Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Life habit: lichenicolous, gall-inducing Mycelium: immersed, invisible Ascomata: perithecioid (pseudothecia), about 10-20 per gall, entirely immersed in the host thallus and protruding only at the ostiole wall: hyaline throughout, only slightly brown in the ostiolar region, in section seen as small celled textura globosa intermingled with elongate elements hamathecium: present as interthecial filaments and short filaments in the ostiolar region; interthecial filaments: mostly simple, c. 2 µm thick; hymenial gel: I- asci: fissitunicate, cylindrical, 70-85(-90) x 11-15 µm, wall I-, 8-spored ascospores: hyaline, 3-septate, narrowly ellipsoid, (22-)24-28(-31) x 4-6(-7) µm, with a thin perispore; mature to overmature ascospores: with an external wall layer provided with tiny hyaline warts, this layer originating from the perispore, finally giving the spores a slightly yellowish appearance Conidiomata: pycnidial, also immersed in the galls, flask-shaped, with conidiogenous cells lining the cavity; microconidiomata: common, ovoid in section; wall: in section seen as small celled textura globosa conidia: bacilliform, c. 4 x 1 µm. Hosts: the thalli of Xanthoparmelia conspersa, X. cf. moctezumensis, X. sp.; further hosts known outside the Sonoran region: X. kamtschadalis (host of the type sub X. vagans), X. wildae; gall inducing, host thallus not discolored by the infection but galls concolorous with the healthy portions of the host thallus World distribution: known from a number of widely scattered localities in Europe (Austria, Germany, Italy), Asia (Mongolia), Africa (Canary Islands), North America (U.S.A. and Mexico), and South America (Venezuela) Sonoran distribution: so far known only from three localities in Arizona, Chihuahua, and Sonora with an altitudinal range from 680 to 2240 m. Notes: Ascospore size is somewhat variable in Trematosphaeriopsis parmeliana, which is not astonishing, as the fungus has a very wide distribution and can infest Xanthoparmelia species in a range of habitats. The spore size given by Elenkin (1901: 146) is close to the upper limit. Considerably smaller ascospores have been found in collections from other regions of the world, but the spore shape, the septation, and the presence of a perispore condensing into small warts are constant features.