KEYS TO THE LICHENS OF ITALY - 92) EVERNIA (with Letharia, Lethariella and Pseudevernia)

Pier Luigi Nimis
This key, with 8 infrageneric taxa, includes all species occurring in Italy (Nimis 2016) of the following four genera of the Parmeliaceae:
Evernia Ach. - A small genus with c. 10 species, widespread in the Northern Hemisphere.
Letharia (Th. Fr.) Zahlbr. - This genus was earlier thought to comprise only a “species pair”: L. vulpina and L. columbiana, the former with abundant soredia, the latter with abundant apothecia. A molecular study by Högberg & al. (2002) found that the genus consists of at least six phylogenetic species, two that produce soredia, and four with ascomata. All 6 Letharia-species occur in western North America, L. vulpine and L. lupina being the only species found in Europe and North Africa, which, suggests that they originated in western North America and migrated to Europe. L. lupina, reported also from South Tyrol (Ament- Velásquez & al. 2021), is morphologically identical to L. vulpina and can be identified only by DNA-analysis.
Lethariella (Motyka) Krog - Species of this genus were formerly included within Usnea because of the more or less solid central axis of longitudinally arranged hyphae. In contrast to Usnea, which produces usnic acid, the species of Lethariella always contain atranorin. According to Obermayer (1997), both chemical and morphological differences might support the separation of subgenus Lethariella from the subgenera Chlorea and Nipponica, thus making Lethariella s.str., which includes the only species occurring in Italy, a monotypic genus.
Pseudevernia Zopf - A small genus including c. 5 species with a mostly temperate to boreal distribution. For the Italian distribution of the two chemical varieties see Martellos (2003).

Ament-Velásquez S.L., Touvinen V., Bergström L., Spribille T., Vanderpool D., Nascimbene J., Yamamoto Y., Thor G., Johannesson H. 2021. The plot thickens: haploid and triploid-like thalli, hybridization, and biased mating type ratios in Letharia. Frontiers in Fungal Biology, 2: 656386. DOI: 10.3389/ffunb.2021.656386
Högberg N., Kroken S., Thor G., Taylor J.W. 2002. Reproductive mode and genetic variation suggest a North American origin of European Letharia vulpina. Mol. Ecol., 11: 1191-1196.
Martellos S. 2003. The distribution of the two chemical varieties of the lichen Pseudevernia furfuracea in Italy. Plant Biosyst., 137, 1: 29-34.
Nimis P.L. 2016. The Lichens of Italy. A Second Annotated Catalogue. EUT, Trieste, 739 pp.
Obermayer W. 1997. Studies on Lethariella with special emphasis on the chemistry of the subgenus Chlorea. Bibl. Lichenol., 68: 45-66.

Last modified: February, 21, 2022