TYPE. “Habitat in Pinetis ad arbores prope terram inque ipsa terre e vegetabilibus putrefactis ortam Hercyniae Schrader, Lusatiae Mofig.” (Acharius 1810) E. Acharius 136 (BM 000500426, lectotype designated by P.M. Jørgensen 2009).
Description. Lichenized fungus.
Thallus crustose, evanescent to very thin, continuous, smooth, gray-green to oily greenish black. Photobiont Trentepohlia. Ascomata biatorine apothecia, 0.2-0.5 mm diam., sessile; disk concave to flat, yellow-orange; rim paler. Exciple hyaline; epithecium indistinct; hymenium 50-90 µm high, hyaline, I+ blue; paraphyses occasionally branched, distinctly septate, usually branched near apex with a pair of ±swollen apical cells. Asci narrowly cylindrical, 8-spored, wall thin, K/I+ blue, apex slightly thickened to give an amyloid ring around the pore. Ascospores hyaline, ellipsoid, 2-celled, 10-15 x 2-4.5 µm. Pycnidia frequent, whitish, 0.10−0.22 mm in diameter; conidia oblong, constricted at the middle, 6-8 x 2-2.5 µm.
Chemistry. None detected by TLC.
Substrate and Habitat. Corticolous on shaded acid bark of conifers and hardwoods, on tree bases or in crevices, rarely on other substrates.
Distribution. Pantemperate; in North Carolina found throughout.
Acharius, E. 1810. Lichenographia Universalis. 696 pp (original description as Lecidea pineti).
Benfield, B., O.W. Purvis & B.J. Coppins. (2009) Dimerella Trevis. (1880). Pp. 376-377 in Smith, C.W., A. Aptroot, B.J. Coppins, A. Fletcher, O.L. Gilbert, P.W. James & P.A. Wolseley (eds.). The Lichens of Great Britain and Ireland. The British Lichen Society, London (description as Dimerella pineti).