The genus Micarea, formerly assigned to its own family, the Micareaceae, and presently included in the Pilocarpaceae, includes more than 100 species, and occurs on all continents, including Antarctica. The phylogeny of the Micareaceae was studied by Andersen & Ekman (2005) using mitochondrial ribosomal DNA sequences. The family proved to be highly heterogeneous, and Helocarpon, Psilolechia, and Scutula, thought to be close relatives of Micarea, proved to be only distantly related. Andersen & Ekman (2005) suggested to reduce the Micareaceae to synonymy with the Pilocarpaceae,a family which also includes the Ectolechiaceae. The genus Micarea itself proved to be paraphyletic, unless the entire Pilocarpaceae and Ectolechiaceae are included: besides the likely assignment of several species to other genera, such as Helocarpon, at least three different taxa are involved:
1) Brianaria S. Ekman & M. Svenss., including the former Micarea bauschiana-aggregate, with so far 4 species known from the Northern Hemisphere, which is characterised by a chlorococcoid (non-micareoid) photobiont, small, convex apothecia without an exciple, asci of the Psora-type, 0-1-septate ascospores, dimorphic paraphyses, and immersed pycnidia containing bacilliform conidia. Brianaria forms a monophyletic group in the Psoraceae, where it is probably the sister group to Psora and Protoblastenia.
2) Leimonis R.C. Harris, a genus of the Pilocarpaceae with so far 2 species, which differs from Micarea s.str. in the well-developed proper exciple and the chlorococcoid (not micareoid) photobiont,
3) Micarea s.str. Fr., forming a complex, partly unresolved clade comprising the remaining species.
In Europe, Micarea, as traditionally delimited, was monographed by Coppins (1983) and further studied at a smaller scale by Coppins (2009) for Great Britain and Ireland, and Czarnota (2007) for Poland. Recently, the study of micareoid lichen has again attracted the attention of lichenologists, due to the production of molecular sequences and phylogenetic reconstructions that have revealed a much greater diversity then previously recognized, more than 20 species having been recently described (e.g. for Europe: Coppins & Tonsberg 2001; Czarnota 2007; Czarnota & Guzow-Krzemińska 2010; Guzow-Krzemińska & al. 2016, 2019; Myllys & Launis 2018; Launis & Myllys 2019; Launis & al. 2019a,b; Sérusiaux & al. 2010; Svensson & Thor 2011; van den Boom & Ertz 2014; van den Boom & Coppins 2001; van den Boom & al. 2017, 2020). Species delimitation has been especially difficult in the M. prasina-group which was first characterised by Coppins (1983) based on morphological, anatomical and chemical features.
Micarea is still poorly known in Italy, a country where the optimal ecological conditions for the genus (humid climate, acid substrata) are quite localized. The present key includes all species formerly treated as members of Micarea in the past (incl. Brianaria, Helocarpon, Leimonis, Protomicarea and Psilolechia), which were reported from Italy, plus several species which are known from neighbouring countries in the Alps (see Nimis & al. 2018), for a total of 52 infrageneric taxa. Several recently-described, semi-cryptic species in the M. prasina-group, which are known only from western, northern and central Europe are not included, although the presence of some of them in Italy cannot be excluded; for those, we refer to the key by Kantelinen & al. (2021).

References

Andersen H.L., Ekman S. 2004. Phylogeny of the Micareaceae inferred from nrSSU DNA sequences. Lichenologist, 36, 1: 27-35.
Andersen H.L., Ekman S. 2005. Disintegration of the Micareaceae (lichenized Ascomycota): a molecular phylogeny based on mitochondrial rDNA sequences. Mycol. Res., 109, 1: 21-30.
Coppins B.J. 1983 A taxonomic study of the lichen genus Micarea in Europe. Bull. British Mus. Nat. Hist., Botany ser. 11, 2: 17-214.
Coppins B.J. 2009. Micarea. In: Smith C.W. & al. (Eds.) The Lichens of Great Britain and Ireland. British Lichen Society, London, pp. 583-606.
Coppins B.J., Tønsberg T. 2001. A new xanthone-containing Micarea from Northwest Europe and the Pacific Northwest of North America. Lichenologist, 33, 2: 93-96.
Czarnota P. 2007. The lichen genus Micarea (Lecanorales, Ascomycota) in Poland. Polish Bo¬t. Studies, 23: 1-199.
Czarnota P., Guzow-Krzemińska B. 2010. A phylogenetic study of the Micarea prasina group shows that Micarea micrococca includes three distinct lineages. Lichenologist, 42, 1: 7-21.
Guzow-Krzemińska B., Czarnota P., Łubek A., Kukwa M. 2016. Micarea soralifera sp. nov., a new sorediate species in the M. prasina group. Lichenologist, 48, 3: 161-169.
Guzow-Krzemińska B., Sérusiaux E., van den Boom P.P.G., Brand A.M., Launis A., Łubek A., Kukwa M. 2019. Understanding the evolution of phenotypical characters in the Micarea prasina group (Pilocarpaceae) and descriptions of six new species within the group. MycoKeys, 57: 1-30.
Kantelinen A., Westberg M., Owe-Larsson B., Svensson M. 2021. New Micarea records from Norway and Sweden and an identification key to the M. prasina group in Europe. Graphis Scripta, 33, 2: 17-28.
Launis A., Myllys L. 2019. Micarea fennica, a new lignicolous lichen species from Finland. Phytotaxa, 409: 179-188.
Launis A., Pykälä J., van den Boom P., Sérusiaux E., Myllys L. 2019a. Four new epiphytic spe¬cies in the Micarea prasina group from Europe. Lichenologist, 51, 1: 7-25.
Launis A., Malícek J., Sérusiaux E., Svensson M., Tsurykau A., Myllys L. 2019b. Sharpening spe¬cies boundaries in the Micarea prasina group with notes on the type species M. prasina. Mycologia, 111, 4: 574-592.
Myllys L. Launis A. 2018. Additions to the diversity of lichens and lichenicolous fungi living on decaying wood in Finland. Graphis Scripta, 30, 6: 78-87.
Nimis P.L. 2016. The lichens of Italy. A second annotated catalogue. EUT, Trieste, 740 pp.
Nimis P.L., Hafellner J., Roux C., Clerc P., Mayrhofer H., Martellos S., Bilovitz P.O. 2018. The Lichens of the Alps. An Annotated Catalogue. MycoKeys, 31: 1-634.
Sérusiaux E., Brand A.M., Motiejūnaitè J., Orange A., Coppins B.J. 2010. Lecidea doliiformis belongs to Micarea, Catillaria alba to Biatora and Biatora ligni-mollis occurs in Western Europe. Bryologist, 113: 333-344.
Svensson M., Thor G. 2011. Micarea capitata, a new bryophilous lichen from Sweden. Li¬chenologist, 43, 5: 401-405.
van den Boom P.P.G., Coppins B.J. 2001. Micarea viridileprosa sp. nov., an overlooked lichen species from Western Europe. Lichenologist, 33, 2: 87-91.
van den Boom P.P.G., Ertz D. 2014. A new species of Micarea (Pilocarpaceae) from Madeira growing on Usnea. Lichenologist 46, 3: 295-301.
van den Boom P.P.G, Brand A.M., Coppins B.J., Sérusiaux E. 2017. Two new species in the Micarea prasina group from Western Europe. Lichenologist, 49, 1: 13-25.
van den Boom, P.P.G., Guzow-Krzemińska B., Kukwa M. 2020. Two new Micarea species (Pilocarpaceae) from Western Europe. Plant and Fungal Syst., 65, 1: 189-199.

Last modified: July, 30, 2023

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