“Tiny Button Lichen”: {A. punctuata}

Names: Amandinea punctata, Buellia punctata, Tiny Button Lichen

Identification Characteristics

Description: Thallus thin & barely perceptible to moderately thick, cracked or areolate.  Exciple uniformly pigmented dark brown.

Colour: Gray to brownish. Green when wet.

Apothecia: 0.2 – 0.5 mm in diameter, with a thin black margin that often disappears in maturity

Spores: (7-) 11 – 16 x (4-) 5 – 8 um, not constricted, 8 per ascus.

Substrate: On various types of bark & wood, & occasionally on siliceous rock.

Lookalikes: Amandinea polyspora, an East Temperate species, is very much like A. punctata but has 12 – 32 spores per ascus, somewhat smaller spores (7.5 – 11.5 x 3.5 – 5.5 um), & an exciple that is pale within.  It grows only on bark.  Two species of Amandinea with incipient to well-developed lecanorine margins are A. milliaria (aka R. milliaria).  The latter has apothecia that erupt from the pale gray thallus, sometimes leaving a very thin thalline border outside the lecideine margin.  It is almost entire coastal, from Main to Texas, with a few records from the shores of the Great Lakes.  Amandinea dakotensis has a dark gray-green thallus, & the apothecia, although also initially erupting, finally have well-developed lecanorine margins as in species of Rinodina.  It is found throughout the midwest, rarely occurring on the east coast.

Bibliography: Lichens of North America, by Brodo, Sharnoff, & Sharnoff

Database Entry:  Distance Everheart 12-26-13

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