Coenogonium
Thallus crustose, thin and inconspicuous or well developed, smooth or granular, grey-green. Photobiont Trentepohlia.
Anamorph: conidiomata pycnidia, half to three-quarters immersed in the thallus, yellowish or whitish-pink, wall colourless. Conidiogenous cells 5-9 × 1.8-2.5 μm, arising singly or several together from branched supporting cells, cylindrical or bottle-shaped. Conidia ellipsoidal, aseptate, colourless, sometimes biguttulate.
Teleomorph: ascomata apothecia, sessile, marginate, concave-urceolate to flat, pinkish-white or pale yellow, at least when young, to yellow-orange. Thalline exciple absent. True exciple colourless, mostly pseudoparenchymatous. Hymenium 50-90 μm high, I+ blue. Interascal tissue of occasionally branched, distinctly septate paraphyses, usually branched near the apex with a pair of ± swollen apical cells. Asci 8-spored, narrowly cylindrical, wall thin, K/I+ blue, Catillaria-type. Ascospores ellipsoidal, 1-septate, colourless, smooth, without a perispore.
Chemistry: no lichen products detected by t.l.c.
The genus differs from the primarily tropical Coenogonium Link (1820) only in the algae, and as this is phylogenetically not significant, Dimerella is increasingly merged with that genus. Absconditella species lack Trentepohlia, have an I- (or reddish) hymenium, and indistinctly septate paraphyses.
In humid, shaded or sheltered habitats, on leaves, over mosses, or on mainly acidic bark.