Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Life habit: lichenized Thallus: crustose surface: yellowish ochre to olive-green, rarely white or cream-colored, often smooth and ±shiny, without soralia or isidia cortex: mostly well developed and consisting of periclinal hyphae medulla: often with large Ca-oxalate crystals photobiont: primary one a Trentepohlia green alga; secondary one absent Ascomata: apothecial, mostly lirellate, resembling thalline fissures with the thalline margins sometimes ±thickened, not carbonized, in some species inner apices of the margins brownish black exciple: not carbonized (few exceptions with labial tips/excipular lips slightly brown to carbonized) often rudimentary, rarely with thickened yellowish inner margins, in a few species with whitish excipular bases (increasing in width with age) hymenium: hyaline, not inspersed, 60-150 µm tall, I-, in cross section (particularly young parts) trapezoid-like or triangular [the "corners"/edges of the exciple often seem to be the growth zone of the hymenium and react I+ light blue] paraphyses: parallel, with hyaline tips, in few species tips warty and jutting out of the hymenium periphysoids: often present, hyaline, in some species with warty tips asci: clavate, I-, apex thickened with ±distinct ocular chamber ("Graphis-type"), 4-8-spored ascospores: hyaline, oval, rarely globose, 4-locular, submuriform or muriform, I-, I+ weak blue-violet, or I+ blue-violet (only few species), often halonate or with thick, jelly-like outer layer of the spore wall Conidiomata: pycnidial, rarely present (so far only reported for Fissurina globulifica), immersed in small brownish thallus areas (c. 0.1 mm in diam.), with narrow, crossed slits conidia: bacilliform to slightly bifusiform, formed acrogenously, conidiophore-type II (Vobis 1980), 4-6 x 1-1.5 µm Notes: Fissurina species are characterized by ascocarps that resemble thalline fissures ("fissurine" lirellae) with rudimentary, usually not carbonized exciples (a few species with carbonized excipular lips or well developed, thickened excipular bases). Ascospores are hyaline, usually oval/ovoid with ±thick, often jelly-like outer spore wall. Synonyms for Fissurina include Graphina Müll. Arg. p.p., and Graphis Adans. p.p. F. columbina: 1.Exciple laterally (at least apically) pale brown to carbonized; ascospores 4-locular, 16-20 x 7-9 µm; lacking psoromic acid ...............................