Hypotrachyna isidiocera (Nyl.) Hale

Hypotrachyna isidiocera

Parmelia isidiocera Nylander, 1860:382. [Type collection: Cape Krusenstern, American Arctic, Beechey (BM, lectotype; H, isolectotype).]

Thallus loosely adnate, fragile, greenish mineral gray, 5–15 cm broad; lobes sublinear, short, often crowded; upper surface shiny, strongly white-maculate, becoming densely isidiate toward the margins, the isidia tall, erect, easily breaking off at the tips to reveal the yellow medulla; medulla sulphur yellow; lower surface densely rhizinate, the rhizines densely dichotomously branched. Apothecia rare, substipitate, 2–8 mm in diameter, the rim isidiate, rugose; spores 7μ–8μ × 12μ–16μ.

CHEMISTRY.—Cortex K+ yellow, medulla K+, C+ yellowish, P− (atranorin, barbatic acid, obtusatic acid, entothein, undetermined pigments, and other substances, rarely echinocarpic acid and a trace of norobtusatic acid).

DISTRIBUTION.—Mexico, Central America, West Indies, Colombia, Venezuela, Brazil, Hawaii.

HABITAT.—On trees (oak, pine) in virgin pine forests, cloud forests, and on rocks in open woods at 1000–3000 m elevation.