Assessment Notes

Justification

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 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 mean that the species is considered to occur in a single threat  location. Acanthothecis paucispora is therefore assessed here as Critically Endangered.

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Geographic range

Acanthothecis paucispora is a rare script lichen known from two localities in the Mid-Atlantic Coastal Plain of southeastern North America.

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Population and Trends

Two subpopulations have been documented and are presumed to be extant. Both populations are small and composed of less than 25 mature individuals (i.e., total population is estimated at less than 50 mature individuals). One sub-population is included within Croatan National Forest, although not within a wilderness area or other management sub-unit that would afford additional protections. The other sub-population is located in a protected unit managed by North Carolina State University, however that sub unit is not currently part of any natural area where timber harvesting would be prevented. Both sub-populations 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. 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

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Habitat 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, yet no additional sub-populations 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 more than 20 years, no additional sub-populations have been located. While it is possible that additional sub-populations will be located in the future, thus expanding the AOO and EOO, the available data clearly illustrates that the species is rare.

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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 localities (i.e., the entire population) by 2100 (Lendemer & Allen 2014, Sallenger et al. 2012).

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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 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.
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.

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Source and Citation

Lendemer, J. & Allen, J. 2018. Acanthothecis paucispora. The IUCN Red List of Threatened Species 2018: e.T80702772A80702775. Accessed on 21 November 2025.

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