The genus Parmnotrema is characterised by foliose thalli forming short and broad, often ciliate lobes, an often pored epicortex, cylindrical to thread-like conidia, a usually wide bare marginal zone on the lower surface, and the intermediate type of lichenan between Cetraria- and Xanthoparmelia-types in the cortical cell walls (Hale 1965). Currently the genus comprises c. 300 species which occur mostly in the tropics, especially in the Pacific Islands and South America.
Recent molecular phylogenetic analyses of the lichen family Parmeliaceae have revealed that the members of the Parmelia crozalsiana-group form a sister clade to a clade containing members of the genus Parmotrema. The four species in this group were classified first in Parmelia, then in Pseudoparmelia, and later in Canoparmelia, until they were assigned to the newly created genus Crespoa (Lendemer & Hodkinson 2012). According to Kirika & al. (2016), however, they are best treated within a subgenus of Parmotrema. The genera Canomaculina, Concamerella, Rimelia, and Rimeliella were synonymised with Parmotrema by Blanco & al. (2005).
Seven species of Parmotrema are known to occur in Italy, all of them bound to rather humid microclimatic conditions (see Nimis 2016). The most common species is P. perlatum, the rarest are P. hypoleucinum and P. robustum, which are confined to a few undisturbed sites, mainly along the Tyrrhenian coasts.

References

Blanco O., Crespo A., Divakar P.K., Elix J.A., Lumbsch H.T. 2005. Molecular phylogeny of parmotremoid lichens (Ascomycota, Parmeliaceae). Mycologia, 97, 1: 150-159.
Hale M.E. 1965. A monograph of Parmelia subgenus Amphigymnia. Contr. U.S. natn. Herb. 36: 193-358.
Kirika P.M., Divakar P.K., Crespo A., Leavitt S.D., Mugambi G., Gatheri G.W., Lumbsch H.T. 2016. Polyphyly of the genus Canoparmelia uncovering incongruences between phenotype-based classification and molecular phylogeny within lichenized Ascomycota (Parmeliaceae). Phytotaxa, 289, 1: 36-48. Lendemer J.C., Hodkinson B.P. 2012. Recognition of the Parmelia crozalsiana group as the genus Crespoa. North Amer. Fungi, 7, 2: 1-5.
Nimis P.L. 2016. The Lichens of Italy. A Second Annotated Catalogue. EUT, Trieste, 739 pp.

Last modified: April, 24, 2024

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