Pier Luigi Nimis
Responsible for the apparatus of images: Andrea Moro - Management of software and databases: Stefano Martellos

The taxonomy of Teloschistaceae is presently in a state of flux and high confusion, with different authors proposing different generic arrangements. In a recent revision of the Xanthorioideae, Kondratyuk et al. (2014) accepted no less than 31 genera for this group only (97 genera for the whole Family). Here I follow the much less extreme splitting proposed by Arup & al. (2013), although I admit that by having every single species into a monospecific genus we would reach nomenclatural stability. The paper by Arup et al. (2013) is the most comprehensive attempt of a re-definition of the Teloschistaceae based on molecular data. The traditional circumscription of Xanthoria has been profoundly modified, with the segregation of several species into other genera, such as Polycauliona, Rusavskia and Xanthomendoza (see Arup & al. 2013). In its narrower definition, Xanthoria is a well-supported genus of c. 10 species, including the slightly deviating X. resendei. The genus is best represented in the Northern Hemisphere, with an obvious diversity centre in the Mediterranean area. Polycauliona, as re-defined by Arup & al. (2013) is a rather large (c. 25 species) genus consisting of some smaller-sized foliose and fruticose species formerly included into Xanthoria, together with crustose species. Xanthomendoza was originally monotypic, until Søchting et al. (2002) transferred all Xanthoria-species with rhizines and bacilliform conidia to Xanthomendoza. Afterwards, the genus was once again made monotypic when all these species were transferred to Oxneria (Kondratyuk and Karnefelt 2003), a separation which was not generally accepted (see e.g. Lindblom 2006).
In spite of their showy appearance, Xanthorioid lichens are still rather poorly known in Europe, and especially in the Mediterranean region, with several species which would require further study. Here – pending molecular analysis of original material of Xanthomendoza huculica - I follow Lindblom et al. (2019) in treating X. huculica as a synonym of X. fallax. The key includes the 19 infrageneric taxa known to occur in Italy.
I am grateful to U. Arup (Lund), M. Grube and W. Obermayer (Graz), who provided material regarding Rusavskia hafellneri. The key is presently under revision by L. Lindblom (Bergen).

References .

Arup U., Søchting U., Frödén P. 2013. A new taxonomy of the family Teloschistaceae. Nord. J. Bot., 31: 16-183.
Kondratyuk S., Kärnefelt I. 2003b. Revision of three natural groups of xanthorioid lichens (Teloschistaceae, Ascomycota). Ukrayins’kyi Bot. Zhurn. 60: 427–437.
Kondratyuk S.Y., Kärnefelt I., Thell A., Elix J.A., Kim J.A., Jeong M.H., Yu N.H., Hur J.S. 2014. A revised taxonomy of the subfamily Xanthorioideae (Teloschistaceae, Ascomycota) based on molecular phylogeny. Acta Bot. Hung., 56.
Lindblom L. 2006. Xanthomendoza galericulata, a new sorediate lichen species, with notes on similar species in North America. Bryologist, 190: 1-8.
Lindblom L., Blom, H.H., Timdal E. 2019. The genus Xanthomendoza in Norway. Graphis Scripta, 31(7): 54–75.
Sochting U. et al. 2002. Revision of Xanthomendoza (Teloschistaceae, Lecanorales) based on morphology, anatomy, secondary metabolites and molecular data. Mit. Inst. Allg. Bot. Hamburg 30-32: 225–240.

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