Lecidea perlatolica

Lecidea perlatolica forms a crust-like thallus that breaks into small, tile-like patches (areoles). A dark border of fungal tissue (the prothallus) may be absent or show as a thin black to black-green line between patches. The areoles can touch or sit a little apart; those at the edge often develop narrow, lobed outlines. Individual areoles are flat to strongly domed, and in well-developed specimens can look like tiny scales or even short stalked bumps; they measure about 0.9–1.5 (rarely up to 3) mm across and 0.4–0.8 mm tall. The upper surface is pale to medium brown (occasionally darker toward the center), smooth and shiny to faintly roughened, and sometimes edged by a narrow pale or dark rim that may curl slightly downward. The outer skin (cortex) is stratified into three thin layers, the uppermost being a translucent sheet of dead, compacted cells. Beneath this lies a green algal layer and a white inner layer (the medulla), which turns a vivid violet when stained with iodine. In some specimens with scale-like areoles, a dark lower surface can be seen. The fruiting bodies (apothecia) are black, round to slightly irregular discs with a subtly narrowed base, usually 0.7–1.4(–2.3) mm in diameter. Their tops are flat to gently convex and may be matte or carry a faint dusting (pruina); a black rim typically remains visible. …

Lecidea perlatolica grows on acidic rock in open, well-lit sites within the montane to subalpine zones, at elevations between about 1,830 and 3,350 m (6,000 and 10,990 ft). It has been recorded from the western United States: California (Butte, El Dorado, Inyo, Los Angeles, Mono, San Bernardino, Tulare, and Tuolumne counties), Utah, and Nevada.