TYPE. [AUSTRIA. Klagenfurt, vicinity of Zigguln Castle] “frequens tamen in faxis lapidibusque sylvarum Zigulnensium, praeprimis in lapideo aggere sylvam circumdantem, retro Castellum, vulgo Ziguln.” (Jacquin 1791: 184; Tab. 15: Fig. 1.); figure typified in Index Fungorum. Neotype (Hertel 1977): AUSTRIA. Kirnten: Klagenfurt, 1881, Arnold s.n., Am. Lich. Exs. 894 (M; isoneotypes, DUKE, UPS).

Description. Lichenized fungus.

Thallus crustose, continuous, finely rimose when dry, light brownish to greenish; vegetative diaspores soredia in soralia, rare (in exposed habitats); prothallus often weak or absent, black. Photobiont Trebouxia alga. Ascomata lecideine apothecia, immersed to sessile, 0.5-1.5 mm diam, frequent, especially near thallus center. Disk flat to slightly convex, black, covered in white pruina; exciple dark brown to blackish, paler inward; epithecium brown to dark brown; hymenium hyaline, 70-110 um high; subhymenium 20-40 μm high; paraphyses conglutinate and often indistinct, weakly to moderately anastomosed. Asci 8-spored. Ascospores colorless, ellipsoid, simple, 17-25 x 6-10 μm.

Chemistry. Secondary metabolites include stictic acid (main), cryptostictic acid, constictic acid, and norstictic acid.

Substrate and Habitat. On siliceous rocks in shaded, humid areas, often along waterbodies.

Distribution. Australia and New Zealand, eastern to southeastern Asia, Europe, and eastern North America; in North Carolina recorded from west of the Fall Line (i.e., in the Piedmont and Blue Ridge ecoregions).

Literature

Gowan, S. P. (1989) The Lichen Genus Porpidia (Porpidiaceae) in North America. The Bryologist 92(1): 25-59.

Hertel, H. (1977) Gesteinsbewohnende Arten der Sammelgattung Lecidea (Lichenes) aus Zentral-, Ost- und Sudasien. Khumbu Himal, Ergebnisse des Forschungsunternehmens Nepal Himalaya 6: 145-378.

Jacquin, N.J. (1791) Collectanea ad botanicam, chemiam, et historiam naturalem spectantia 2: 1-374 (original description as Lichen albo-caerulescens)

Wang XY, Joshi Y, Hur JS. (2011) A lichen genus Porpidia (Porpidiaceae) from South Korea. Mycobiology 39(1): 61-63.