The genus Placopyrenium in the Verrruariaceae was established by Breuss (1987) to include species formerly placed in Dermatocarpon with placodioid thalli and areoles fixed to the substrate by stipe-like holdfasts. The circumscription of the genus has been subsequently enlarged to include species without black-rimmed areoles as well as lichenicolous ones, formerly treated as Dermatocarpon and Catapyrenium (see Breuss 2009) plus two members of the Verrucaria fuscella group (Navarro-Rosines & al. 2007). Currently the genus contains c. 22 species characterised by an areolate to subsquamulose thallus, immersed perithecia with a reduced or missing involucrellum, colourless, simple or 1-(-2)-septate ascospores, and pycnidia of the Dermatocarpon-type. A general key was published by Breuss (2009). For further details see also Gueidan & al. (2009) and Orange (2013). A detailed description of P. bucekii was provided by Ménard & Roux (1995).
The present key includes all species known to occur in Italy (Nimis 2016), plus 4 species which are known from neighbouring countries in the Alps and should be looked for in Italy (Nimis & al. 2018), for a total of 8 species. Two further species described from Italy, which likely belong to this genus but are not included in the key being very poorly known, are Dermatocarpon gorzegnoense Servít, which is known only from the type material (Piedmont), and Placidiopsis crassa (Anzi) Clauzade & Cl. Roux, which is probably related to, if not identical with, Placopyrenium formosum Orange (see Orange 2009).

References

Breuss O. 1987. Placopyrenium. In: Nimis P.L. & Poelt J.: The lichens and lichenicolous fungi of Sardinia (Italy). Studia Geobotanica, 7, Suppl. 1: 182–183.
Breuss O. 2009. A synopsis of the lichen genus Placopyrenium (Verrucariaceae), with descriptions of new taxa and a key to all species. Bibl. Lichenol., 99: 93-112.
Gueidan C., Savi S., Thüs H., Roux C., Keller Ch., Tibell L., Prieto M., Heiðmarsson S., Breuss O., Orange A., Fröberg L., Amtoft Wynns A., Navarro-Rosinés P., Krzewicka B., Pykälä J., Grube M., Lutzoni F. 2009. Generic classification of the Verrucariaceae (Ascomycota) based on molecular and morphological evidence: recent progress and remaining challenges. Taxon, 58, 1: 184-208.
Ménard T., Roux C. 1995. Placopyrenium bucekii et remarques sur les Verrucariaceae (Verrucariales, Lichenes). Mycotaxon, 53 : 129-159. Navarro-Rosinés P., Roux C., Gueidan C. 2007. La genroj Verrucula kaj Verruculopsis (Verrucariaceae, Verrucariales). Bull. Soc. linn. Provence, 58: 133-180.
Nimis P.L. 2016. The Lichens of Italy. A Second Annotated Catalogue. EUT, Trieste, 739 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.
Orange A. 2009. Two parasitic species of Placopyrenium (Verrucariaceae) from freshwater habitats in north-west Europe. Lichenologist, 41, 2: 131-139.
Orange A. 2013b. British and Other Pyrenocarpous Lichens. Vers. II. August 2013. https://museum.wales/.../Orange-A-2013-British-and-other-pyrenocarpous-lichens.pdf

Last modified: August, 21, 2024

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