TYPE. UNITED STATES. New Hampshire, White Mts, on Acer saccharinum, s.d., E. Tuckerman s.n. (S, lectotype; BG, DUKE, FH, L, UPS, US, lectotypes designated in Sheard 2010).

Description. Life form: lichenized fungus              

[Modified from Sheard (2010)]

Morphology. Thallus crustose, very thin and partially within substrate or surficial, light gray to dark gray-green, continuous becoming rimose; surface plane to uneven, matt or often glossy; margin indeterminate; prothallus lacking or rarely determinate thin, black, entire. Vegetative diaspores absent. Photobiont chlorococcoid alga, likely Trebouxia. Ascomata lecanorine apothecia, erumpent, becoming broadly attached, frequent, scattered, sometimes becoming contiguous, up to 0.50 – 0.65 mm diam.; disk brown, often becoming black, plane or becoming convex, often eaten by invertebrates, sometimes becoming markedly convex upon regeneration; thalline margin concolorous with thallus or lighter with broken epinecral layer, entire, persistent or frequently eroded, 0.05 – 0.10 mm wide; proper margin absent or prominent if thalline margin eroded.

Ascomatal anatomy. Thalline exciple 45 – 70(-90) μm wide laterally and below; cortex 5-10 μm wide; epinecral layer often present; crystals absent from cortex and medulla; cortical cells (2.0-) 3.0 – 4.5 μm wide, rarely pigmented; algal cells 8.0 – 14.5 μm long. Proper exciple well-developed, (5-) 10 – 15 μm wide laterally, expanding to 15 – 35 μm above, sometimes pigmented light brown. Hypothecium hyaline, 30 – 65 μm deep; hymenium 75 – 115 μm high, not inspersed; paraphyses 2.5 – 3.5 μm wide, strongly conglutinate; tips expanded to 2.5 – 4.5 μm wide, pigmented light brown, immersed in a dispersed pigment, forming a light red-brown epihymenium. Asci 55 – 75 x 17 – 23 μm, 8-spored. Ascospores Type A development (i.e., apical wall thickening after septum formation), Physcia-type: (15.5-) 18.5 – 20.0 (-23.5) x (7.5-) 9.5 – 10.5 (-12.0) μm, mean l/w ratio 1.9 – 2.1, lumina remaining angular and canals persistent or becoming inflated, canals excluded, apical walls remaining thickened; torus usually present; walls smooth.

Conidiomata not seen.

Chemistry. Spot tests negative; zeorin plus unknown UV+ blue substance detected via TLC.

Substrate and habitat. Corticolous, mostly on hardwoods and most frequently on Acer saccharinum, in moist habitats. Sometimes collected with other Rinodina spp.

Distribution. North America (Great Lakes to northeastern and Appalachian mountains) and Siberia; 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.