The genus Placynthiella Elenkin (Coppins & James 1984, Coppins & al. 1987), in the Trapeliaceae, includes 7 species growing on acidic substrata (see e.g. Tønsberg 1993), and is characterised by a crustose, granular-verrucose thallus consisting of goniocysts (clumps of algae with an outer layer of brown-walled, pseudoparenchymatous hyphae), biatorine to lecideine apothecia with a pseudoparenchymatous exciple, a dark brown epihymenium and hypothecium, Trapelia-type asci with 8, mostly simple ascospores, and branched paraphyses with dark, apically swollen tips.
This key includes the 5 species which are known to occur in Italy (Nimis 2016).

References

Coppins B.J.. James P.W. 1984. New or interesting British lichens V. Lichenologist, 16: 241-264.
Coppins B.J., James P.W., Hawksworth D.L. 1987. The generic names Placynthiella Elenkin, Saccomorpha Elenkin and Placynthiella Gyelnik. Lichenologist, 19: 93-95.
Nimis P.L. 2016. The lichens of Italy. A second annotated catalogue. EUT, Trieste, 740 pp.
Tønsberg T. 1992. The sorediate and isidiate, corticolous, crustose lichens in Norway. Sommerfeltia 14: 1-331.

Last modified: July, 24, 2021

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