***PRELIMINARY ASSESSMENT POST-NEW YORK WORKSHOP
Proposed Authors: J.C. Lendemer and J.L. Allen
Common Name: Bull Neck Lips
Current Scientific Name: Acanthothecis leucoxanthoides Lendemer & R.C. Harris
Key Metrics: COLORED TEXT BOX
Proposed Status: Critically Endangered: B2a,b(ii,iii,iv); C2a(i); D.
EOO: 0.000 km2
AOO: 8.000 km2
# of Documented Locations: 2 (both presumed extant)
Assessment Synopsis. – Acanthothecis leucoxanthoides is a rare script lichen known from two locations in the Coastal Plain of southeastern North America. Though recently described, additional populations of the species have not been located despite extensive study of the small amount of suitable habitat that persists in a region severely fragmented and degraded by anthropogenic forces. The immediate threats to A. leucoxanthoides stem from lack of protections of existing populations, further degradation and fragmentation of suitable habitat, and declines in the already small population.
Distinguishing Traits. – This crustose lichen can be recognized by its occurrence on bark, pale, elongate lirellae that lack black carbonized areas, simple labia containing concentrations of stictic acid, ornamented paraphyse tips, non-inspersed hymenium, and small, hyaline 6–10 celled ascospores (15–18(–21) × 4–5 μm).
Distribution and Ecology. – The species is restricted to the bark of hardwood trees in humid, wet swamp forests of the Coastal Plain of southeastern North America where it is known from two locations (one each in Georgia and North Carolina). Despite extensive inventories by multiple specialists of suitable habitats throughout the region over a period spanning +20 years (e.g., Florida: W.R. Buck, R. Commons, R.C. Harris, F.&J. Seavey; Georgia: S.Q. Beeching, M.F. Hodges, J.C. Lendemer; North Carolina, South Carolina and Virginia: W.R. Buck, R.C. Harris, J.C. Lendemer), no additional locations have been located. While it is possible that additional populations will be located in the future, thus expanding the AOO and EOO, the available data clearly illustrates that the species is rare and the population is severely fragmented.
Status of Populations – Two populations have been documented and are presumed to be extant. Both populations are small in size comprise <25 individuals each (for a total of <50 individuals). The North Carolina population is located in a protected management unit, however the site is not specifically designated as a natural area that would improve protection of the species. The population in Georgia is not located in a protected area, and is within a small forest block within a fragmented natural landscape.
Protected Status. – None.
Threats. – Suitable forest habitats throughout the Coastal Plain of the southeastern United States have been substantially impacted and fragmented by centuries of habitat loss and degradation, particularly in the form of logging, ditching and draining, and clearing for sylviculture or agriculture. Remaining suitable habitats are for the most part highly fragmented and degraded, and the species has not been located in the small number of large protected areas that do exist. Trends of habitat loss and degradation are continuing at present and projected to increase in the future (Brown et al. 2005, Hall & Schafale 1999, Napton et al. 2010, Ricketts et al. 1999, Terando et al. 2014). These trends will be further exacerbated by climate change and sea-level rise, the latter of which is projected to inundate the North Carolina location by 2100 (Lendemer & Allen 2014, Sallenger et al. 2012).
Explanation of Proposed Rank. – This species merits ranking as Critically Endangered: B2a,b(ii,iii,iv) based on the small number of documented locations (2) both of which comprise a small number of individuals (<25 each), low AOO (8.000 km2), the 50% reduction in population size inferred from loss of the North Carolina population as a result of sea-level rise by 2100, and the documented declines in habitat quality historically, at present, and projected into the future. The species also ranks as Critically Endangered C2a(i) based on the small population (<50 mature individuals) the small number of individuals in each subpopulation (two subpopulations each with <25 individuals). Further the species also ranks as Critically Endangered D based on the overall small size of the population which is estimated to be <50 mature individuals.
Conservation Recommendations. – In addition to formal listing as an endangered species, conservation of the species would be effected by enhancing protected status of the existing location in a protected management unit (North Carolina) and by acquisition/conservation easement of the Georgia location for the purpose of habitat protection. Given the small number of populations, and the threats posed by adjacent road/utility right-of-ways and by sea-level rise, monitoring and potentially translocation are also warranted.
Brown D. G., K. M. Johnson, T. R. Loveland & D. M. Theobald. 2005. Rural Land-Use Trends in the Conterminous United States, 1950-2000. Ecological Applications 15:1851–1863.
Hall, S. P. & M. P. Schafale. 1999. Conservation Assessment of the southeast Coastal Plain of North Carolina, using site-oriented and landscape-oriented analyses. Raleigh.
Lendemer, J.C./ Allen, J.L. 2014: Lichen Biodiversity under threat from Sea-Level Rise in the Atlantic Coastal Plain. - BioScience 64: 923-931.
Loveland T. R. & W. Acevedo. 2000. Land Cover Change in the Eastern United States. United States Geological Survey, Land Cover Trends Project. Website: http://landcovertrends.usgs.gov/east/regionalSummary.html (accessed 10March2010).
Napton, D. E., R. F. Auch, R. Headley & J. L. Taylor. 2010. Land changes and their driving forces in the Southeastern United States. Regional Environmental Change 10: 37–53.
Ricketts, T.H., E. Dinerstein, D.M. Olson & C.J. Loucks. 1999. Terrestrial ecoregions of North America: a conservation assessment. Island Press, Washington, D.C.
Sallenger A.H. Jr., K.S. Doran & P.A. Howd. 2012. Hotspot of accelerated sea-level rise on the Atlantic Coast of North America. Nature Climate Change 2: 884–888.
Terando, A.J., J.K. Costanza, C. Belyea, R.R. Dunn, A.J. McKerrow & J. Collazo. 2014. The southern megalopolis: using the past to predict the future of urban sprawl in the Southeast U.S. PLOS ONE 9(7): e102261
Acanthothecis leucoxanthoides is endemic to the Mid-Atlantic Coastal Plain of eastern North America where it is known from a single low-lying swamp forest that is threatened by sea-level rise and other forces. The known range of the species lies within the Dare Regional Biodiversity Hotspot and is projected to be inundated by sea-level rise by 2100.
Acanthothecis leucoxanthoides is known from a single location in a swamp fores ton the south shore of Great Creek at the east end of Indian Island within the North River wetlands of northeastern North Carolina in the Mid-Atlantic Coastal Plain of eastern North America. Extensive fieldwork throughout the southeastern United States has failed to locate additional populations of this species.
Demographic studies are needed to assess and monitor the population size. Our current knowledge of the species suggests that its population is stable.
Population Trend: Stable
This species occurs on the bark of hardwoods in a remnant rich hardwood (Liriodendron, Acer, Magnolia, Nyssa) and cypress (Taxodium).
The only known population occurs within the Mid-Atlantic Coastal Plain, a region where only 12% of original “natural habitat” persists. In addition to intense pressure from development and other forces (industry, urbanization), much of the remaining habitat including the only known location of this species is imperiled by sea-level rise. Additional threats include pollution, road expansion and maintenance, and logging.
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.
Lendemer, J.C. and R.C. Harris. 2014. Seven new species of Graphidaceae (Lichenized Ascomycetes) from the Coastal Plain of southeastern North America. Phytotaxa.
Lendemer, J.C. and J. Allen. 2014. Lichen Biodiversity under threat from Sea-Level Rise in the Atlantic Coastal Plain. BioScience 64: 923-931.