Lecanora epanora (Ach.) Ach.
A Species of Rim-lichen
Basis for Listing
Lecanora epanora (a species of rim-lichen) was first documented in North America in 1980 from a site in British Columbia (Brodo et al. 1987). Since that time, only a handful of additional sites have been located in North America, including sites in Alaska, Pennsylvania, Colorado, Ontario, and Minnesota. In Minnesota, L. epanora is restricted to two cliff/talus communities in Cook County, and extensive surveys have not lead to the discovery of additional sites. Lecanora epanora was listed as a threatened species in Minnesota in 2013.
Lecanora epanora is a crustose (crust-like) lichen, with a bright yellow areolate thallus (lichen body). Areolae often have soredia (powdery vegetative reproductive structures) on the upper surface, giving this lichen a grainy appearance under magnification. Apothecia (small disk-like fruiting bodies) are flat to slightly convex, yellow-brown to brown in color, and are surrounded with a distinct rim that is the same color as the thallus, though apothecia appear to be rare in Minnesota specimens. All chemical spot tests (chemical tests used in lichenology) are negative; however, this species does fluoresce bright orange when exposed to UV light (Edwards et al. 2009).
In Minnesota, L. epanora can be separated from similar species based on the following combination of traits: Lecanora epanora only occurs on mineral-rich (typically iron-rich) rock, has an areolate thallus that is bright yellow, and does not react to any chemical spot tests (Lendemer 2010).
In Europe, L. epanora typically occurs in dry shaded overhangs on metal-rich (mainly iron-rich) rocks (Edwards et al. 2009). In Minnesota, L. epanora is restricted to a few northern open talus communities and their associated northern mesic cliffs. These communities are located in the Rove Formation of the eastern Border Lakes Subsection of the Laurentian Mixed Forest Province. This region is known to contain many other state rarities due to its unique geology and landscape.
Biology / Life History
Lecanora epanora reproduces asexually through the dispersal of soredia. Soredia are reproductive structures that contain both fungal and algal partners and can be dispersed over short distances. This species also reproduces sexually through the distribution of spores by wind, rain, and animals.
Conservation / Management
All known occurrences of L. epanora in Minnesota are located within the Boundary Waters Canoe Area Wilderness (BWCAW). The talus slopes on which L. epanora occurs are dynamic but fragile systems. Shifting rocks or rock slides could bury entire populations of this species. Anthropogenic disturbance to these talus slopes is likely the main threat to the perpetuation of this species in the state. Hikers and sightseers would likely be the primary causes of decline for this species in Minnesota. Efforts should be made to minimize impacts to the talus slopes on which L. epanora occurs.
Best Time to Search
Searches for L. epanora can be conducted year-round, whenever lichens are not covered by snow or ice.
References and Additional Information
Brodo, I. M., W. J. Noble, T. Ahti, and S. Clayden. 1987. Lichens new to North America from the flora of British Columbia, Canada. Mycotaxon 28(1):99-110.
Edwards, B., A. Aptroot, D. L. Hawksworth, and P. W. James. 2009. Lecanora. Pages 465-502 in C. W. Smith, A. Aptroot, B. J. Coppins, A. Fletcher, O. L. Gilbert, P. W. James, and P. A. Wolseley, editors. The lichens of Great Britain and Ireland. Second edition. British Lichen Society, London, England.
Lendemer, J. C. 2010. Preliminary keys to the typically sterile crustose lichens in North America. Published by author, Eagle Hill, Maine. 34 pp.+32 plates. [available at: http://sweetgum.nybg.org/southeastlichens/biblio_detail.php?irn=250001].
Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.