Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life habit: lichenized Thallus: crustose, superficial or immersed, often surrounded by a prothallus, often inconspicuous upper surface: various shades and combinations of white, gray, green, orange to pink, or brown; occasionally with isidia or schizidia photobiont: a trentepohlioid alga or Phycopeltis Ascomata: perithecial, often partly immersed in the thallus, occasionally with hairs or bristles involucrellum: always present but sometimes inconspicuous; true exciple: colored or not; yellowish to brownish, orange, reddish or black, often continuous below the hamathecium hamathecium: composed of unbranched or sparingly branched paraphyses; paraphyses: not anastomosing, non-amyloid; periphyses: present in a asci: cylindrical or sometimes elongate-ellipsoid or narrowly obclavate, functionally unitunicate, without conspicuous tholus, uniformly thin-walled, often with a tiny refractive apical ring, non-amyloid, 8-spored ascospores: 2-3 seriate, hyaline, fusiform to filiform, ellipsoid, bifusiform, or oblong, transversely 3-35 septate to muriform with eusepta, 13-120 x 2-20 µm; walls: not ornamented, with or without a gelatinous sheath Conidiomata: pycnidial, immersed to ± sessile conidia: bacilliform, rarely with macroconidia Secondary metabolites: absent or not characterized Geography: cosmopolitan, but most diverse in the tropics Substrate: mostly on bark, but also on living leaves, bryophytes, soil and on calcareous or siliceous rock. Notes: The new (different) systems of generic segregates within Porina as proposed by Harris (1995) and Hafellner and Kalb (1995) are not followed here, because several taxa are known that transcend the proposed borders (McCartney and Malcolm 1997). The genus is characterized by a combination of trentepohlioid photobiont (or Phycopeltis in many foliicolous species), perithecial ascomata with a hamathecium of usually simple paraphyses, uniformly thin-walled, functionally unitunicate asci, and colorless, euseptate and multiseptate to muriform ascospores.