Micarea coppinsii

Thallus forming small rounded patches to 2 cm diam., sometimes wide-spreading, of discrete rounded grey-green to grey areoles 40–220 (–300) µm diam., many bursting apically to produce soralia; soralia green to blue-grey, 0.1–0.2 mm diam., with farinose soredia 12–25 (–30) µm diam., some with blue-green (K–, N+ red) pigmented hyphae; prothallus not evident; photobiont cells 4–7 µm diam. Apothecia very rare, similar to those of M. peliocarpa, to 0.2 mm diam., pallid to blue-grey, at first adnate and weakly marginate but becoming convex and constricted below and sometimes shortly stalked; hymenium 45–70 µm tall, colourless or partly greenish, K–, N+ red; asci 30–44 × 12–20 µm; ascospores 20–28 (–31) × 4 (–5) µm, fusiform to clavate-fusiform, ± curved, 3-septate. Pycnidia occasional, 60–70 µm diam., emergent, pallid, with microconidia 4.5–6 × 0.6–0.8 µm, narrowly fusiform-cylindrical. Thallus, soralia and apothecia C+ reddish (often faint), KC+ red, K–, Pd–, UV– (5-O-methylhiasic acid [major], gyrophoric acid [trace], ± lecanoric acid [trace]).

When soralia are blue-grey, the species is easily confused with diminutive forms of Trapeliopsis flexuosa or (when the soralia are pale) with Trapelia corticola; both these species have different, ± larger-celled photobiont cells and the major lichen product (TLC) is gyrophoric acid; also, the blue-green pigment in T. flexuosa is K+ brown, N–. On twigs, Halecania viridescens can look similar, but is C–, Pd+ red (argopsin). Sterile M. viridileprosa is distinguished by its light green ± leprose thallus without areoles.