TYPE. “Ad corticem arboris prope Krausses-Lagoon (542: C. Raunkiaer) Fair Plane (F. Boergesen) in insula S. Croix (Wainio 1915). UNITED STATES. U.S. Virgin Islands, Saint. Croix.

Description. Lichenized fungus.

Thallus foliose, white to grayish green, suborbicular, 1-8 cm broad, dull, often pruinose toward the margins; lobes confluent, appressed, often appearing crustose; vegetative diaspores absent; medulla white; lower cortex black; rhizines absent. Photobiont trebouxoid alga. Ascomata lecanorine apothecia, common to abundant, 0.5-1 mm diam., sessile; disk flat, dark purple-red, red-pruinose; thalline rim thin; excipular rim indistinct. Exciple thin, poorly developed; epithecium pale to dirty red, granular, K+ yellow and dissolving pigment; hymenium hyaline, ~80 μm high; paraphyses slightly branched at apices, not capitate; hypothecium brown-black, K-. Asci clavate, 8-spored, in 2 rows; ascospores brown, 2-celled, thick-walled, 15-18 x 6-7 μm.

Chemistry. Cortex K+ yellow, C-, PD-; medulla K-, KC-, C-, PD-; atronorin and divaricatic acid.

Substrate and Habitat. Corticolous and lignicolous, primarily on trees.

Distribution. Pantropical, north into eastern North America; in North Carolina found in the Coastal Plan ecoregion.

Literature

Awasthi, D.D. (1975) A Monograph of the Lichen Genus Dirinaria. Bibliotheca Lichenologica No. 2, J. Cramer, Lehre. 108 pp. 

Moore, B.J. (1968) The macrolichen flora of Florida. The Bryologist 71(3): 161-266

Wainio, E.A. (1915) Additamentum ad lichenographiam Antillarum illustrandam. Annales Academiae Scientiarum Fennicae A6(7): 1-226 (original description as Physcia purpurascens).