Myelochroa aurulenta

Appearance

Thallus: foliose, moderately to loosely adnate, ± circular, 4-10 cm broad, subdichotomously to irregularly lobate lobes: sublinear to subirregular, 2-4 mm wide, sinuous in the axils, contiguous to somewhat imbricate; apices: subrotund; margin: entire or crenulate, ciliate; cilia: short, up to 0.8 mm, mostly in lobe axils upper surface: pale green to bluish gray (whitish gray in herbarium), shiny, smooth to rugulose centrally, sorediate soredia: farinose to granular, arising from coarse pustules or soralia that become broad and diffuse; isidia: absent medulla: white to pale yellow, yellow-orange under the soralia; algal layer continuous lower surface: black with a brown zone (1-5 mm wide) peripherally, smooth to rugulose, densely rhizinate; rhizines: simple to furcate, or squarrosely branched Apothecia: rare, sessile to subpedicellate, 2-5 mm diam. ascospores: poorly developed, 10-12 x 5-7 µm Pycnidia: rare, immersed conidia: bifusiform, 5-6 x 1 µm Spot tests: cortex: K+ yellow, C-, KC-, P-; medulla: K-, C-, KC-, P- or pigmented area turning darker yellow in K Secondary metabolites: upper cortex with atranorin and chloroatranorin and secalonic acid A; medulla with zeorin, leucotylic acid, and, where pigmented, secalonic acid A.

Naming

Myelochroa aurulenta (Tuck.) Elix & Hale, 1987
Hypotrachyna aurulenta (Tuck.) Krog & Swinscow
Parmelia aurulenta Tuck.
Parmelia aurulenta var. aurulenta Tuck.
Parmelia aurulenta var. silvestris (Degel.) Degel.
Parmelia silvestris Degel.
Parmelina aurulenta (Tuck.) Hale

Distribution

Pantropical, eastern North America and Japan.

Habitat

On trees and rocks, in woodlots and along roads in open habitats but more shade tolerant than many species and can frequently be found in forests where few other species grow.