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DescriptionLife habit: lichenized; Thallus: crustose, continuous, warted-areolate or subsquamulose; surface: soredia absent or present; cortex: present or absent; photobiont: primary one a trebouxioid alga 7-13 µm in diam., secondary one absent; Apothecia: mostly sessile and constricted at the base, sometimes flexuose or tuberculate; disc: pale beige to reddish brown, or blue-gray to black in some species; margin: without algal cells, usually weakly prominent, soon becoming excluded; exciple, hypothecium and subhymenium: composed of strongly gelatinized hyphae, hyaline, weakly brown or bluish green; hymenium: hyaline or bluish green, strongly amyloid; upper part (epihymenium): usually unpigmented, with an amorphous bluish green pigment or brown granules in some species; paraphyses: weakly branched and anastomosing, strongly conglutinate, septate, usually not distinctly thickened apically and without distinct pigmentation; asci: clavate, 8-spored, Biatora-type with an ILugol+ blue tholus and a lighter blue axial body surrounded by a darker blue zone; ascospores: hyaline, simple to 3(-5)-septate, needle-shaped, narrowly to broadly ellipsoid or ovoid, smooth-walled; Conidiomata: pycnidial, (semi-)immersed, mostly of the same color as the apothecia; conidia: simple, bacilliform, rarely broadly filiform or ellipsoid, hyaline; Secondary metabolites: depsides, depsidones, xanthones or usnic acid, some species without secondary metabolites; Geography: in temperate, boreal and arctic regions of the Northern Hemisphere.; Notes: The circumscription of Biatora has changed considerably during recent years. Once it comprised almost all species of Lecidea s. lat. with a biatorine exciple (e.g. see names in Fink ), it was recently reduced to a small group around B. vernalis characterised by a crustose thallus, biatorine apothecia without a distinct margin, +unbranched, unpigmented paraphyses, asci of the Biatora-type, and hyaline, narrowly to broadly ellipsoid ascospores. Only few species, such as B. meiocarpa, have apically thickened paraphyses. Likewise, a distinct epihymenium is only developed in few species. Hymenium, hypothecium and exciple are composed of gelatinised, strongly conglutinate hyphae. The excipular hyphae are +parallel and have cylindrical to broadly ellipsoid lumina. The closely related Mycobilimbia is mainly distinguished on account of a different ascocarp ontogeny. Biatora species can also be confused with species from the Lecanora symmicta group (with narrow excipular hyphae and a distinct epipsamma) or species from the Lecidea erythrophaea group (with apically thickened paraphyses with brown apical cells). Within the Sonoran Desert Region, the whole genus is only known from a single, relatively moist, high montane locality.