Candelariella commutata
Candelariella commutata is a species of arctic–alpine, ground-dwelling, yellow crustose lichen in the family Candelariaceae. Formally described as new in 2013, the lichen forms bright egg-yolk-yellow crusts on calcareous soil and rock debris, typically growing above the tree line in arctic and alpine environments. It is known from the Caucasus, the Alps, high-elevation sites in Scandinavia, and the Russian Arctic, where it inhabits lime-rich ground in mountain fissures and detritus.
Taxonomy
Candelariella commutata was described in 2013 from Caucasian and European material that had long been filed under the name Candelariella unilocularis by some authors. The latter name, however, traces back to Alexander Elenkin's var. unilocularis, which was shown to belong within C. aurella; subsequent Scandinavian and Alpine usages of "unilocularis" conflated different entities, prompting Volker Otte and Martin Westberg to formally describe C. commutata as a distinct species. The holotype is from the Western Caucasus, on calcareous rock around 1,950 m elevation, collected on 6 September 1998.Description
The thallus forms a thin crust scattered as bright egg-yolk-yellow or tiny scales that sit flat on the substrate; in older material it may persist mainly as a yellow rim around the fruiting bodies. Apothecia begin immersed, then become exposed, usually flat and round but often developing lobed outlines, reaching about 2 mm across or a little more. The are yellow to ochre-yellow, often with a persistent, thick . A compact of elongated, thick-walled cells underlies the hymenium. The apothecial surface carries a fine dusting of minute brownish-yellow crystals.The hymenium is about 80 micrometres high; asci are of the Candelaria-type and contain eight spores. Ascospores are characteristically long sausage-shaped, typically 20–28 × 5–7.5 μm, with simple to sparsely branched paraphyses about 2 μm wide. Secondary metabolites detected by high-performance thin-layer chromatography analysis include calycin, pulvinic acid, and pulvic acid lactone. spot tests results on thallus material are K+, KC−, and C−. Some geographic variation has been noted: alpine and Scandinavian specimens tend to have somewhat shorter spores, and paraphysis tips can differ subtly between Caucasian and northern material.