Pyxine sorediata

Pyxine sorediata has a foliose thallus that ranges in colour from dull bluish-grey to green-gray. The lobes comprising the thallus measure 1–2.5 mm wide, and are pruinose at the tips;^[7] they are in close contact, often overlapping.^[10] The lobe margins also have white pseudocyphellae, that contrast with the lobe;^[11] they are concentrated on the lobe margins and are rarely on the lamina.^[10] The medulla is light yellow to yellow, and this colour is sometimes present in the soralia.^[10] The underside of the thallus is black to greyish black; it has small rhizines that help attach it to its substrate. Structures called soralia are on the margins of the lobes, but sometimes form round patches on the lamina. The soredia (reproductive structures) are coarse and grainy with a dark grey colour; they tend to impart a grey colour to the central part of the thallus.^[11] Apothecia are quite rare in this species. The ascospores measure 12–17 by 6–8 μm.^[10]

Pyxine sorediata is the largest species of Pyxine.^[7] It does not have any reaction to the standard lichen spot tests.^[11] Secondary chemicals reported from the species include atranorin and unidentified triterpenes.^[10]

Phylogenetic studies have shown that the corticolous Chinese species Pyxine hengduanensis is closely related to P. sorediata. Unlike P. sorediata, which has a yellow medulla and soralia that develop marginally from fissures and then become laminal and disc-shaped, P. hengduanensis has marginal labriform soralia that develop from the centre of the pseudocyphellae, with grey to bluish-grey soredia and a pale yellow medulla.^[12] Another lookalike is Pyxine endochrysina, but that species has isidia that range in form from granular to finger-like.^[13]

The lichen is widely distributed in northeastern North America.^[7] It grows on bark, on acidic rocks, and on moss. In Europe, where it is generally rare,^[14] Pyxine sorediata is typically collected from mossy rocks.^[11] It has been recorded in the Pyrenees, the Caucasus, in the Uholka-Shyrokyi Luh primeval beech forest in the Ukrainian Carpathians,^[14] and from the eastern coast of Lake Baikal in Siberia.^[15] Its northernmost European record is from the Bavarian-Bohemian Forest.^[14] In Australia, it occurs in areas with uniform tropical environments, subtropics, and warm temperate areas. Specimens from Queensland have been collected from elevations up to 1,000 metres (3,300 ft). Pyxine sorediata is also known from East Africa, Japan,^[10] South Korea,^[13] and China.^[12]