; ostiole: red or flesh colored, K+ magenta, or hyaline (never green); conidiophores: type V of Vobis (1980), little branched or unbranched; conidiogenous cells: terminal and intercalary, ampulliform enteroblastic conidia: simple, hyaline, type I or II (Rogers and Hafellner 1988), pleurogenously formed, curved-filiform or straight and bacilliform Secondary metabolites: apothecia with anthraquinones; thallus with ß-orcinol depsides and depsidones, orcinol depsides, xanthones, usnic acids and dibenzofurans, terpenoids, aliphatic acids Substrate: on bark or rock, rarely wood Geography: northern holarctic distribution for the H. ochroleucum complex, but tropical to subtropical for the H. puniceum complex. Notes: Haematomma is easily recognized by the combination of lecanoroid, bright red to orange apothecia (the apothecial pigment is hardly soluble in acetone) and hyaline, multiseptate spores. Ophioparma differs especially in its red apothecial pigment that is easily soluble in acetone and K+ blue, its thick exciple, its asci lacking an axial mass, its pycnidia have a blue-green pigment, and its conidiophores being type VI of Vobis (1980). Loxospora differs in containing thamnolic acid (K+ bright yellow, P+ orange), having brownish discs, asci with a very wide axial mass, and ascospores spirally twisted in the asci and long remaining non-septate. Both other genera have wider, rarely branched (but +anastomosed) paraphyses without gelatinized walls. Although sorediate Haematomma species are known, none are known in the Sonoran region. Thus, sorediate or subsorediate thalli with red apothecia in our area are likely to be a different genus (e.g. Omphioparma or Pyrrhospora).