Bulbothrix Lichen

Parmelia laevigatula

Parmelia laevigatula Nylander,1885, p. 614.

P. hookeri Taylor, 1847, p. 169. [Type collection: St. Vincent, Guilding (FH-Tayl, lectotype; BM, isotype).]

TYPE COLLECTION.—Guiana, South America, Le Prieur (H, Nylander Herbarium 35653, lectotype).

DESCRIPTION.—Thallus closely adnate on bark, rather thick, 3–9 cm in diameter, whitish mineral gray; lobes linear, short, 0.5–2.0 mm wide; marginal bulbate cilia dense, conspicuously inflated, often apically ciliate; upper surface plane to convex, continuous, moderately isidiate, the isidia simple or branched, up to 0.3 mm high; lower surface black, densely rhizinate, the rhizines richly branched. Apothecia adnate, 1–5 mm in diameter, the exciple coronate; spores 3–4×5–7μ.

CHEMISTRY.—Cortex K+ yellow (atranorin); medulla K–, C+, KG+ red, P– (lecanoric acid).

WORLD DISTRIBUTION AND HABITATS.—Southeastern United States, West Indies, and northern South America; on palms and hardwoods at lower elevations (sea level to 1,200 m).

Parmelia laevigatula is a typical lichen of dry scrub woodlands in Dominica. The thallus is whitish and the marginal bulbate cilia unmistakable under a hand lens. Related species that do not occur on Dominica include P. confoederata Culberson, a much smaller lichen without isidia in southeastern United States, and P. scortella Nylander, similar externally but with an olive greenish cast and gyrophoric acid.

SPECIMENS EXAMINED.—Hale collections: 1 (35687) and 10 (35441).