Lecanora hafelliana

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Lecanora hafelliana is a bark-dwelling crust-like lichen in the Lecanoraceae family. It was described in 2011 from South Korea and typically grows on the bark of broadleaf trees such as maples, birches, dogwoods, and oaks in temperate mountains of northeast Asia, at elevations around 680–1,660 meters.

The lichen forms a grey crust tightly attached to bark, spreading as a continuous film that ranges from dull whitish to ash-grey. Its surface is uneven and wart-like, with a sharply defined edge and no dark border around the colony.

There are many apothecia (fruiting bodies) that are stalkless and 0.5–1.6 mm across. Each has a thick, pale rim that is usually lighter than the crust. The disc is yellowish-brown to dark reddish-brown and may carry a thin white coating in older material.

Chemical tests on the thallus give K+ (yellow), KC+ (yellow), and P+ (pale-yellow) reactions, indicating the presence of atranorin, usnic acid, zeorin, the stictic acid complex, and hafellic acid.

Under the microscope, the amphithecium is packed with tiny potassium hydroxide-soluble crystals and is capped by a clear outer cortex up to 100 μm thick. The epihymenium is dark brown with coarse K-soluble granules; the hymenium is colorless and about 45 μm tall. The subhymenium and hypothecium are also colorless. Each ascus contains eight colorless, single-celled ascospores that are ellipsoid to narrowly ellipsoid, about 10.5–15 by 6.2–7.8 μm. Paraphyses are simple and unpigmented, and no pycnidia (asexual-spore structures) have been observed.

Lecanora hafelliana is distinguished by its thick pale rim, the crystal-rich amphithecium, and its particular mix of secondary metabolites, which set it apart from other Lecanora species.

Distribution and habitat: In Korea, it is common on the bark of a wide range of broadleaf hosts across the lower montane to sub-alpine belt, roughly 730–1,660 m in elevation. Its range extends into northeastern China, where it has been found on Korean pine at about 680 m. In Korea, it occurs in crustose lichen communities with species such as Arthonia apatetica, Lecanora lojkahugoi, Lecidella mandshurica, and Rinodina xanthophaea.