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Acanthothecis leucoxanthoides Lendemer

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Scientific name
Acanthothecis leucoxanthoides
Author
Lendemer
Common names
 
IUCN Specialist Group
Lichens
Kingdom
Fungi
Phylum
Ascomycota
Class
Lecanoromycetes
Order
Ostropales
Family
Graphidaceae
Assessment status
Published
Assessment date
2017-08-30
IUCN Red List Category
CR
IUCN Red List Criteria
B2ab(ii,iii,v); C2a(i); D
Assessors
Lendemer, J. & Allen, J.
Reviewers
Scheidegger, C.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/80702763/80702766

Justification

This species merits ranking as Critically Endangered based on the small number of documented locations (2) both of which comprise a small number of individuals (less than 25 in each), low area of occupancy (8 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  based on the small population (less than 50 mature individuals) the small number of individuals in each subpopulation (two subpopulations each with less 25 individuals). Further the species also ranks as Critically Endangered based on the overall small size of the population which is estimated to be less than 50 mature individuals.

Geographic range

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.

Population and Trends

Two populations have been documented and are presumed to be extant. Both populations are small in size comprise less 25 individuals each (for a total of less 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.

Population Trend: stable


Habitat 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). This species occurs on the bark of hardwoods in a remnant rich hardwood (Liriodendron, Acer, Magnolia, Nyssa) and cypress (Taxodium). Despite extensive inventories by multiple specialists of suitable habitats throughout the region over a period spanning more than 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, the populations potentially non-viable and so the population is precautionarily assessed as severely fragmented.


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).


Conservation Actions

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. 


Source and Citation

Lendemer, J. & Allen, J. 2018. Acanthothecis leucoxanthoides. The IUCN Red List of Threatened Species 2018: e.T80702763A80702766. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T80702763A80702766.en .Accessed on 31 January 2022

Country occurrence