This is a key to all species of fruticose and foliose Physciaceae of Italy, including 67 infrageneric taxa belonging to 10 genera:
1) Anaptychia Körb. - Characterised by spores of Physconia-type and a prosoplechtenchymatous upper cortex, which includes c. 15 species worldwide. It is a sister group to Physconia and appears to be monophyletic. For further details see Esslinger (2007) and Lohtander & al. (2008).
2) Heterodermia Trevis. - In the traditional circumscription, this was a subcosmopolitan genus with c. 100 species, most diverse in warm-temperate to subtropical and tropical regions, mainly in the Southern Hemisphere. A recent phylogenetic study by Mongkolsuk & al. (2015) retains Heterodermia only for species with a lower cortex and Pachysporaria-type ascospores (without sporoblastidia), while the other species are segregated in the new genera Leucodermia Kalb, with foliose to subfruticose, linear-elongate, ribbon-like, dichotomously branched and loosely attached lobes without a lower cortex and Polyblastidium-type ascospores (with sporoblastidia), and Polyblastidium Kalb, with a foliose thallus attached to the substrate, no lower cortex and mostly Polyblastidium-type ascospores. The remaining species are assigned to groups without a formal generic name, awaiting further study, the H. comosa-group, and the H. obscurata-group that contains species with a cottony-woolly lower surface which is impregnated by anthraquinones. These results were confirmed by Diaz-Escandon & Lücking (2016) in Colombia, who found that the H. obscurata-group was supported as sister to Heterodermia s.str., both closely related to Polyblastidium, and the H. comosa-group, sister of Leucodermia. A study by Lücking & al. (2008) showed that the use of both medullary chemistry and underside pigmentation for the distinction of species is supported, which is in contrast to concepts used in some recent treatments of the genus.
3) Hyperphyscia Müll. Arg. - This genus of c. 9 species, with the highest diversity in tropical and temperate regions (see e.g. Moberg 2004), is distinguished from other small-foliose Physciaceae by the filiform rather than bacilliform conidia and by the absence of atranorin in the upper cortex. Whether the conidia can be maintained as a diagnostic character remains to be determined, given the demonstrated polyphyletic nature of Amandinea, which also possesses filiform conidia.
4) Leucodermia Kalb - See Heterodermia.
5) Phaeophyscia Moberg - Mainly characterised by the ellipsoid conidia and the absence of atranorin, comprises c. 30 species with a mainly temperate to tropical distribution in both Hemispheres, and is particularly well represented in the submediterranean areas of Europe.
6) Physcia (Schreb.) Michx. - A well-defined cosmopolitan genus which includes c. 80 species, characterised by the bacilliform conidia and the presence of atranorin. The P. aipolia-P.caesia complex has been studied by Myllys & al. (2001) and Lothander & al. (2009), who showed that neither taxon is monophyletic, and that an independent taxonomic status should be assigned to some controversial morphotaxa.
7) Physciella Essl. - A small genus including 4 species which differ from Physcia in the lack of atranorin, and from Phaeophyscia in the paraplectenchymatous lower cortex. The distinction between Physciella and Phaeophyscia is not acceped by all authors, but seems to be confirmed by molecular data (Figueras & Hladun 2009).
8) Physconia Poelt - This genus, with c. 25 species, was proposed to accommodate the section Pulverulentae of Physcia s.lat. on the basis of spore characters. Initially it was thought to have the centre of diversity in the Mediterranean area, but subsequent studies in North America and Asia have shown a broader distribution. A molecular phylogenetic study (Cubero & al. 2004) supports Physconia as a monophyletic group most closely related to Anaptychia. Divakar & al. (2007) showed that P. distorta and the European populations identified as P. americana form two monophyletic species and that both are distinct from the true, strictly American P. americana, which led to the description of a new species (P. thorstenii) for Europe.
9) Polyblastidium Kalb - See Heterodermia.
10) Tornabea Østh. - This monotypic fruticose genus has a remarkably disjunct distribution in semi-arid areas of both Hemispheres (see Nimis & Tretiach 1997).

References

Cubero O.F., Crespo A., Esslinger T.L., Lumbsch H.T. 2004. Molecular phylogeny of the genus Physconia (Ascomycota, Lecanorales) inferred from a Bayesian analysis of nuclear ITS rDNA sequence Mycol. Res., 108, 5: 498-505.
Diaz Escandon D., Lücking R. 2016. Heterodermia Trevis. in Colombia: New insights into generic divisions within Heterodermia sensu lato. IAL 8, Book of Abstracts, Helsinki: 160.
Divakar P.K., Amo de Paz G., Del Prado R., Esslinger T.L., Crespo A. 2007. Upper cortex anatomy corroborates phylogenetic hypothesis in species of Physconia (Ascomycota, Lecanoromycetes). Mycol. Res., 111, 11: 1311-1320.
Esslinger T.I. 2007. A synopsis of the North American species of Anaptychia (Physciaceae). Bryologist, 110, 4: 788-797.
Figueras G., Hladun N.L. 2009. La confirmacion molecular del género Physciella (Physciaceae). XVII Symp. Bot. Crypt., Lisboa, Livro de Resumos: 129.
Lohtander K., Ahti T., Stenroos S., Urbanavichus G. 2008. Is Anaptychia monophyletic? A phylogenetic study based on nuclear and mitochondrial genes. Ann. Bot. Fenn., 45: 55-60.
Lohtander K., Myllys L., Källersjö M., Moberg R., Stenroos S., Tehler A. 2009. New entities in Physcia aipolia-P. caesia group (Physciaceae, Ascomycetes): an analysis based on mtSSU, ITS, group I intron and betatubulin sequences. Ann. Bot. Fenn., 46: 43-53.
Lücking R., del Prado R., Lumbsch H.T., Will-Wolf S., Aptroot A., Sipman H.J.M., Umaña L., Chaves J.L. 2008. Phylogenetic patterns of morphological and chemical characters and reproductive mode in the Heterodermia obscurata group in Costa Rica. Systematics and Biodiv., 6, 1: 31-41.
Moberg R. 2004. Notes on foliose species of the lichen family Physciaceae in southern Africa. Symb. Bot. Upsal. 8, 1: 257-288.
Mongkolsuk P., Meesim S., Poengsungnoen V., Buaruang K., Schumm F., Kalb K. 2015. The lichen family Physciaceae in Thailand. II. Contributions to the genus Heterodermia sensu lato. Phytotaxa, 235, 1: 1-66.
Myllys L., Lohtander K., Tehler A. 2001. B-tubulin, ITS and group I intron sequences challenge the species pair concept in Physcia aipolia and P. caesia. Mycologia 93, 2: 335-343.

Last modified: July, 12, 2024

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