Phaeophyscia leana is an endangered foliose lichen, described over a century ago, that was thought to be extinct until a small number of extant populations were found in recent decades. It is narrowly endemic to a small area in eastern North America where remaining populations area threatened by multiple forces.
Phaeophyscia leana is narrowly endemic to several small geographic areas in the U.S. states of Ohio (1 population), Illinois, Indiana, Kentucky, and Tennessee (1 population).
A summary of populations and population statuses was provided in 2002 (http://www.eiu.edu/biology/posters/2002-03.pdf). The species has been shown to be extirpated from a number of sites, including the type locality. Although >50 extant populations are known, the majority of these are small populations in geographically clustered locations. We consider the status of the species to be deteriorating throughout its range based on the continuing extirpation of known populations.
Population Trend: Deteriorating
The species occurs below the high water mark on the bark of hardwoods and conifers (Taxodium) in bottomland forests along rivers, oxbows, and sloughs inundated regularly by flooding.
The most significant threats to this species are the widespread alterations to water flow from dams and other regulation structures that have changed the unique habitats where the species occurs. Additional threats are pressure from development and other forces (industry, urbanization), pollution, road expansion and maintenance, logging and other threats that would further degrade remaining high quality natural habitats.
There are many conservation actions that can be taken including increasing protected areas in size and preventing further habitat degradation, educating and training land managers and local botanists to identify the species so we can monitor its health, federally listing the species as endangered in the United States, and improving air quality regulation, monitoring changes associated with sea-level rise. Policy and legislation considering biodiversity threatened by sea-level rise is also needed.
Further research that will aid in the conservation of this species includes population assessments and monitoring, population genetics studies, and ecological studies that incorporate threats to the species. Additionally, a species recovery plan needs to be written.
Gillespie, R.N., Methven, A.S. 2002. Phaeophyscia leana — a lichen species at the edge. Transactions of the Illinois State Academy of Science, Supplement 95: 77.
J. C. Lendemer 2009: Another record of the rare and endangered species Phaeophyscia leana. - Evansia 26(3): 142-143.
Skorepa, A.C. 1984. The rediscovery of Phaeophyscia leana. The Bryologist, 87: 257.
Thomson, J.W. 1963. The Lichen Genus Physcia in North America. Beihefte zur Nova Hedwigia, Heft 7. J. Cramer., viii + 172 pp.
Wilhelm, G. and Masters, L. 1994. The Current Status of Phaeophyscia leana (Tuckerman) Esslinger in Illinois. Report to the Illinois Department of Conservation.
Wilhelm, G., Masters, L., and Shimp, J. 2000. The Illinois Populations of Phaeophyscia leana, One of the World’s Rarest Lichens. Erigenia, 18:66–74.