Rare Species Guide

  Basis for Listing

Pseudocyphellaria holarctica is a northern species that occurs in the United States in the Appalachians at high elevations, in the Lake Superior region, in New England, and in the Pacific Northwest. In our region it has always been rare. This species was collected by Fink between 1897 and 1902 in St. Louis, Koochiching, Lake, and Cook counties (Fink 1910). In the last 30 years, it has been found only once in St. Louis County. The extensive removal of mature, moist forests across Minnesota's forested landscape has seriously reduced the occurrence of this lichen in the state. For this reason, P. holarctica was listed as an endangered species in Minnesota in 1984.

  Description

A foliose lichen, P. holarctica has a tan or brownish thallus (lichen body) with small reticulate ridges on the upper surface. On the ends of the lobes of mature specimens, round patches of bright yellow soredia (powdery granules of algae and fungus) can be found. The middle layer of the thallus is mostly white, with some shades of yellow in spots. The lower surface has a somewhat furry appearance, with occasional small, yellow pores scattered about. Apothecia (fruiting bodies) are rarely seen. The algae associated with this species is blue-green (Wetmore 1981; Brodo et al. 2001).

  Habitat

Pseudocyphellaria holarctica is found in habitats that are moist, shady, and often foggy. Substrates for this lichen are varied, including mossy rocks and a variety of trees, especially Thuja occidentalis (northern white cedar) in mature hardwood and conifer forests. When found on trees, this lichen usually occurs 9-12 dm (3-4 ft.) above the ground and is at least partially shaded by the tree on which it is growing. All known Minnesota populations of this lichen are near water, and many are on offshore islands (U.S Forest Service 1999).

  Biology / Life History

This species reproduces asexually through the dispersal of soredia, which contain both fungal and algal components of the lichen. Dispersal methods are unknown, but soredia are most likely dispersed by wind. Transfer by other dispersal agents such as insects or other animals, is possible as well. In some parts of Europe, the yellow pigment in P. holarctica is a source of yellow dyes, but the lichen is not abundant enough in North America to serve as a dyestuff and it should not be collected for that purpose (Brodo et al. 2001).

  Conservation / Management

Pseudocyphellaria holarctica appears to be most affiliated with old-growth forests, and extensive historical logging destroyed much of its optimal habitat in Minnesota. Based on the number of sites where this lichen was historically collected, it presumably was more common 100 years ago than it is today. However, even then, Fink (1910) noted on his collections that this species was rare in several of the sites where he collected it. The rarity of this lichen today makes it difficult to accurately assess threats or offer conservation considerations. Any changes in the humidity of its forest habitat could hurt populations of P. holarctica, as could exposure to air pollution. Even considering information on this lichen from around the world, it is difficult to tell whether this species is moving north or simply dying out (U.S. Forest Service 1999).

Pseudocyphellaria holarctica may be observed year-round, whenever lichens are not covered by snow or ice.

  Conservation Efforts in Minnesota

This species and other rare lichens are being targeted for botanical searches by scientists in an attempt to locate additional occurrences and conserve remaining populations.

  References and Additional Information

Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. Lichens of North America. Yale University Press, New Haven, Connecticut. 795 pp.

Fink, B. 1910. The lichens of Minnesota. Contributions from the United States National Herbarium 14(1):1-250.

Lucking, R., B. Moncada, B. McCune, E. Farkas, B. Goffinet, D. Parker, J. L. Chaves, L. Lokos, P. R. Nelson, T. Spribille, S. Stenroos, T. Wheeler, A. Yanez-Ayabaca, K. Dillman, O. T. Gockman, T. Goward, J. Hollinger, E. A. Tripp, J. Villella, W. R. Alvaro-Alba, C. J. Arango, M. E. S. Caceres, L. F. Coca, C. Printzen, C. Rodriguez, K. Scharnagl, R. Rozzi, E. Soto-Medina and L. S. Yakovchenko. 2017. Pseudocyphellaria crocata (Ascomycota: Lobariaceae) in the Americas is revealed to be thirteen species, and none of them is P. crocata. The Bryologist 120(4):441-501.

U.S. Forest Service. 1999. Population viability assessment in forest plan revision. Statement of purpose and reason. Draft species data records: Pseudocyphellaria crocata. United States Forest Service, Region 9.

Wetmore, C. M. 1981 (revised 2005). Keys to the Lichens of Minnesota. Department of Plant Biology, University of Minnesota, St. Paul, Minnesota. 92 pp.

Wetmore, C. M. 2002. Conservation assessment for Pseudocyphellaria crocata (L.) Vain. United States Forest Service, Eastern Region, Milwaukee, Wisconsin. 12 pp.