This is a key to all species of Cladoniaceae (Cladonia, Pilophorus and Pycnothelia) hitherto reported from Italy (see Nimis 2016, Burgaz & al. 2020), also including a few species known from neighbouring countries (see Nimis & al. 2018, Burgaz & al. 2020) which should be looked for in Italy, for a total of 88 infrageneric taxa.
Most of the species belong to Cladonia, a cosmopolitan genus of c. 470 species (Pino-Bodas & al. 2016). The phylogeny of the genus has been analysed by Stenroos & al. (2002), who proposed a new subgeneric classification and maintain the inclusion of Cladina into Cladonia (see also Stenroos & al. 1997, 2002b). The world distribution of several European species was treated by Litterski & Ahti (2004). Scandinavian species were monographed by Ahti & Stenroos (2013), Mediterranean species by Burgaz & al. (2020).
In spite of the fact that they are conspicuous and frequently collected, several species of Cladonia are chemically and/or morphologically very variable, and often poorly understood or misidentified. Some species which were accepted for a long time have been recently reduced to synonymy on the basis of molecular studies (see e.g. Pino-Bodas & al. 2010, 2015). The status of several species is still controversial, for example C. cryptochlorophaea, C. grayi, C. merochlorophaea and C. novochlorophaea are considered sometimes as chemical variations within one species. Here we provisionally follow Burgaz & al. (2020) in treating them as distinct species.
Some species groups can be reliably distinguished only on the basis of chemical characters (using TLC). The interpretation of the K reaction should be careful, since sometimes species with fumarprotocetraric acid only can react K+ faintly yellow/brown instead of K-. Particular care should be taken in using Paraphenylenediamine (P), a substance which is still widely used in hair dyes, but seems to be carcinogenic. Furthermore, sometimes old apothecia or pycnidia of red-fruited species can appear brownish or blackish; in such cases, chemical characters may help to achieve a correct identification. The sub-key to specimens without podetia includes only recognizable species which often have only the primary thallus, but all species of Cladonia, when young, may be devoid of podetia, and their identification at species level is often impossible without DNA data.

Acknowledgements: We are grateful to A. Aptroot and J. Moteiunajte for critical remarks on an earlier version of the key.

References

Ahti T., Stenroos S. 2013. Cladoniaceae. In: Ahti T., Stenroos S., Moberg R. (eds.) Nordic Lichen Flora Vol. 5. Museum of Evolution, Uppsala University, 117 pp.
Burgaz A.R., Ahti T., Pino-Bodas R. 2020. Mediterranean Cladoniaceae. Spanish Lichen Society (SEL), Madrid, ISBN: 978-84-09-21610-9, 117 pp.
Litterski B., Ahti T. 2004. World distribution of selected European Cladonia species. Symb. Bot. Upsal., 34: 205-236.
Nimis P.L. 2016. The lichens of Italy. A second annotated catalogue. EUT, Trieste, 740 pp.
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Stenroos S., Hyvönen J., Myllys L., Thell A., Ahti T. 2002. Phylogeny of the genus Cladonia s.lat. (Cladoniaceae, Ascomycetes) inferred from molecular, morphological, and chemical data. Cladistics, 18: 237-278.
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Last modified: February, 4, 2024

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