Tetramelas Norman,
Type : Tetramelas geophila (Flörke ex Sommerf.) Norman [=Lecidea geophila Flörke ex Sommerf.]
Description : Thallus crustose, spreading on mosses, soil and decaying vegetation. Photobiont green, chlorococcoid. Ascomata apothecia, disc black, epruinose. Hypothecium mostly more than 150 μm thick, dark-brown to carbonaceous. Hymenium colourless, not inspersed with oil droplets. Hamathecium of paraphyses, strongly branched, apical cells swollen to 4–5 μm diam., with a brown, strongly pigmented cap. Asci Bacidia -type (Malcolm & Galloway 1997: 187). Ascospores brown, 1- or 3-septate, 25–35 × 8–10 μm.
Chemistry : Containing 6- O -methylarthothelin (C+ orange).
Tetramelas, included in the family Physciaceae nom. cons. (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), comprises 10 species characterised by large ascospores, the presence of 6- O -methylarthothelin, and a high-alpine, arctic or antarctic distribution (Marbach 2000; Nordin 2000 – as Buellia, 2004; Kalb 2004a; Nordin & Tibell 2005). Species colonise soil, lignum, or plant debris or bryophytes in exposed, alpine to high-alpine tundra habitats. One species is known from the mountains of southern New Zealand (Galloway et al. 1998; Nordin 2004).
