TYPE. GREAT BRITAIN. Cambria, Anglesey, Holy Island, Holyhead, 6.IV.1973, on maritime siliceous rocks, P.W. James s.n. (BM, holotype; US, isotype).
Description. Life form: lichenized fungus.
Thallus foliose, adnate to appressed, orbicular (1-)4-10 cm diam. (European) or 3-5.5 cm diam. (North American). Lobes becoming crowded and imbricate with age, irregular, subdichotomously to irregularly branched, 1-4 mm wide (European) or 0.4-1.5 mm wide (North American); margins entire or crenate, sometimes irregularly incised; tips truncate to roundish, often revolute. Upper surface light gray, becoming brownish at tips, shiny to matt, maculate, particularly at the lobe tips, developing cracks with age, pustulate; pustules submarginal and laminal, becoming coarsely sorediate; soredia typically blue-black, ultimately eroding away and revealing blackened lower cortex; medulla white; lower surface dark brown to black, with a pale brown margin, rugulose, moderately rhizinate; rhizines simple or sparsely to occasionally moderately dichotomously branched, continuing up to lobe apices or not, rarely projecting beyond lobe margins and appearing cilia-like. Ascomata not known; pycnidia rare; conidia not reported.
Substrate and Habitat. Saxicolous on noncalcareous rocks in sheltered or shaded microhabitats of outcrops or scree slopes.
Distribution. Europe and North America; in North Carolina found in the Blue Ridge ecoregion.
Literature
Lendemer, J.C. & J.L. Allen (2020) A revision of Hypotrachyna subgenus Parmelinopsis (Parmeliaceae) in eastern North America. The Bryologist123(2): 265-332.
Louwhoff, S.H.J.J. (2009) Hypotrachyna (Vain.) Hale 1974. Pp. 439-442 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.