Amundsenia approximata (Lynge) Søchting, Arup & Frödén

in Søchting, Garrido-Benavent, Seppelt, Castello, Pérez-Ortega, Asunción de los Ríos, Sancho, Frödén & Arup, Lichenologist 46: 774 (2014).

Basionym: Caloplaca vitellinula f. approximata Lynge, Lich. Nov. Zemlya: 222 (1928).


Thallus: episubstratic, irregular in outline, indistinct or composed of scattered or occasionally very aggregated areoles, up to 0.8 mm in diam; margin or the areoles simple or occasionally weakly effigurate; surface yellow or yellowish orange, smooth to uneven, matt, epruinose; hypothallus often present, poorly developed, visible between areoles, greyish black to black. Cortex 10-20 µm high, paraplectenchymatous; algal layer continuous; medulla hyaline and compact. Apothecia abundant, scattered or in loose groups, 0.5-1(-1.5) mm in diam., small to large, immersed when young, sessile when mature, initially not constricted, when mature slightly to strongly constricted, lecanorine; disc plane to convex, yellowish orange to orange, surface structure smooth to finely granulose, epruinose; thalline margin distinct to indistinct or occasionally prominent when on strongly eutrophicated substrates, thin to thick (10-15 µm), persistent or becoming excluded, not flexuose to occasionally flexuose, concolorous with or darker than remaining thallus surface, yellowish orange to orange, concolorous with disc or occasionally slightly brighter, smooth to crenulate. Excipulum to 80 µm wide, with many algal cells; cortex distinctly delimited (10-15 µm); inner part prosoplectenchymatous, strongly glutinized, not easily discerned, strongly swollen, hyaline; hypothecium of unoriented hyphae with narrow lumina, hyaline, oil droplets absent; subhymenium hyaline; hymenium 50 µm high, hyaline; paraphyses not gelatinized, ramifications scarce, terminal cells are swollen, to 4-6 µm wide, hyaline, subterminal cells to 2 µm wide; epihymenium distinct, yellow to yellowish orange. Asci 45 x 12 µm. Ascospores c. 8 per ascus, ellipsoid, (7-)8-10-11(-13) x (3-)3.5-4-4.5(-6) µm; septum 1-1.5 µm. (Søchting 2008: 76). Pycnidia unkown.

Photobiont: Data lacking.

Chemistry: Emodin, fallacinal, parietin, parietinic acid. Chemosyndrome A. All yellow parts K+ red, C-. (Søchting 2008: 76).

Ecology: On eutrophicated calciferous or unspecific rock, occasionally initially parasitic on other lichens.