Acarospora cervina (All Fungi)
Thallus variable in form, the areoles numerous, scattered, rounded, 0.5-3(-4) mm diam., sometimes combined into a crust, flat or convex, becoming lobulate, rather thick, pale green-grey to dark brown, the surface smooth or slightly roughened, matt, partly to entirely blue-grey pruinose, the pruina extending from the areole margin which is often eroded and white, the underside white. Photobiont layer irregularly uneven, discontinuous, penetrating the medulla below like teeth.
Anamorph: not known.
Teleomorph: ascomata apothecial, large, 2-3(-4) mm diam., sometimes absent, at times almost entirely occupying individual squamules. Thalline margin raised, swollen, disc flat or concave, concolorous or slightly darker than the thallus, reddish when wet, not pruinose. Hymenium 60–80(–100) μm tall. Interascal tissue of paraphyses 3 μm diam. at base. Asci more than 100-spored, clavate, apical dome K/I–. Ascospores 4-8 × 1.5-3 μm in size, hyaline, aseptate.
Chemistry: lichen products not detected by t.l.c.
In GB&I, assessed as of Least Concern but Nationally Scarce. Recorded from 33 vice-counties, including 30 since the year 2000.
The variably developed blue-pruina which is often restricted to the margins of the areoles is distinctive. The pruina may not extend over the ascoma surface.
Acarospora glaucocarpa has pruina confined to apothecia and the squamules are often sparse or absent, irregular to sub-lobulate, and often imbricate. It occurs in similar habitats.
Scattered and local, but present in many areas where suitable rocks occur. Most records are from the Midlands and East Anglia, the Pennines and Grampian mountains.
On hard limestones, epidiorite and other calcareous rocks, particularly in upland sites.