Melanohalea subolivacea (Nyl.) Essl.
Brown-eyed Camouflage Lichen
Basis for Listing
Melanohalea subolivacea (brown-eyed camouflage lichen) is a species more typical of western North America, where it is fairly common on the bark of various tree species. In the Great Lakes region, M. subolivacea is apparently rare, having only been collected from a handful of sites in Wisconsin, Michigan, Ontario, and Minnesota (CNALH, 2017).
Melanohalea subolivacea was unknown in Minnesota until a population was discovered in Itasca State Park in 1975. Since this initial discovery, M. subolivacea has only been observed a handful of times (Voyageurs National Park; Wetmore 1981, and Grand Portage National Monument). Due to its rarity, Melanohalea subolivacea was listed as a species of special concern in 2013.
Melanohalea subolivacea is a foliose (leaf-like) lichen, with a greenish-brown thallus that has neither soredia nor isidia. The species is typically fertile and produces brown apothecia. All chemical spot-tests are negative.
In Minnesota, there are quite a few brown foliose lichens that may be confused with M. subolivacea. The species can be identified by the following combination of characteristics: M. subolivacea never has isidia or soredia, has abundant rhizines on the lower surface, almost always grows on bark or wood, does not react to any chemical spot-tests, and does not have (or rarely has) pseudocyphellae (Brodo et al. 2016).
In Minnesota, M. subolivacea has been collected too rarely to draw firm conclusions on habitat preference. All of the known populations were observed growing on bark or tree branches in fire-dependent forest and mesic hardwood forest communities in the Laurentian Mixed Forest Province.
Biology / Life History
Melanohalea subolivacea reproduces sexually. Spores are spread by wind, water, or potentially various animals and must land in suitable habitats. Once a spore has landed in a suitable area, it must find a specific algal partner in order for a thallus to form.
Best Time to Search
Searches for M. subolivacea can be conducted year-round, whenever they are not covered by snow or ice.
Conservation Efforts in Minnesota
As of 2017, all the known populations of M. subolivacea in Minnesota occurred in state parks or on federally protected lands. Should additional populations be discovered outside of these areas, loss of habitat is the primary threat to its survival. In Minnesota, M. subolivacea has been observed growing exclusively on tree bark; anything that removes this substrate would negatively impact this species. Lichens require specific microclimates. Anything that changes the microclimate, such as raising the humidity and light levels by opening up the canopy, must be avoided.
References and Additional Information
Blanco, O., A. Crespo, P. K. Divakar, T. L. Esslinger, D. L. Hawksworth and H. T. Lumbsch. 2004. Melanelixia and Melanohalea, two new genera segregated from Melanelia (Parmeliaceae) based on molecular and morphological data. Mycological Research 108(8): 873-884.
Brodo, I. M., S. D. Sharnoff, S. Sharnoff, and S. Laurie-Bourque. 2016. Keys to lichens of North America: revised and expanded. Yale University Press, New Haven, Connecticut. 424 pp.
Consortium of North American Lichen Herbaria (CNALH). 2017. <http://lichenportal.org/portal/collections/index.php>. Accessed 02 February 2017.
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.
Wetmore, C. M. 1981. Lichens of Voyageurs National Park, Minnesota. The Bryologist 84(4):482-491.