KEYS TO THE LICHENS OF ITALY - 15) CATAPYRENIUM and related genera (Anthracocarpon, Clavascidium, Heteroplacidium, Involucropyrenium, Neocatapyrenium, Placidium)

Othmar Breuss & Pier Luigi Nimis
This is a key to all catapyrenioid species (Anthracocarpon, Catapyrenium, Clavascidium, Heteroplacidium, Involucropyrenium, Neocatapyrenium, Placidium) known to occur in Italy (Nimis 2016). The key also includes several species which should be looked for in Italy, being known from the Iberian Peninsula or from the Alps outside Italy (see Nimis & al. 2018), for a total of 39 species.
After the monograph of Breuss (1990) on European species, the genus Catapyrenium was split into eight genera (Breuss 1996), based on combinations of characters such as the type of pycnidium, ascus shape and arrangement of the ascospores, colour of the excipulum, thallus anatomy and morphology (structure of the upper cortex and type of anchoring organs) and the presence/absence of an involucrellum. Seven genera occur in Italy:
1) Anthracocarpon Breuss - Anatomically resembling Placidium, but characterised by the presence of Endocarpon-type pycnidia, perithecia with a black to carbonaceous exciple (at least on the top), and rhizohyphae and rhizines as attachment organs (Breuss 1996). Of the three species reported worldwide, only one occurs in Europe.
2) Catapyrenium Flot. - This genus, which includes 6 species, was submitted to a molecular phylogenetic analysis by Prieto & al. (2010), who confirmed its separation from Placidiopsis. The species of the Iberian Peninsula were treated by Prieto & al. (2010b).
3) Clavascidium Breuss - This genus was synonymised with Placidium by Gueidan & al. (2009), but since it forms a monophyletic clade and can be differentiated by the presence of rhizines (which, however, are sometimes difficult to observe), it was accepted by Prieto & al. (2012). The genus, as re-circumscribed by Prieto & al. (2012), includes 5 species and is characterised by the presence of rhizines and clavate to (sub-)cylindrical asci. C. semaforonense, the only species of the genus with marginal pycnidia, is distantly related to the rest of species with laminal pycnidia.
4) Heteroplacidium Breuss – A segregate from Placidium including c. 9 species characterised by clavate asci, biseriate ascospores and a less differentiated thallus anatomy, growing on soil and rock in warm-temperate regions. The close molecular relationship of Heteroplacidium and Placidium found by Prieto & al. (2012) is in accordance with the traditional, morphologically and anatomically based classification. Although both genera are very closely related, molecular data support their distinction as monophyletic entities, with a few minor taxonomic adjustments.
5) Involucropyrenium Breuss - This still poorly known genus was separated from Catapyrenium, which has the same type of upper cortex, by the position of the perithecia, situated between the squamules, and the presence of an involucrellum. The genus, which includes 8 species, is distributed mainly in Europe, with a single species present in North America and Asia. The species occur on calcareous and gypsiferous soils, in rock fissures or directly on limestone, sometimes also on old bricks or mortar, in semi-arid to alpine and temperate environments.
6) Neocatapyrenium Breuss -The species have a cushion-like thallus composed of imbricate squamules, anatomically similar to that of Placidium, but characterised by Endocarpon-type pycnidia with cylindrical conidia, the lack or reduction of rhizohyphae and the attachment to the substratum by rhizines or by the basal end of the squamules; the perithecia have a colourless exciple, the asci are clavate with biseriate ascospores. There are 5 species reported worldwide, 3 of which are present in Europe. For further details see Breuss (1996).
7) Placidium A. Massal.- This genus with c. 28 species, is characterised by marginal or laminal pycnidia and the absence of rhizines. It is closely related to Heteroplacidium, but molecular data support the distinction of the two genera as monophyletic entities.
A worldwide key to catapyrenioid species was published by Breuss (2010), a key to W-European species by Roux (2005), and a key to those of the Iberian peninsula by Prieto & al. (2010b). On the whole, the identification of these species is not easy, especially when poorly developed material only is available; Important characters are the anatomy of the thallus, the form of the asci, and the position of the pycnidia (which are often lacking) on the squamules. Consequently, the entire group is poorly known, and Italian material is well worthy of a thorough revision.


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Last modified: April, 10, 2022