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Aspicilia plicigera (Zahlbr.) Rasanen
Family: Megasporaceae
[Lecanora plicigera Zahlbr.]
Aspicilia plicigera image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus with dark gray to yellowish ocher shades, closely crustose, very thin and continuous at the periphery, but not radiate there; to the inside of this outer band are radiate and occasionally branching higher lobes of convex verruciform areolae; cortex of vertically appearing cells in sections. Apothecia single per areolae; margin thick, entire, darkened next to the disk, I—; disk to 0.4 mm broad, black, bare, concave; hypothecium I—; epihymenium greenish brown; hymenium 70-100 ¡xm, 1+ bluish or greenish; paraphyses moniliform; spores 8, broadly ellipsoid, 10-15 x 5-8 µm. Conidia 25-30 x 0.6 µm (one observation by Magnusson (1939)).

Reactions: K—, C —, P—, I — .

This species grows on acid rocks. It is known from Novaya Zemlya and North America, where it occurs in Alaska and the Northwest Territories.

The status of this species is in some doubt, as the specimen photographed by Zahlbruckner (1928) is not this, but A. cingulata, according to Magnusson (1939), who also wrote that other specimens cited by Zahlbruckner included A. cingulata and A. rosulata. From the original material, Magnusson selected a lectotype, but his measurements of hymenium and spore sizes did not correspond with those of Zahlbruckner. A. plicigera closely resembles A. cingulata and may be a variant of that with longer conidia, 25-30 µm instead of 13-17 µm, and slightly more radiate-appearing thallus. But the latter character is very plastic in the arctic environment, and there is a strong possibility that these are synonymous. Other related species are Aspicilia sublapponica (Zahlbr.) Oxner, which according to Magnusson (1939) has only weak differences, and A. dendroplaca Magnusson, which has conidia 17-20 µm long, and more dendroid areolae.