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Arthopyrenia punctiformis (Pers.) A. Massal. (redirected from: Arthopyrenia atomaria)
Family: Arthopyreniaceae
[Arthonia cembrina Anzi,  more]
Arthopyrenia punctiformis image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus not lichenized, bark discolored around the ascocarps.

Ascocarps dark brown or black, 0.1-0.25 mm broad, at first within bark, soon uncovered; excipular wall lacking below, dark above; hyphae between the asci branched and nearly parenchymatous, sometimes appearing moniliform in KOH; spores 8, irregularly arranged, hyaline, 1-septate, elongate-ellipsoid with thin, gelatinous sheath, 15-20 x 4.5-6/xm.

This species is found on a variety of barks, including Acer, Alnus, Betula, and Quercus. It is listed in Zahlbruckner’s Catalogus as cosmopolitan.