Lecidella is a genus of the Lecanoraceae with c. 80 species worldwide, characterised by a crustose thallus with a trebouxioid photobiont, lecideine, dark-coloured apothecia with a persistent proper exciple of radiating, thick-walled hyphae, clavate, amyloid, eight-spored asci of the Lecidella-type, simple, hyaline, non-halonate ascospores, and curved, filiform conidia. Thallus chemistry, which is dominated by xanthones, has been the object of several detailed studies (e.g. Knoph 1990, Knoph & Leuckert 1994, 1997, 2000, Knoph & Schmidt 1995, Knoph & al. 1997, 2004). While the genus is well-defined, species delimitation is not always clear. In particular, the L. elaeochroma-complex, which includes some of the most common and widespread crustose epiphytic lichens of Italy, is still very poorly understood, as it is the saxicolous L. asema-complex. In Europe the knowledge of the genus would benefit from a thorough molecular analysis, as the one carried out mainly in China by Zhao & al. (2015).
The present key includes all infrageneric taxa known to occur in Italy (Nimis 2016), a few taxa which are known from neighbouring countries (see e.g. Nimis & al. 2018) and whose presence in Italy is possible, plus three species which were often considered as members of Lecidella but are now assigned to other genera (Carbonea latypizoides, Lecanora formosa, and Lecidea aemulans), for a total of 29 infrageneric taxa.

Acknowledgements: I am grateful to A. Aptroot for comments to an earlier version of the key.

References

Knoph J.G. 1990. Untersuchungen an gesteinsbewohnenden xanthonhaltigen Sippen der Flechtengattung Lecidella (Lecanorales, Lecanoraceae) unter besonderer Berücksichtigung von aussereuropäischen Proben exclusive Amerika. Bibl. Lichenol., 36, 1-183.
Knoph J.G., Leuckert C. 1994. Chemotaxonomic studies in the saxicolous species of the lichen genus Lecidella (Lecanorales, Lecanoraceae) in America. Nova Hedwigia, 59, 3-4: 455-508.
Knoph J.G., Leuckert C. 1997. Chemotypes and distribution patterns of the non-saxicolous species of Lecidella (Lecanoraceae, Lecanorales). Bibl. Lichenol., 68: 129-134.
Knoph J.G., Leuckert C. 2000. Chemotaxonomische Studien in der Gattung Lecidella (Lecanorales, Lecanoraceae). III. Die gesteinsbewohnenden Arten mit farblosem Hypothecium unter besonderer Berücksichtigung von europäischem Material Herzogia, 14: 1-26.
Knoph J.G., Leuckert C. 2004. Lecidella. In: T.H. Nash III & al.(eds), Lichen Flora of the Greater Sonoran Desert Region,vol. 2. Lichens Unlimited: Tempe,, pp. 309–320.
Knoph J.G., Leuckert C., Rittner W. 1997. Chemie und Verbreitung von Lecidella scabra (Taylor) Hertel & Leuck. Bibl. Lichenol, 67: 33-46.
Knoph J.G., Schmidt R. 1995. Untersuchungen einiger Arten der Gattung Lecidella mit Hochdruckflüssigkeitchromatographie unter besonderer Berücksichtigung von epiphytischen Proben. Bibl. Lichenol., 57: 307-326.
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.
Zhao X., Zhang L.L., Zhao Z.T., Wang E.C., Leavitt S.D., Lumbsch H.T. 2015. A Molecular Phylogeny of the Lichen Genus Lecidella Focusing on Species from Mainland China. PlosOne, 10,9: 1-13.

Last modified: August, 10, 2021

Project Dryades, Department of Life Sciences, University of Trieste - CC BY-SA 4.0