Thallus immersed, appearing as a white stain; photobiont absent but clusters of chloroccoid algal cells surrounded by hyphae occasional. Ascomata biatorine apothecia, orange-brown, scattered, 0.2-1.0 mm diam, +/- gelatinous when wet. Exciple poorly developed; consisting of branched and anastomosing hyphae; epithecium reddish brown, not granular, pigment K+ dissolving; hymenium hyaline, 85-90 μm high, I+ pale blue; paraphyses much branched and anastomosing; hypothecium hyaline or pale straw-colored. Asci cylindrical-clavate, 70-80 x 10-12 μm, 8-spored and biseriate, apex rounded, thick-walled. Ascospores hyaline, simple, ellipsoid, 10-15 × 6-8 μm, often with a large, central oil drop.
Chemistry. No secondary compounds detected by TLC.
Substrate and Habitat. Lignicolous on conifer wood, rarely on bark.
Distribution. Australia, Eurasia, North and South America; in North Carolina reported from the Coastal Plain and Blue Ridge ecoregions, expected throughout.
Notes. The loose association of fungal hyphae with algal cells without the complex structure of a lichen thallus defines A. rufum as a borderline lichen.
Literature
Dobson, F.S., O.W. Purvis & P.W. James. (2009) Agyrium Fr. (1822). Page 121 in Smith, C.W., A. Aptroot, B.J. Coppins, A. Fletcher, O.L. Gilbert, P.W. James & P.A. Wolseley (eds.). 2009. The Lichens of Great Britain and Ireland. The British Lichen Society, London.
Fries, E. M. (1822) Systema Mycologicum.2(1): 1-274.