Summary: Features include a small reddish orange cup or disc, paler exterior dotted and barred with brown, absent stem, growth on burnt ground, and microscopic characters. Another species, listed for Washington and Alberta by Larsen, is Anthracobia nitida Boud., is probably a synonym of this species.
Microscopic: spores 16-18 x 7-8 microns, oblong-elliptic, smooth, with two oil drops; asci up to 200 x 15 microns; paraphyses slender, clavate, enlarged to 7 microns wide at tips; at the margin, "surface cells are subglobose with thin brown walls and bear short, broad, thin-walled, 1-2-celled hairs, a few up to 70 x 23 microns, the majority only 1-celled and about 25 x 15 microns", (Dennis), spores 16-18 x 8-9 microns, broadly elliptic, smooth, colorless, with 2 droplets; asci 8-spored, 160 x 15 microns; paraphyses cylindric, septate, tips thickened to 7 microns wide; hairs (clavate hyphal outgrowths) 25-60 x 10-15 microns, 1-celled or 2-celled, (Breitenbach)
Notes: A. macrocystis is found in BC, OR, ID, and CA, (Larsen).
Habitat and Range
SIMILAR SPECIES
Anthracobia melaloma is a more yellowish ochraceous shade of orange, paraphyses do not stain green in Melzer''s reagent, and hairs have several septa (in A. macrocystis they are more rudimentary short hairs with only one septum). Pyronema omphalodes does not have tufts of hair on exterior, is more or less confluent rather than just crowded, is more pink in color, and has a conspicuous white cobwebby subiculum.
Habitat
on burnt ground, July to October, (Dennis for UK), gregarious to crowded on burned ground (Breitenbach for Switzerland)