TAXONOMIC NOTES: Leptogium hibernicum Mitch ex P.M. Jørg. sensu stricto has an amphi-Atlantic distribution encompassing eastern North America and Western Europe. Specimens from South America, southwestern North America and New Zealand are reported to be part of a species complex of different clades (Stone et al. 2016, Bjelland 2017). The African specimens appear segregated into a separate evolutionary lineage and have been named Leptogium krogiae Bjelland, Frisch & Bendiksby. Even considering only northern hemisphere records, these are likely to encompass both L. hibernicum and the morphologically similar L. laceroides (Aragon et al. 2005, Anderson 2012), and some records in international databases probably represent the latter species.
The small, isolated, and widely-disjunct subpopulations of this epiphytic cyanolichen are restricted to areas of long ecological continuity in northern hemisphere, temperate, highly humid/hyperhumid, oceanic/montane areas of western Europe and wastern North America. This species is reported from 10 northern hemisphere countries. Over 40% of records come from the countries where the species has already been regionally assessed as threatened: listed as Near Threatened in Britain (Woods & Coppins, 2012) and Endangered in Norway (Bjelland and Ihlen, 2013). The subpopulation in Norway has been documented to have declined by 45% between 1995-2020. Climate change and poor habitat quality is forecast to cause losses in the UK, one of its population strongholds. Current losses and the climate change threat combine with declines forecast from the impacts of forestry in Canada and France, and a lack of new habitat. As the species also occurs on trees with a less acidic bark, it is susceptible to the decline of the European Ash (Fraxinus excelsior), which is under threat from an invasive fungus, Hymenoscyphus fraxineus. Future population reductions of 30-70% are estimated based on projecting current rates of decline forward over the next 90 years, with the lower estimate estimated based on direct losses to host trees from forestry, development and management changes and the higher figure suspected by adding the effects based on climate change forecasts. Threats are exacerbated by its low occurrence numbers and widely disjunct subpopulations. For these reasons, this species is listed as Endangered under criteria A3ce+4ace.
Assessor/s: Anderson, F. & Yahr, R., J.; Reviewer/s: Ellis, C. J. E.; Contributor/s: Acton, A., Bjelland, T., Gerault, A., López de Silanes , M., Masson, D., Matos, P., Perez-Ortega, S, Sanderson, N., Seaward, M.R.D.S. & Simkin, J.; Facilitator/s & Compiler/s: Allen, J.
Anderson, F. (2012) Reports of Leptogium hibernicum from the southern Appalachian Mountains, a major range extension for the species in North America. Opuscula Philolichenum11: 135-138.
Aragon, G., Otálora, M.A.G. & Martínez, I. (2005) New data on the genus Leptogium (lichenized ascomycetes) in the Iberian Peninsula. Nova Hedwigia80(1-2): 241-246.
Arvidsson, L. & Wall, S. (1985) Contribution to the lichen flora of Madeira. Lichenologist17(1): 39-49.
Berglund, H. & Jonsson, B.G. (2005) Verifying an extinction debt among lichens and fungi in northern Swedish boreal forests. Conservation Biology19: 338–348.
Bjelland, T. (2001) Comparative studies of the distribution and ecology of some oceanic species in the genus Leptogium (Lecanorales, Ascomycotina) in Norway. Nova Hedwigia72(1): 1-44.
Bjelland, T. & Ihlen, P.G. (2013) Utkast til faggrunnlag for irsk hinnelav (Leptogium hibernicum) i Norge. Rådgivende Biologer AS, Bergen.
Bjelland, T., Bendiksby, M. & Frisch, A. (2017) Geographically disjunct phylogenetic lineages in Leptogium hibernicum reveal Leptogium krogiae sp. nov. from East Africa. Lichenologist49(3): 239-251.
Seaward, M.R.D. (2010) Census catalogue of Irish lichens. National Museums Northern Ireland., Belfast.
Smith, C.W., Aptroot, A., Coppins, B.J., Fletcher, A., Gilbert, O.L., James, P.W. & Wolseley, P.A. (2009) The Lichens of Great Britain and Ireland. British Lichen Society, London.
Stone, D., Hinds, J.W., Anderson, F.L. & Lendemer, J.C. (2016) A revision of the Leptogium saturninum group in North America. Lichenologist48(5): 387-421.
Tingstad, L., Gjerde I., Dahlberg, A. & Grytnes, J. A. (2017) The influence of spatial scales on Red List composition: Forest species in Fennoscandia. Global Ecology and Conservation11: 247-297.
Urbanavichus, G., Vondrak, J., Urbanavichene, I., Palice, Z. & Malíček, J. (2020) Lichens and allied nonlichenized fungi of virgin forests in the Caucasus State Nature Biosphere Reserve (Western Caucasus, Russia). Herzogia33(1): 90-138.
Woods, R.G. & Coppins, B.J. (2012) A Conservation Evaluation of British Lichens and Lichenicolous Fungi. Species Status No. 13. JNCC, Peterborough.
Find out more about the IUCN Red List Categories and Criteriahere.
TYPE. IRELAND. Kerry, Killarney, Torc cascade, on mossy trees, 4.VIII.1933, G. Degelius s.n. (UPS, holotype).
Description. Lichenized fungus.
Thallus foliose, up to 5 cm diam., becoming markedly swollen when wet. Lobes 5–10 mm wide, overlapping with raised, rounded or partly dissected margins; swelling markedly when wet. Upper surface brownish or bluish gray, ± transversely wrinkled-striate. Vegetative diaspores isidia: coarse, nodular, in patches, or lobules developing along margins and on the surface. Lower surface paler, uniformly finely pubescent-tomentose; tomental hairs ~20 µm long with globose end cells. Photobiont Nostoc cyanobacteria; cells in chains. Apothecia not known.
Substrate and Habitat. Corticolous on trunks in sheltered forests.
Distribution. Amphi-atlantic; in North Carolina found in the Blue Ridge ecoregion.
Anderson, F. (2012) Reports of Leptogium hibernicum from the southern Appalachian Mountains, a major range extension for the species in North America. Opuscula Philolichenum11: 135-138
Gilbert, O.L. & P.M. Jørgensen. (2009) Leptogium (Ach.) Gray (1821). Pp. 541-551 in Smith, C.W., A. Aptroot, B.J. Coppins, A. Fletcher, O.L. Gilbert, P.W. James & P.A. Wolseley (eds.). The Lichens of Great Britain and Ireland. The British Lichen Society, London.