KEYS TO THE LICHENS OF ITALY - 6) XANTHOPARMELIA (with ARCTOPARMELIA)
Pier Luigi Nimis, Paolo Giordani
Responsible for the apparatus of images: Andrea Moro - Management of software and databases: Stefano Martellos

The genus Xanthoparmelia comprises more than 800 species worldwide, with the highest diversity in semi arid-areas, mostly on siliceous rocks. Originally, the genus included only the greenish-yellow species with usnic/isousnic acids in the upper cortex, while similar species with brown thalli were placed in the genus Neofuscelia. Molecular studies have shown that the latter genus is polyphyletic, with clades scattered within Xanthoparmelia. Consequently, the species of Neofuscelia are now included in Xanthoparmelia (Blanco & al. 2004b). The species concept in this genus is still open to discussion: according to Nimis (2016), all too many chemical strains were raised to the rank of species. Matteucci & al. (2017) studied the morphological and chemical variability at the local scale, finding a high number of morpho-chemotypes, with several metabolites showing a rather continuous variability that was often related to macro- and micronutrient contents in thalli, which suggests that environmental influence may complicate variability patterns in Xanthoparmelia. Some authors (e.g. Roux & coll. 2014) tend to subsume several chemical taxa at the level of variety or chemical form without taxonomic recognition. Pending further molecular analyses, we still accept them here at species level. In Italy the genus has been monographed by Giordani et al. (2002, 2003), and 19 species are presently known from Italy.
The present key also includes the 2 Italian species of the genus Arctoparmelia. This mainly arctic-boreal genus of 5 species is characterised by a sparse development of rhizines. Although the yellow-green thalli are reminiscent of some Xanthoparmelia-species, morphological and molecular analyses support a position in the hypogymnioid clade of the Parmeliaceae (Wei & al. 2015).

References

Blanco O., Crespo A., Elix J.A., Hawksworth D.L., Lumbsch H.T. 2004. A new classification of parmelioid lichens containing Xanthoparmelia-type lichenan (Ascomycota: Lecanorales) based on morphological and molecular evidence. Taxon, 53, 4: 959-975.
Giordani P., Nicora P., Rellini I., Brunialti G., Elix J.A. 2002b. The lichen genus Xanthoparmelia (Ascomycotina, Parmeliaceae) in Italy. Lichenologist, 34, 3: 189-198.
Giordani P., Benesperi R., Rellini I., Frati L., Brunialti G., Paoli L., Isocrono D., Elix J.A. 2003. The lichen genus Neofuscelia (Ascomycota, Parmeliaceae) in Italy. Lichenologist, 35, 5-6: 377-386.
Matteucci E., Occhipinti A., Piervittori R., Maffei M., Favero-Longo S.E. 2017. Morphological, secondary metabolite and ITS (rDNA) variability within usnic acid containing lichen thalli of the genus Xanthoparmelia explored at the local scale of rock outcrop in Western Italian Alps Chemistry & Biodiversity 14, 6: 1-15.
Nimis P.L. 2016. the Lichens of Italy. A second annotated Catalogue. EUT, Trieste, 739 pp.
Roux C. & coll. 2014. Catalogue des lichens et champignons lichénicoles de France métropolitaine. Henry des Abbayes, 1525 pp.
Wei X.-L., Chen K., Lumbsch H.T., Wei J.-C. 2015. Rhizines occasionally occur in the genus Hypogymnia (Parmeliaceae, Ascomycota). Lichenologist, 47, 1: 69-75.