Hypotrachyna Lichen

Hypotrachyna imbricatula

Parmelia imbricatula Zahlbruckner, 1909:168. [Type collection: Itapecirica, São Paulo, Brazil, Schiffner (W, lectotype; MICH, isotype).]

Parmelia lobulifera var. luteoreagens Degelius, 1941:61. [Type collection: Myrtle Point, Mt. LeConte, Tennessee, U.S.A., Degelius (DEGEL, lectotype).] For additional synonymy see Hale, 1971a:16.

Thallus adnate, 5–10 cm in diameter, whitish mineral gray but often turning pale tannish in the herbarium; lobes sublinear, often crowded, 2–4 mm wide; upper surface plane, shiny, usually strongly white-maculate, moderately isidiate, the isidia thin, cylindrical, simple to branched, sometimes darkening at the tips; lower surface densely rhizinate, the rhizines densely dichotomously branched. Apothecia infrequently developed, 2–10 mm in diameter; spores 7μ–10μ × 11μ–16μ.

CHEMISTRY.—Cortex K+ yellow, medulla K−, C+ orange, P− (atranorin, barbatic acid, 4-O-demethylbarbatic acid, obtusatic acid, and norobtusatic acid).

DISTRIBUTION.—Southeastern United States southward to Chile.

HABITAT.—On trees (oaks, pine, juniper, Araucaria, Arbutus, coconut palm, citrus), stumps, rocks, and (rarely) soil, in primary and secondary forests at 200–2600 m elevation.

Parmelia imbricatula

Parmelia imbricatula Zahlbruckner, 1909, p. 168.

P. laevigata f. isidiosa Müller-Argau, 1891, p. 377. [Type collection: Ootacamum, Nilgherries, India, Foulkes (K, holotype; G, isotype).]

P. lobulifera var. luteoreagens Degelius, 1941, p. 61. [Type collection: Myrtle Point, Mt. LeConte, Tennessee, Degelius (DEGEL, lectotype).]

P. inconstans Zahlbruckner in Magnusson and Zahlbruckner, 1944, p. 94. [Type collection: Kahaluamano, Kauai, Hawaii, Rock 175 (W, holotype; US, isotype).]

TYPE COLLECTION.—Near Barra Mansa, Itapecirica, Sao Paulo, Brazil, Schiffner (W, holotype; MICH, isotype).

DESCRIPTION.—Thallus adnate, 5–10 cm in diameter, whitish mineral gray but turning pale tannish in the herbarium; lobes sublinear-elongate, 2–3 mm wide; upper surface plane, shiny, strongly maculate, moderately isidiate, the isidia thin, rarely branched, sometimes darkening at the tips; lower surface densely rhizinate, the rhizines dichotomously branched. Apothecia rare (not seen in Dominica), 2–10 mm in diameter; spores 7–10 × 11–16μ.

CHEMISTRY.—Cortex K+ yellow (atranorin); medulla K–, C+, KC+ yellowish orange, P– to faint (barbatic acid, 4-O-demethylbarbatic acid, obtusatic acid, “norobtusatic acid,” and other unknowns). The information on chemistry has been kindly supplied by Dr. C. F. Culberson, who is studying the complex chemistry of the barbatic acid-containing Parmeliae. The distinct KC+ orange reaction is a characteristic of these species.

WORLD DISTRIBUTION AND HABITATS.—Southeastern United States, West Indies, Mexico and Central America, Brazil, Hawaii, Taiwan, Philippines, Malaysia, and Thailand; on conifers and hardwoods at mid to high elevations (1,000–3,500 m).

This common pantropical montane lichen (although lacking in Africa) is characterized by isidia and presence of barbatic acid. Close relatives are the sorediate P. laevigata, also known from Dominica, and nonsorediate P. boliviana Nylander. A nearly morphologically identical isidiate species with evernic acid instead of barbatic is P. bogotensis Vainio, which does not occur in the Lesser Antilles.

Parmelia imbricatula is a rain forest lichen in Dominica, seemingly rather rare. It could be misidentified as P. costaricensis without a chemical test with KC.

SPECIMEN EXAMINED.—Hale collection: 21 (35345).