TYPE. UNITED STATES. “Trunks, North and South Carolina (Mr. Ravenel).” (Tuckerman 1872); Massachusetts, Bristol County, New Bedford, H. Willey s.n., s.d. (M, syntype; NY, isosyntype).
Life form. Lichenized fungus.
Description.Thallus crustose, ecorticate, grayish or brownish, thin, endophloedal; prothallus indistinct. Vegetative diaspores absent. PhotobiontTrentepohlia alga. Ascomata immersed to emergent, round to irregular, 0.75-1.25 mm diam.; disk flat, brownish to black, covered by coarsely white pruina; margin slightly raised above, whitish. Exciple hyaline, to brownish in outer portion; epihymenium brown, K-; hymenium hyaline to yellowish, clear. Asci 8-spored; ascospores hyaline, narrowly fusiform and somewhat curved, 3-septate, 18-30 x 5.5-8.5 μm. Conidiomata not reported.
Chemistry. Spot tests negative; no substances detected by TLC.
Substrate and habitat. Corticolous on deep, dry grooves between bark plates on oak trunks in shaded forests.
Distribution. Eastern North America; in North Carolina found throughout.
Note. Tuckerman (1872) notes two forms; one northern (Massachusetts, New Jersey) and one southern (North & South Carolina), which differ in spore size with the southern form larger. Harris (1990), who placed the species Arthonia glaucescens into Schismatomma based on the northern material alone, notes that the two forms may be different species and need further study.
Literature
Harris, R.C. (1990) Some Florida Lichens. Published by the Author, Bronx, N.Y. 109 pp.
Lendemer, J.C. & N. Noell. (2018) Delmarva Lichens: An illustrated manual. Memoirs of the Torrey Botanical Society28: 1-386.
Tuckerman, E. (1872) Genera Lichenum: An arrangement of the North America lichens. 281 pp (original description as Arthonia glaucescens Nyl. in litt.).
Willey, H. (1890) A synopsis of the genus Arthonia. New Bedford, USA. 62 pp.