Life habit: lichenized, not lichenicolous Thallus: endolithic or reduced to beneath apothecia attached by medullary hyphae, occasionally chasmolithic with fertile areoles appearing rimose photobiont: primary one a chlorococcoid green alga, secondary one absent Ascomata: apothecial, broad to narrowly attached, or immersed in pits in the substrate, or stipitate disc: orange-brown or red-black (when wet) or black (dry), circular or irregular when distorted by compression, usually rough to very uneven, sometimes dividing to form new apothecia or producing an umbo from which a new apothecium regenerates from an old one, sometimes pruinose margin: lecideine, prominent, persistent or becoming excluded, smooth or rough, entire to crenulate and splitting true exciple: externally black or brown, carbonized or not, internally colored to hyaline epihymenium: yellow to golden or reddish to dark brown, conglutinate hymenium: hyaline to orange, I+ blue or red or both (the I reaction was too variable and was not used as being diagnostic); paraphyses: simple to sparsely branched, regularly septate, with end cells ±swollen, sometimes with a brown pigmented hood, usually conglutinated but loosening in K subhymenium: usually hyaline, indistinct hypothecium: hyaline to dark brown, thin or thick asci: cylindrical to clavate, unitunicate, thick-walled, strongly thickened at apex; outer wall coat I+ blue; tholus K/I-; polyspored ascospores: hyaline, simple, narrowly ellipsoid to globose, thin walled, generally 3-6 x 1-3.5 µm, usually lacking a distinct perispore Conidiomata: pycnidial, immersed in thallus or in small, ±multilocular verrucae; conidiogenous cells: subcylindrical, enteroblastic, acrogenous conidia: hyaline, simple, subglobose to ellipsoid Secondary metabolites: often lacking ; unidentified pigment ('Lecanora-red') in some apothecia Geography: cosmopolitan Substrate: on silicate or carbonaceous rocks, rarely on soil. Notes: Polysporina differs in having gyrose apothecia with a carbonized epihymenium. Polysporina has species with carbonized exciples but some species of Sarcogyne also have carbonized exciples. The multi-locus molecular work of Reeb et al. (2004) shows that the genus Acarospora is not monophyletic and that S. regularis may best be treated as a species of Acarospora. But morphologically S. clavus, and S. privigna appear to be distinct from Acarospora. The concept of Sarcogyne based on just lecideine apothecia (an important characteristic) is too narrow but other characteristics suggest that a revision of the genus and a systematic revision of Acarosporaceae will require careful molecular and morphological study of every species currently included in Sarcogyne. In this treatment species that are clearly related to the polyphyletic concept of Sarcogyne are artificially grouped in preparation for a revision. The genus is often said to have many specimens that do not fit established taxa. This is true, but just as important is the fact that the genus has been poorly collected with the result that existing taxa are not well known. Types for taxa described by Magnusson (1935), based mostly on specimens of Bouly de Lesdain, are missing. But based on our study of specimens from the Sonoran area and Magnusson's taxonomy, we believe these lost taxa, except for S. novomexicana, should be excluded from future consideration and treated as probable synonyms of recognized taxa as discussed in the notes. The color of apothecia when wet may be helpful for determining specimens, but this should not be over-stressed. The distinction between carbonized and non-carbonized exciples is relative. Rarely on usually unstable substrates, S. similis and S. regularis can produce visible thalli.