Parmotrema Lichen

Parmelia subcrinita

Parmelia subcrinita Nylander, 1890, p. 26.

TYPE COLLECTION.—Japan: Hirosaki, Almquist (H, Nylander Herbarium 35479, neotype).

DESCRIPTION.—Thallus loosely adnate, 10–20 cm in diameter, whitish mineral gray; upper surface plane, dull, reticulately cracked in older parts, becoming white-pruinose at the tips, isidiate, isidia cylindrical, up to 0.3 mm high, simple or branched; margins of lobes ciliate, cilia short, 1–2 mm long; lower surface black and sparsely rhizinate at the center, brown and naked in a broad zone at the margins. Apothecia rare, 3–6 mm in diameter; disc imperforate; spores 8–10×12–14μ.

CHEMISTRY.—Cortex K+ yellow (atranorin); medulla K+ yellow turning red, C–, KC–, P+ orange (salacinic acid). There may be unknown substances accompanying these acids but their identity is not clear.

WORLD DISTRIBUTION AND HABITATS.—United States, Mexico, Central and South America, West Indies, Azores, Japan, Indonesia, Sabah; on rocks but also on trees at lower to midelevations (sea level to 2,000 m).

This species was collected in Dominica only on rocks at Rodneys Rock. It has previously been confused with P. crinita Acharius, which contains stictic acid and is smaller and more fragile. There is intergradation with P. subisidiosa (Müller-Argau) Dodge, which has rhizines more or less to the margin below, a strongly reticulately cracked cortex to the edge of the lobes, and more marginal or localized isidia. In some parts of its range P. subcrinita could be confused with P. subtinctoria Zahlbruckner, an isidiate species with shiny maculate cortex and a mostly brown lower surface with fine rhizines to the margin.

SPECIMEN EXAMINED.—Hale collection: 35729 (to appear in Weber, Lichenes Exsiccati).