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ASSESSMENT JUSTIFICATION [criteria: A3ce; B1ab(iii)+2ab(iii)]

Mycoporum biseptatum is endemic to high elevations in the southern Appalachian Mountains of eastern North America. It grows on shrubs in disjunct northern hardwood forests and globally unique, endangered spruce-fir forests. The narrow distribution, small area of occupancy (AOO; 24-192 km2), small number of locations (6-48), and threats to the ecosystems in which it lives, which include invasive species, climate change, resource extraction and recreation, all contribute to the vulnerable status of the species. A decline of at least 30% in population size is suspected to occur within the next 36 years (three generations). Therefore, it is assessed as Vulnerable under criterion A3c, and precautionarily under criterion B1ab(iii)+2ab(iii) too.

Assessor/s: Lendemer, J.; Reviewer/s: Allen, J.

Bibliography:

Allen, J.L., & Lendemer, J.C. (2016) Climate change impacts on endemic, high-elevation lichens in a biodiversity hotspot. Biodiversity Conservation 25: 555–568.

Degelius, G N. (1941) Contributions to the Lichen flora of North America II. The lichen flora of the Great Smoky Mountains. Arkiv för Botanik 30A: 1-80.

IUCN (2021) The IUCN Red List of Threatened Species. Version 2021-2. Available at: www.iucnredlist.org. (Accessed: 04 September 2021).

Lendemer, J.C. & Harris, R.C. (2014) Studies in lichens and lichenicolous fungi—No. 18: resolution of three names introduced by Degelius and Magnusson based on material from the Great Smoky Mountains. Castanea 79(2): 106-117.

Find out more about the IUCN Red List Categories and Criteria here.

TYPE. UNITED STATES. North Carolina, Swain County, Great Smoky Mountains National Park, Forney Ridge, 1760 m, on Viburnum alnifolium, 13.IX.1939, G. Degelius s.n. (UPS L-68873, holotype).

Description. Semi-lichenized fungus.

Thallus endophloedal to absent. Photobiont rare or absent, trentepohlioid alga; cells 10.5-13.0 µm, membrane thick or thin. Ascomata compound perithecia, black, flattened, resembling small apothecia, 0.2-0.4 mm diam., immersed. Perithecial wall apical, brownish black, 10-15 μm thick; hymenium hyaline to yellowish, 45-65 μm high; paraphyses branched-anastomosing, 1-1.5 μm thick. Asci ventricose (pear-shaped), 35-52 x 23-30 μm with a thick outer wall, 8-spored. Ascospores hyaline, narrowly ovoid wtih blunt tips, 3-celled, constricted at septa, 20-25 x 6.5-8.5 μm. Pycnidia frequent, immersed, black, 50-70 μm.

Substrate and Habitat. Corticolous on fast-growing, smooth bark of shrubs and small trees in high elevation forests.

Distribution. Endemic to southern Appalachian Mountains of eastern North America; in North Carolina found in the Blue Ridge ecoregion.

Notes. This species’ current name was initially published as a nomenclatural combination with the basionym Arthonia biseptata Degel. as “Mycoporum biseptatum (Degel.) Lendemer & R.C Harris” (Lendemer & Harris 2014).  It was since learned that the basionym was an illegitimate homonym of the earlier A. biseptata Vain. from Brazil, so Lendemer & Harris (2015) republished M. biseptatum as a replacement name for A. biseptata Degel., dropping the “(Degel.)” from the author portion of the current name.

Literature

Degelius, G.N. (1941) Contributions to the Lichen flora of North America II. The lichen flora of the Great Smoky Mountains. Arkiv för Botanik 3: 1-80 (original description as Arthonia biseptata).

Lendemer, J.C. & R.C. Harris. (2014) Studies in Lichens and Lichenicolous Fungi – no. 18: resolution of three names introduced by Degelius and Magnusson based on material from the Great Smoky Mountains. Castanea 79(2): 106-117.

Lendemer, J.C. & R.C. Harris. (2015) A nomenclatural note on Mycoporum biseptatum (basionym Arthonia biseptata). Opuscula Philolichenum 14: 116-117.