Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: foliose, up to 2.5(-3) cm in diam., irregular to more often orbicular lobes: elongate and discrete or occasionally irregularly rounded and partly imbricate, 0.31(-1.5) mm broad, +flat, prostrate upper surface: gray to gray-brown, epruinose and without distinctive epinecral layer, sorediate soredia: powdery to granular, occasionally pseudocorticate and isidioid, in primarily terminal soralia that become reflexed and labriform or more often capitate/stipitate upper cortex: paraplectenchymatous medulla: white lower cortex: paraplectenchymatous lower surface: black, sometimes paler at the lobe ends, dull or rather shiny; rhizines: simple, black Apothecia: occasional, rarely up to 3 mm in diam., sessile; margin: entire, usually with a corona of rhizines ascospores: ellipsoid, 18-23(-25) x 7-11 µm, Physcia-type Spot tests: all negative in cortex and medulla Secondary metabolites: none detected (but rarely with a sparse K+ anthraquinone in the soralia). Substrate and ecology: on bark, rare on rocks World distribution: North America (primarily eastern), Europe Sonoran distribution: rare in the mountains of Arizona and Chihuahua. Notes: Phaeophyscia pusilloides is distinguished by the initially marginal (actually on the ends of short side lobes) or terminal soralia, which become clearly capitate (sometimes passing through a reflexed/labriform stage). At maturity the soralia often appear stipitate, due to their position on upright lobe ends. Phaeophyscia orbicularis sometimes has more or less reflexed marginal/submarginal soralia, occurring along with the predominantly laminal ones, but these never become distinctly labriform or capitate. Phaeophyscia insignis has rounded soralia that may appear nearly capitate, but they are mostlly laminal in origin. Also, this latter species has a pale tan to brown (not black) lower surface.