Biatora Fr.:Fr.
Type : Biatora vernalis (L.) Fr.
Description : Thallus crustose, continuous, verrucose-areolate to subsquamulose, with or without soredia, upper cortex present or absent. Photobiont green, trebouxioid. Ascomata apothecia, sessile, constricted at base, sometimes becoming tuberculate, exciple without photobiont cells, of strongly gelatinised hyphae, hyaline, pale-brown or bluish green; margins often excluded. Disc pale-beige to reddish brown or blue-grey, matt, epruinose. Epithecium unpigmented, or with amorphous bluish green pigments or brownish granules in some species. Hymenium colour to bluish green, strongly I+ blue. Subhymenium and hypothecium of strongly gelatinised hyphae, colourless, pale-brown to bluish green. Hamathecium of paraphyses, weakly branched and anastomosing, strongly congflutinate, septate, without distinct apical thickening or pigmentation. Asci clavate, 8-spored, Biatora -type, with an I+ blue tholus and a paler blue axial body surrounded by a darker blue zone. Ascospores colourless, simple to 3(–5)-septate, acicular, narrowly to broadly ellipsoidal or ovoid, smooth-walled. Conidiomata pycnidia, semi-immersed. Conidia simple, bacillar, rarely broadly filiform or ellipsoidal, colourless. Depsides, depsidones, xanthones or usnic acid present or absent.
Biatora is widely distributed in temperate and arctic regions with c. 50 species known worldwide (Printzen 2004). It is included in the family Ramalinaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). European and North American species are discussed by Printzen (1995, 2000, 2004), Printzen & Tønsberg (1999, 2003, 2004), Printzen & Palice (1999) and Printzen et al. (1998, 1999, 2001). In its current circumscription Biatora accommodates crustose corticolous or muscicolous lichens having a green photobiont, biatorine apothecia, asci of Biatora -type, colourless, simple to 3-septate ascospores, and bacillar conidia. Biatora differs from Bacidia in having a proper exciple of moderately non-anastomosing hyphae running parallel to each other. The cell lumina are narrowly cylindrical, evenly thickened and do not widen appreciably near the margin of the proper exciple. The walls are moderately thick (as in Bacidina, but thinner than in Bacidina). Also, Biatora differs in having a chondroid hypothecium, milky-white when dry and water-resistant; an often weak and diffuse pigmentation of the apothecia; simple to 3-septate and ±ellipsoidal ascospores without a perispore; and ampulliform conidiogenous cells. Bacidina and Biatora do not differ consistently in the composition of the apical tholus (Ekman 1996a). Several corticolous taxa referred to Lecidea s. lat. (q.v.) may well be best placed in Biatora, but they are maintained in Lecidea pro. tem., until their affinities to Northern Hemisphere taxa are properly studied. They have no place in Lecidea s. str. (q.v.), but their exact generic placement is yet to be accurately determined. The genus appears to be largely absent from the Southern Hemisphere, though this may reflect the paucity of collections. One species is recorded from New Zealand, but the genus is very poorly known and collected here. Taxa described as Lecidea s. lat. (q.v.) may well be accommodated here.
