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  • Under Assessment
  • ENPreliminary Assessed
  • 4Assessed
  • 5Published

Scytinium apalachense (Tuck.) Otálora, P.M. Jørg. & Wedin

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Scientific name
Scytinium apalachense
(Tuck.) Otálora, P.M. Jørg. & Wedin
Common names
IUCN Specialist Group
Assessment status
Preliminary Assessed
Preliminary Category
EN A2; B2a,bi,ii,iv.v; C2ai
Proposed by
James Lendemer
James Lendemer, Jeremy Howland

Assessment Notes

Taxonomic notes

Scytinium apalachense is noted as an unusual cyanolichens due to its narrow almost 3-dimensional tube-shaped lobes and orange-yellow apothecia that stay immersed to slightly raised on its surface at maturity. Originally described as belonging to the morphologically similar genus Leptogium it was reclassified in a circumscription of the genus and placed under Scytinium (Otálora et al., 2014). The two genera differ in size, habitat, and distribution of their species. Confusion is common with Collema pustulatum and misidentifications between the taxa have been found in museum collections when reexamined (Lendemer & Harris, 2016).

Why suggested for a Global Red List Assessment?

Geographic range

The species is endemic to the temperature forested regions of eastern North America in Appalachian and Ozark Mountains and subsequent plateaus. However historical collections have been found at sites across the Mississippi River basin as far north as Minnesota (Wetmore, 2005). Modern collections (after 1994), however, have only confirmed its presence within these two mountainous regions.

Population and Trends

Scytinium apalachense is presumed extant at 14 sites based on fieldwork since 1994, with an area of occurrence (AOO) and Extent of Occurrences (EOO) of 56 km2 and 368,477 km2 respectively. There is a measured decline from 32 sites documented since 1955 to 14 known remaining presumed extant after 1994. The species has declined in EOO by 21% and AOO 53% over the last three generations. This decline corresponds to the loss of 18 sites, which are concentrated in the subpopulations outside of the core Appalachian and Ozark regions.

In the past 20 years the southern Appalachian and Ozark Mountains have been regions of intensive lichen floristic surveys, so records of this species there are likely reflective of the true distribution. We estimate an upper limit of 28 extant sites to account for lower sampling effort across the species entire range. Where it is documented to occur, it is noted as being rare (Minnesota Department of Natural Resources) and to consist of 10 or fewer functional individuals. However, no demographic study of the species or exhaustive targeted search for every individual exists at a single site. Due to lack of this research, we conservatively estimate 50 functional individuals at each site. Drawing from these calculations the population size of S. apalachense is inferred to be 1,400 functional individuals. Using the same population size estimate above for the extant population, we suspect the historical population to have comprised 3,200 functional individuals at 64 sites which suggests a 56% reduction in the number of mature individuals over the last three generations. 

In addition to the estimated decline in EOO, AOO and mature individuals, the areas of suitability are predicted to consist of small severally fragmented locations. These subpopulations are inferred to consist of presumed extant sites interconnected at distance of less than 100 km based on the dispersal limitation of the taxa (see Habitat & Ecology Summary). Six subpopulations are inferred to consist of no more than 250 individuals, with half being single sites with fewer than 50 individuals. Four of the subpopulations exist with the Ozark Mountain ranges and two in the southern Appalachians.

Population Trend: Decreasing

Habitat and Ecology

S. apalachense grows exclusively on shaded calcareous rock outcrops in temperate forested landscapes. Interestingly, although it grows in the same suitable habitat as C. pustulatum, the two species have never been collected from the same site (Lendemer & Harris, 2016). This lichen reproduces sexually by spores which are typically spread locally and rarely further by wind (Favero-Longo et al., 2014; Gjerde et al., 2015). However, these spores must associate with an appropriate photosynthetic partner (cyanobacteria) to successfully establish which limits long distance dispersal (Belinchón et al., 2015).

Temperate ForestRocky Areas [e.g. inland cliffs, mountain peaks]


Cyanolichens like S. apalachense are noted for being intolerant of disturbance and air pollution from human development (Sudirman et al. 2015). Structure changes to forest canopies through deforestation (logging and wood harvesting) are associated with declines in lichen diversity, especially cyanolichens (Richardson et al., 2004). Quarrying of limestone cliffs is a substantial threat in areas that are not conserved. Increasing urbanization is theorized to have eradicated the only known population in Minnesota where it’s been listed as endangered since 1984 but remains to be rediscovered (Minnesota Department of Natural Resources). Climate change throughout the southeastern United States is anticipated to increase extreme heat events, droughts and change forest composition that will likely impact the cool, moist, and protected microhabitats the species occupies (Wobus et al., 2018).

Housing & urban areasMining & quarryingUnintentional effects: subsistence/small scale (species being assessed is not the target) [harvest]Unintentional effects: large scale (species being assessed is not the target) [harvest]SmogHabitat shifting & alteration

Conservation Actions

Most localities where this species has persisted are already under some level of protection either federally or locally. These conservation actions, mostly within US National Forest Wilderness Areas and State Parks have sheltered this species from threats like urbanization and quarrying of suitable substrate. An increase in public awareness and education about the species will aid in long term monitoring, particularly training in how to identify the lichen and its site-specific habitat. Newly discovered occurrences should be considered for novel protection if not already established.

Site/area protectionSite/area managementFormal educationTraining

Research needed

Long term monitoring and scouting of suitable sites has been established in Minnesota and should be extended across the species historic range. Reexamination of all known sites, historic and extant, is necessary to collect demographic details to better assess population decline.

Population size, distribution & trendsPopulation trends

Use and Trade

The species is collected by scientists for use in research and biodiversity documentation.



Country occurrence

Regional Population and Trends

Country Trend Redlisted