TYPE. UNITED STATES. South Carolina, Santee Canal (Woodbine Spring, 1859), on Ulmus americana, H. Ravenel s.n. (BM, lectotype selected by Salisbury 1971; FH-Tuck, isolectotype).
Description.Life form: lichenized fungus.
Thallus crustose, endophloedal to epiphloedal to 300 μm thick; surface pale greenish-gray to pale gray, continuous to verruculose, smooth to rugulose; vegetative diaspores isidia, sparse to abundant, globular to elongate, unbranched. Cortex absent; photobiont trentepohlioid alga in a well-developed layer with crystal inclusions; calcium oxalate crystals abundant; medulla usually absent; lower cortical-like layer present. Ascomata choorodiscoid apothecia up to 2 mm diam., round to irregular, often fused, immersed to erumpent; disk black, white-pruinose; excipular rim indistinct; thalline rim margin often split and lobed, paler than thallus or whitish, becoming recurved. Exciple fused, apically carbonized, pale to yellowish brown below; epithecium distinct, hyaline to brownish, formed by densely interwoven, branched paraphysal tips; hymenium hyaline, not inspersed, strongly conglutinated, up to 120 μm high, I-. Asci 8-spored, tholus thin; ascospores brownish, ovoid to oblong-ellipsoid, 3-4-septate to submuriform; locules rounded to angular, 12–25 × 8–12 μm. Pycnidia cylindrical, immersed in the thallus, more often on isidia tips visible as blackish dots; conidia bacilliform to bifusiform, 4-8 x 1.5-2.0 μm.
Chemistry. Spot tests negative; no substances detected by TLC.
Substrate and Habitat. Corticolous hardwood trees.
Distribution. Pantropical, north into southeastern North America; in North Carolina found in the Coastal Plain and Piedmont ecoregions.
Notes.Reimnitzia santensis is in a monotypic genus characterized by the erumpent apothecia with ragged thalline walls, epihymenium composed of intertwining paraphysal tips and short spores.
Kalb, K. (2001) The lichen genus Topeliopsis in Australia and remarks on Australian Thelotremataceae. Mycotaxon79: 319-328.
Mangold, A., J.A. Elix & H.T. Lumbsch. (2009) Thelotremataceae. Flora Australia57: 195–420.
Tuckerman, E. (1862) Observations on North American and other lichens. 2. Proceedings of the American Academy of Arts and Sciences5: 383-422 (original description as Thelotrema santense).