Type. NE GREENLAND. Kapp Humboldt, in rupe calcarea, s.d. B.A. Lynge s.n. (fragment of holotype - MSC!, holotype - O not available).
Rinodina parvula H. Mayrhofer & Poelt, Biblioth. Lichenol. 12: 1979: 138. Type. JUGOSLAVIA. MACEDONIA. Šar planina, Rudoka, Popova šapka W Tetovo, Hänga W der Bergstation, 2000 m, 8.7.1977, J. Poelt s.n. (GZU - holotype!). Buellia parvula (H. Mayrhofer & Poelt) H. Mayrhofer & Scheidegger, Lichenologist25: 354.
Description.Thallus thick to very thick, dark grey, areolate, areoles irregular to 1.20-1.30 mm wide; surface rugose, shining; margin indeterminate; prothallus lacking; vegetative propagules lacking. Apothecia innate to broadly attached, frequent, often contiguous becoming angular by compression, to 0.60‑0.90 mm in diam.; disc black, plane, sometimes becoming slightly convex and fissured; thalline margin concolourous with thallus or darker if epinecral layer absent, 0.05-0.10 mm wide, entire, persistent; excipular ring absent. Apothecial Anatomy. Thalline exciple (55-)70-90 µm wide laterally when present; cortex 10-15 µm wide; epinecral layer usually present, 5‑20 µm deep; crystals absent in cortex and medulla; cortical cells pigmented, to 5.0‑7.5 µm wide; algal cells to 12.0‑17.5 µm long; thalline exciple sometimes ca. 55 µm wide below; proper exciple hyaline or light brown, or dark brown if thalline exciple absent, (5-)10‑20 µm wide laterally, to (20-)30‑50 µm above; hypothecium hyaline, (40-)60-70 µm deep; hymenium 80‑110 µm high, not inspersed; paraphyses 2.0‑3.0 µm wide, not conglutinate, with apices and penultimate septa darkly pigmented, to 4.5-6.0(‑7.0) µm wide, forming a dark brown or red-brown epihymenium; asci 50-75 x 15-31 µm. Ascospores 8/ascus, development type A, Milvina-type, (13.5-)15.5‑16.5(-18.5) x (7.5-) 9.5‑10.5(-13.0) µm, average l/b ratio 1.5-1.7, septal wall thickening in some spores and very rarely apical wall thickening when immature, uniformly thin walled and constricted when mature; torus well developed in immature spores, becoming hidden by wall pigmentation; walls becoming strongly ornamented. Pycnidia immersed in thallus; conidiophores type VI but not branched; conidia bacilliform, 5.0-6.0 x ca. 1.5 µm.
Chemistry. Spot tests all negative; secondary metabolites not detected (Scheidegger 1993).
Substrate and Ecology. Lynge (1940) and Mayrhofer and Poelt (1979) state that the species occurs on slightly calcareous rocks but the North American specimen is on HCl- rock.
Distribution. Recorded from North America for the first time, Summit Co., Colorado, from the alpine zone. Previously known from Greenland and the alpine zone of southern Europe (Mayrhofer 1984a as R. parvula).
Notes. This species is characterized by its thick thallus and broadly ellipsoid, Milvina-type spores with heavily ornamented walls. Scheidegger (1993) included R. parvula in Buellia on the basis of its Beltraminia-type spores and an exciple belonging to the aethalea-type. However, the asci belong to the Lecanora-type (Rambold et al. 1994) and young spores have obvious septal wall thickening, occasional apical wall thickening and become constricted at maturity, all characteristics of the Milvina-type. Apothecia in the North American and other specimens typically have thalline margins early in development and an hyaline hypothecium. The dark grey rather than brown colour of the thallus is due an epinecral layer masking the cortical pigmentation. The species is best placed in the genus Rinodina where its thick thallus and spore type make it a good fit with the Milvina-group of species.
The single North American record was identified previously as R. parasitica (Mayrhofer 1984a) but that species is characterized by Physcia-type spores which are of similar length although they are less broadly ellipsoid (l/b ratio 1.7-1.9).
Specimen examined. U.S.A. COLORADO. Summit Co., North facing slope of North Star Mountains, south of Quandary Peak, near Blue Lake reservoir, 3580-3750 m, 106.07W 39.22N, 6th September 1977, J. Poelt s.n. (GZU).
Selected References. Mayrhofer & Poelt (1979 Abb. 6 as R. parvula), Mayrhofer (1984a as R. parvula), Scheidegger (1993 as Buellia parvula), Giralt (2001 Plate XII: D as “Buellia” parvula).
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus white or ashy-white, crustose, irregular, not well limited, to 1 mm thick, vemicose-areolate with deep chinks, the areolae to 1 mm broad, angular, bull ate, with secondary chinks and then somewhat roughened; with narrow, black hypothallus. Apothecia commonly contiguous and becoming angular, to 1 mm broad, deep in thallus like Lecidea tesselata but not aspicilioid; margin black, thin, becoming crenulate to disappearing; exciple exterior brownish to brownish violet, interior hyaline; disk flat or depressed, black, scabrid; hypothecium hyaline; epihymenium dark; hymenium 90 μm, upper part dark, lower hyaline; asci clavate; paraphyses slightly thickened above to 3 μm, tips dark; spores 8, 1-septate, center slightly constricted, walls thickened and lumina subangular, brown, 14-18 x 7-8 μm.
Reactions: K-, C-, P-, I-.
This species grows on calcareous rocks. It is known from Cape Humboldt, northeastern Greenland, the Okpilak River, northern Alaska, and the Melville Hills, Northwest Territories.