TYPE. UNITED STATES. South Dakota. Minnehaha County, outcropping of Sioux quartzite, E of Sioux River, 2 miles S of Hwy 38, between Rowena and East Sioux Falls, ~1300 ft, 31.XII.1956, W.A. Weber S8490 (COLO, holotype; CANL, DUKE, FH, MIN, MSC, US, WIS, isotypes).
Description.Life form: lichenized fungus.
[Modified from Sheard (2010)]
Morphology. Thallus crustose, thin, dark gray to greenish-brown, rimose-areolate; areoles up to ~0.50 mm wide, margins sometimes raised; surface plane to minutely verrucuose, matt; margin determinate; prothallus absent to thin, entire or sometimes fimbriate, brownish. Vegetative diaspores absent. Photobiont chlorococcoid alga, likely Trebouxia. Ascomata lecanorine apothecia, sometimes immersed, usually broadly to narrowly attached, frequent, sometimes contiguous, up to 0.45 – 0.60 mm diam.; disk black, plane, sometimes becoming convex; thalline margin concolorous with disk or thallus, ~ 0.05 mm thick, entire or becoming excluded; proper margin present to absent.
Ascomatal anatomy.Thalline exciple 45-75 μm wide; cortex 5-10 μm wide laterally; epinecral layer absent; crystals absent from cortex and medulla; cortical cells darkly pigmented, 5.0 – 8.5 μm wide; algal cells 11.5 – 16.0 μm long. Proper exciple 10 – 15 μm wide laterally, hyaline, expanding to 20 – 40 μm above; hypothecium hyaline, 40 – 80 μm thick; hymenium 70 – 100 (-150) μm high, not inspersed; paraphyses 2.5 – 3.5 μm wide, not conglutinate, tips expanded to 4.5 – 5.5 μm wide, heavily pigmented, usually forming a dark brown epihymenium. Asci 50 – 65 x 16 – 19 μm, 8-spored. Ascospores Type B development (i.e., apical wall thickening before septum formation), Pachysporaria-type II: (12.5-) 15.5 – 16.5 (-19.5) x (7.0-) 8.5 – 9.5 (-11.5) μm, mean l/w ratio 1.7 – 1.9, lumina irregularly angular at first, becoming lacrimiform then rounded; torus developing late, narrow; walls smooth.
Conidiomata. Pycnidia semi-immersed; conidiophores Type I (Vobis 1980, Vobis & Hawksworth 1981); conidia bacilliform, 3.5 – 4.0 μm.
Chemistry. Spot tests negative; secondary metabolites not detected via TLC.
Substrate and habitat. Saxicolous on siliceous rocks, in moist habitats, such as boulders in stream banks and lakeshores. When growing in frequently inundated habitats the apothecia an immersed and the thalli may be more continuous. The species may also be lichenicolous on other crustose lichens (Aspicilia spp.) in amphibious habitats.
Distribution. Scattered throughout eastern North America, as far west as Colorado; in North Carolina found in the Blue Ridge ecoregion.
Literature
Sheard, J.W. 2010. The Lichen Genus Rinodina (Lecanoromycetidae, Physciaceae) in North America, North of Mexico. NRC Research Press, Ottowa.
Vobis, G. (1980) Bau und Entwicklung der Flechten-Pycnidien und ihrer Conidien. Bibliotheca Lichenologica14: 1-141.
Vobis, G. & D.L. Hawksworth (1981) Conidial lichen-forming fungi. Pp. 245-273 in G.T. Cole & B. Kendrick (eds.): Biology of Conidial Fungi. Volume 1. Academic Press, New York,
Sheard, J.W. 2010. The lichen genus Rinodina (Ach.) Gray (Lecanoromycetidae, Physciaceae) in North America, north of Mexico. NRC Press, Ottowa, Ontario, Canada. 246 pp.