TYPE. UNITED STATES. Louisiana, St. Martin Parish, near St. Martinville, on trunk of Crataegus, 13.I.1894, A.B. Langlois 809 (MICH, holotype).
Description.Life form: lichenized fungus.
[modified from Dibben 1980] Thallus gray, greenish or yellowish gray, epiphloedal, thin or moderately thick; margin +/- entire and unzoned. Surface smooth or verrucuse, shiny, predominantly continuous to sometimes finely rimose, rarely areolate; areoles (0.2-)0.5(-1.0) mm diam. Vegetative diaspores absent. Fertile warts concolorous with the thallus, pertusariate or erect (ampliariate only where crowded), generally flat-topped with prominent radially-arranged marginal fissures, numerous to locally crowded, sometimes 2-3-(5) fused, (0.6-)1.0(-2.4) mm diam. Ostioles 1 or 3-5(-8) per wart, hyaline to more often black beneath, level or sunken, (0.05-)0.2(-0.3) mm wide, often grouped, rarely fused, in a central depression, (0.4-)0.6(-0.9) mm diam. Ascomata pertusarioid apothecia (1-)2-3(-4) per fertile wart, (0.32-)0.48(-0.74) mm diam. Hymenium colorless to white; hypothecium predominantly pale, rarely colorless; epithecium colorless or more often dark, K+ strongly violet. Asci cylindrical, (28-)44(-60) x (182-)283(-426) μm. Ascospores (2-3-)4 per ascus, uniseriate, longitudinal or oblique in ascus, ellipsoid or fusiform (20-)37(-53) x (50-)81(-123) μm, wall and lumen K-; outer spore wall (1-)3(-6) μm thick, sometimes thickest in midplane; inner spore wall (2-)5(-12) μm thick, smooth, rarely rough externally, unzoned and trimmed; end wall (6-)15(-26) μm thick. Pycnidia not known.
Chemistry. Spot tests negative; no identified substances detected by TLC.
Substrate and habitat. Corticolous hardwood trees.
Distribution. Southeastern North America; in North Carolina found in throughout.
Dibben, M.J. (1980) The Chemosystematics of the Lichen Genus Pertusaria in North America North of Mexico. Publications in Biology and Geology No. 5, Milwaukee Public Museum Press, Milwaukee. 162 pp (original description).