Antilles Parmotremopsis

Parmelia antillensis

Parmelia antillensis Nylander, 1869, p. 264.

P. blastica Vainio, 1896, p. 32. [Type collection: Shawford Estate, Dominica, Elliott 899 (BM, lectotype; TUR, isotype).]

TYPE COLLECTION.—Matouba, Guadeloupe, Husnot 445 (H, Nylander Herbarium 35200, lectotype; G, P, isotypes).

DESCRIPTION.—Thallus adnate to loosely attached, whitish mineral gray, membranous, 6–10 cm in diameter; lobes subirregular, rotund, imbricate to crowded and convoluted, 4–5 mm wide; marginal cilia sparse; upper surface plane, continuous, becoming white-pruinose at the lobe tips, moderately isidiate, the isidia mostly simple, less than 0.5 mm high; lower surface densely rhizinate except for a narrow naked zone along the margins, black at the center and brown at the margin, the rhizines simple. Apothecia rare, adnate, 3–5 mm in diameter; spores 5–6×7–8μ.

CHEMISTRY.—Cortex K+ yellow (atranorin); medulla K+ yellow to red, C–, KC–, P+ pale orange (norstictic acid). A trace of salacinic acid is also probably present. The unknown spot accompanying norstictic acid in P. microblasta is lacking.

WORLD DISTRIBUTION AND HABITATS.—United States (Tennessee), Mexico, Honduras, West Indies; on hardwoods at mid-elevations (600–2,000 m).

This species is very common on citrus trees in the citrus belt along the west coast and is, in fact, the most commonly collected Parmelia on the island. It occurs only on canopy branches in undisturbed rain forest. The closely related nonisidate norstictic acid-containing P. phlyctina Hale was not found here. These two Caribbean endemics are the only species in section Imbricaria that produce norstictic acid.

SPECIMENS EXAMINED.—Shawford Estate, Elliott 1592 (TUR), 900 (BM, TUR, syntype of P. blastica Vainio); Laudat, Elliott s.n. (TUR), with 912 (TUR). Hale collections: 11 (35796), 14 (s.n., to be distributed in Vězda, Lichenes Selecti Exsiccati), 17 (35140), 18 (35592, 35596, 35598), 20 (35755, 35504), 21 (35333).