The genus Heppia, including c. 7 species (4 of which are known from Italy, see Nimis 2016) occurring on soil in arid environments, forms a well-supported monophyletic entity differing from most members of the Lichinaceae only in the subgelatinous, corticate thallus with a vertical hyphal arrangement, and an ascoma primordium consisting of strictly vertically oriented generative hyphae (Schultz & Büdel 2003). The genus has been monographed in Europe by Egea (1989). The apparently similar genus Gloeoheppia, included into the Gloeoheppiaceae, differs from Heppia in the small, squamulose to moderately peltate thalli, the reticulately branched hyphae with cylindrical or roundish cells surrounding the colonies of the small-celled cyanobiont, and the presence of interstices and cavities in the thallus. It currently includes 5 species, one of which is known from Italy, occurring on calcareous substrata, mostly on soil, in arid and semi-arid regions of the Northern Hemisphere.

References

Egea J.M. 1989. Los géneros Heppia y Peltula (Liquenes) en Europa Occidental y Norte de Africa. Bibl. Lichenol, 31.
Nimis P.L. 2016. The Lichens of Italy. A Second Annotated Catalogue. EUT, Trieste, 739 pp.
Schultz M., Büdel B. 2003. On the systematic position of the lichen genus Heppia. Lichenologist, 35, 2: 151-156.

Last modified: december, 4, 2021

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