Synonyms: Callopisma albolutescens (Nyl.) Walt. Watson; Caloplaca albolutescens (Nyl.) H. Olivier; Placodium albolutescens (Nyl.) A.L. Sm.; Pyrenodesmia albolutescens (Nyl.) S. Y. Kondr.
Distribution: N - Frl. C - Tosc (Frolov & al. 2020). S - Si (Herb. Vondrák 10862).
Description: Thallus crustose to subleprose, episubstratic, granular and powdery, up to 200 μm thick, not lobed at margins, completely ecorticate, whitish to grey, forming orbicular, up to a few cm wide patches, several thalli often merging to cover larger surfaces. Center of thallus covered in abundant, grey, diffuse, granular soredia. Thallus surface and medulla with numerous colourless crystals insoluble in K, visible under polarized light. Apothecia zeorine, often numerous, circular to often irregular in outline, sessile, 0.5-1 mm across, with a flat, rust-red disc, a prominent, orange (paler than disc) proper margin, and sometimes a thin, soon disappearing thalline margin. Thalline exciple thin, rich in algae; proper exciple up to 85 µm thick, prosoplectenchymatous; epithecium brown-orange, K+ red; hymenium colourless 70-95 µm high; paraphyses richly branched in upper part, c. 1.5 μm thick at base, the apical cells up to 3.5 μm wide; hypothecium colourless, prosoplectenchymatous. Asci 8-spored, clavate, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, ellipsoid, (13-)15-18(-20) x 7-10(-12) μm, the equatorial thickening (“septum”) usually <4 μm thick (up to 1/4-1/5 of spore lenght). Photobiont chlorococcoid. Spot tests: thallus K- or K+ violet in sorediate parts, C-, KC-, P-; apothecia K+ red. Chemistry: soredia with the sedifolia-grey pigment: apothecia with chlorinated anthraquinones in both margin and disc: 7-chloroemodin (major), fragilin and emodin (minor), sometimes traces of parietin.
Note: this species is ecologically and morphologically very similar to K. teicholyta. K. albolutescens has a thin leprose thallus, the cortex is absent or poorly differentiated at margins, and marginal lobes are missing, whereas K. teicholyta has a rather thick thallus ehich is sorediate in the centre, while marginal lobes are more or less present and the cortex is well-developed, at least marginally.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)