Common Name: Nested beard lichen
Scientific Name: Usnea nidulans Motyka sens. lat.
Species in the genus Usnea are tufted or pendulous fruticose lichens with a pale greenish or yellowish tinge. Branching patterns are various but often many short perpendicular side branches called fibrils are present. The main branches are often covered with small bumps called papillae. They are round in cross section with a dense central cord (axis) surrounded by a cottony medulla and a dense cortex (Brodo and others 2001, McCune 2005). Important characters for species identification are the relative thickness of the cortex, medulla, and central cord, as well as the type of soralia present.
Usnea nidulans is shrubby or slightly pendant and usually less than 12 cm in length (Goward 1999). It is distinguished from other Usnea species by the presence of clustered fibrils that occur in bundles of 2 to 4, in combination with the following suite of characters (Halonen et al. 1998). The cortex is green to yellowish-green, translucent, distinctly glossy and relatively thin, making up 6-12% of the radius. Coloration at the base is pale to strongly blackened. The medulla is cottony. The central cord is white and makes up more than one third of the branch diameter. The sparse branches are mainly unequal in length, and form approximately 90º angles at the axil. The branches are segmented by ringed cracks which often have thin, white medullary rings. Secondary branches are not at all constricted at the point of attachment. Papillae are low and indistinct. Soralia are tuberculate when present, and bear isidia or fibrils when young. There are occasionally depressions and foveoles present (Halonen et al. 1998, Goward 1999, McCune 2005).
Diagnostic characters include the presence of clustered fibrils, the non-inflated branches, and the hypermaritime distribution (Goward 1999).
The taxonomic status of this species is uncertain in the Pacific Northwest. Material from the Pacific Northwest is close to the type material from South America but may represent a new taxon (Goward 1999, Halonen et al. 1998). The North American populations are being called Usnea nidulans sensu lato until further taxonomic work is completed (Halonen et al. 1998).
Soralia and isidia are often present. Apothecia are rare within the genus so reproduction is through asexual propagules. Soralia are helpful for identification but not essential. The species can be identified year-round.
Range, Distribution, and Abundance:
The type specimen of Usnea nidulans is from Argentina, and the species was only known from South America until it was first documented (as U. nidulans sensu lato) in western North America in 1998 (Halonen et al. 1998). It has been found in the Coast Range ecoregion of British Columbia, Washington and Oregon (Halonen et al. 1998, ORNHIC 2004). This species is rare to scattered in humid, hypermaritime forests at lower elevations (Halonen et al. 1998). Collections that are published in the literature come from the Carl G. Washburne Memorial State Park in Oregon and from the Queen Charlotte and Vancouver Islands in British Columbia (Halonen et al. 1998). There is also a site from an air quality plot on the Hebo Ranger District of the Siuslaw National Forest about 2 miles north of Euchre Mountain above Cedar Creek (http://www.fs.fed.us/r6/aq/ ).
This species occurs exclusively in hypermaritime forests on the immediate coast and in the Coast Ranges (Halonen et al. 1998, Goward 1999, Halonen 2000, McCune 2005). It grows on conifers and deciduous trees. Documented substrates include Picea sitchensis on the Queen Charlotte Islands and Tsuga heterophylla and a dead deciduous tree on Vancouver Island (Halonen et al. 1998).
No specific information concerning threats to this species was found but timber harvest would be the obvious threat given its substrate and habitat.
Although no considerations specific to this species were found in the literature, given the rarity of this species, surveys in suitable habitat, and management of known sites would help provide protection for this species. Where found, consider maintaining the substrate and microclimate by limiting timber harvest and activities that could reduce the canopy within the immediate vicinity of the site.
Other pertinent information (includes references to Survey Protocols, etc):
Keys are available in Halonen et al. (1998), Goward (1999) and McCune (2005).
Detailed site locations (Halonen and others 1998)
Preparer: Kimiora Ward
Date Completed: March 2006
Revised: Richard Helliwell, March 2007
Rob Huff, July 2007
Attachment 1 – References
Brodo, I.M., S.D. Sharnoff and S. Sharnoff. 2001. Lichens of North America. Yale University Press, New Haven, New Hampshire, USA. 795 p.
Goward, T. 1999. The lichens of British Columbia, illustrated keys. Part 2, Fruticose species. Victoria, BC, Canada: British Columbia Ministry of Forests Research Program. 319 p.
Halonen, P. 2000. Studies on the lichen genus Usnea in East Fennoscandia and Pacific North America. Acta Universitatis Ouluensis A Scientiae Rerum Naturalium 340:1-29.
Halonen, P., P. Clerc, T. Goward, I. M. Brodo and K. Wulff. 1998. Synopsis of the genus Usnea (Lichenized Ascomycetes) in British Columbia, Canada. The Bryologist 101:36-60.
McCune, B. 2005. Usnea in the Pacific Northwest. Unpublished report. Oregon State University, Corvallis, Oregon. 17 p. Available: http://oregonstate.edu/~mccuneb/getkeys.htm [Accessed March 6, 2006].
Oregon Natural Heritage Information Center. 2004. Rare, threatened and endangered species of Oregon. Oregon Natural Heritage Information Center, Oregon State University, Portland, Oregon. 105 p.
Attachment 2 – Detailed site locations (Halonen and others 1998).
1 – Queen Charlotte Islands, Kunghit Island, Howe Bay, on Picea sitchensis, ca sea level, 52º01’N, 131º03’W, 1971, Brodo 17654 & Wong (CANL).
2 – Vancouver Island, Ucluelet, on Tsuga heterophylla, ca sea level, ca 48º55’N, 125º32’W, 1982, Goward 82-1808 (UBC).
3 – Vancouver Island, Clayoquot Lake, W side, on dead deciduous tree, 15 m, 49º13’N, 125º30’W, 1993, Wulff 94-227 (UBC).
4 – Oregon, Carl G. Washburne Memorial State Park, 1990, Goward 90-306 (UBC).
5 – Oregon, About 2 miles north of Euchre Mtn. on crest above Cedar Cr., A. Mikulin, 8-11-1994, 44o 51’ 55” N, 123o 51’ 47” W.