***PRELIMINARY ASSESSMENT POST NEW YORK WORKSHOP
Proposed authors: J.C. Lendemer & J.L. Allen
Common Name: Stingy Spored Lip Lichen
Current Scientific Name: Acanthothecis paucispora Lendemer & R.C. Harris
Proposed Status: Critically Endangered A3c; B2a,b(i-v); C2a(i); D
EOO: 0.000 km2
AOO: 8.000 km2
# of Documented Locations: 2 (both presumed extant)
Assessment Synopsis. – Acanthothecis paucispora is a rare script lichen known from two locations in the Mid-Atlantic 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 threats to A. paucispora stem from degradation and fragmentation of suitable habitat, as well as projected impacts from sea-level rise.
Distinguishing Traits. – This crustose lichen can be recognized by its occurrence on bark, pale, elongate lirellae that lack black carbonized areas, simple labia, ornamented paraphyse tips, non-inspersed hymenium, short, hyaline 4-5 celled ascospores (16–20 × 6–8μm), and absence of secondary metabolites.
Distribution and Ecology. – This species is restricted to the bark of hardwood trees that occur in small pockets of mature upland hardwood forest habitat surrounded by large, wet, humid swamp forests in the Mid-Atlantic Coastal Plain of eastern North America (North Carolina). The Mid-Atlantic Coastal Plain has been subjected to intensive large scale lichen biodiversity inventory by multiple experts (J.L. Allen, W.R. Buck, R.C. Harris, J.C. Lendemer, and 30+ members of the Tuckerman Workshop in 2014), yet no additional subpopulations for the species have been found. Similarly despite extensive inventories by multiple specialists of suitable habitats elsewhere in the Coastal Plain 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), no additional subpopulations have been located. While it is possible that additional subpopulations will be located in the future, thus expanding the AOO and EOO, the available data clearly illustrates that the species is rare.
Status of Populations – Two subpopulations have been documented and are presumed to be extant. Both populations are small and composed of <25 mature individuals (i.e., total population is estimated at <50 mature individuals). One location is included within Croatan National Forest, although not within a wilderness area or other management subunit that would afford additional protections. The other subpopulation is located in a protected unit managed by North Carolina State University, however that subunit is not currently part of any natural area were timber harvesting would be prevented. Both subpopulations exist as small number of scattered individuals and are entirely within the most conservative estimates of elevations that will be inundated by sea-level rise by 2100.
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 will likely result in the inundation of both locations (i.e., the entire population) by 2100 (Lendemer & Allen 2014, Sallenger et al. 2012)
Explanation of Proposed Rank. – This species merits ranking as Critically Endangered under multiple criteria. First it meets the criteria for Critically Endangered A3c based on the decline in AOO inferred from the projected inundation of both locations (100% of the population by 2100 as well as documented declines in habitat quality historically, at present, and projected into the future. Second it meets the criteria for Critically Endangered: B2a,b(i-v) based on the severly fragmented populations evidenced by the small number of documented subpopulations (two) both of which comprise small numbers (<25 each) of mature individuals, small AOO (8.000 km2), and projected loss of both individuals and habitat from inundation of both subpopulations by sea-level rise by 2100 . Third it meets the criteria for Critically Endangered C2a(i) based on the small number of total known mature individuals (<50), the projected and inferred declines discussed above, and the small number of mature individuals in each subpopulation (<25 each). Further, as a result of the small number of total mature individuals (<50 in two subpopulations) the species ranks as Critically Endangered D.
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 locations. Given the small number of populations, and the threats posed by sea-level rise, monitoring is also warranted. Translocation should also be considered before both subpopulations are lost to sea-level rise.
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 paucispora (common name: stingy spored lip lichen) is endemic to the Mid-Atlantic Coastal Plain of eastern North America where it occurs in low-lying swamp forests that are imperiled by sea-level rise and other forces.
Acanthothecis paucispora is known from two localities in the Chesapeake-Pamlico Lowlands and Tidal Marshes (Washington County) and Carolina Flatwoods (Jones County) Ecoregions of the Mid-Atlantic Coastal Plain of eastern North Carolina in eastern North America. Extensive fieldwork in the southeastern United States has failed to locate additional populations of the species.
Demographic studies are needed to assess and monitor populations sizes. Our current knowledge of the species suggests that its populations are stable.
Population Trend: Stable
This species occurs on the bark of hardwoods (specifically American holly (Ilex opaca) in well-developed mature forest stands. One population is from an unusual upland hardwood forest on a sand ridge that forms an ecotone with an extensive swamp forest. The other is from an unusual ox-bow swamp forest that forms an ecotone with a narrow fringe of mature hardwood forest.
The only known populations of this species occur 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, logging and other threats that would further degrade the 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.
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.