KEYS TO THE LICHENS OF ITALY - 55) PANNARIOID LICHENS (Pannariaceae, Gregorella, Massalongia and Vahliella)
Pier Luigi Nimis & Per Magnus Jørgensen
Apparatus of images: Andrea Moro - Software and databases: Stefano Martellos

After the classical monograph of the Pannariaceae by Jørgensen (1978), the circumscription of the family and of several genera has been considerably modified, due to recent molecular work (see later). The present key includes all species which in the past were considered as members of the Pannariaceae that are known to occur in Italy (Nimis 2016), plus a few species which are known from neighbouring countries (see e.g. Nimis & al. 2018), and which should be looked for in Italy, for a total of 26 species.
Species from the following genera are included in the key:
1) Fuscopannaria P.M. Jørg. - This genus of c. 50 species was separated from Pannaria on account of the hemiamyloid hymenium, the asci with an amyloid apical ring-structure, and the production of fatty acids and terpenoids, but not pannarin. In addition, most species are small-squamulose and form apothecia with a variably developed thalline margin. The genus is widespread in mainly cool-temperate areas of the Northern Hemisphere, and has two evolutionary centres: one in the northern Pacific and adjacent regions in America, and the other in Asia, mainly in Pacific North America and East Asia. The systematic position of the genus within the Pannariaceae has been treated by Ekman (2014b). The genus Moelleropsis, after the transfer of one of its two species to Gregorella, became monotypic; molecular studies indicate that the type species, M. nebulosa, is nothing but a very specialised Fuscopannaria (Jørgensen 2007, Ekman & al. 2014b).
2) Gregorella Lumbsch - This monotypic genus was recently established by Lumbsch & al. (2005) to accommodate a species which was placed in the formerly monotypic Moelleropsis by Coppins & Jørgensen (in Purvis & al. 1993). But while the type species of Moelleropsis proved to be a member of Fuscopannaria in the Pannariaceae (see later), the other species proved to be very distant from all other Pannariaceae (Ekman & Jørgensen 2002, Wedin & al. (2005). A molecular study by Lumbsch & al. (2005) proved that the species belongs instead in the Arctomiaceae.
3) Massalongia Körb. - This genus includes 3 species, 2 of which occur in temperate to subarctic regions of the Northern Hemisphere, on acid rocks or amongst mosses. Because of its apothecia, the genus was for a long time believed to belong to the Pannariaceae (even if the ascospores are septate), but molecular data support its inclusion in the Peltigerinae (Jørgensen 2007). Wedin & al. (2007) showed that, together with Polychidium and Leptochidium, it forms a well-supported monophyletic group which is characterised by both molecular and morphological data; the three genera, which have a similar hemiangiocarpic ascoma ontogeny where only a few “cover cells” are produced, similarly built apothecia, and similar asci with an amyloid apical cap, are now placed in the Massalongiaceae (Wedin & al. 2007).
4) Nevesia P.M. Jørg., L.Lindblom, Wedin & S. Ekman - A monospecific genus which is not known with mature apothecia, with an Atlantic-Mediteranean distribution, not known from outside Europe (Ekman & al. 2014).
5) Pannaria Bory - The first genus to be recognized among the Pannariaceae and the origin of the family name, including c. 50 species with a squamulose or foliose thallus, apothecia with a thalline margin, an amyloid hymenium, asci without internal amyloid apical structures, and the presence of pannarin and related substances. Most species are distributed in warm-temperate regions, with the notable exception of P. hookeri, which is arctic-alpine. For further details see Ekman & al. (2014).
6) Parmeliella Müll. Arg. - This widespread, mainly warm-temperate to subtropical genus, was originally established for squamulose members of the Pannariaceae with apothecia lacking a thalline margin. In later treatments it was restricted to species with an amyloid apical ring structure in the asci and a lack of lichen substances in the thallus. Even after the separation of Degelia and Pectenia, Parmeliella remained heterogeneous. After the segregation of several species by Ekman & al. (2014), Parmeliella can be retained as a monophyletic entity. In this circumscription, it is a mostly temperate genus of small-squamulose species, generally without chemical substances and apothecia without a thalline margin, but with an amyloid hymenium producing asci with an internal apical tube structure.
7) Pectenia P.M.Jørg., L.Lindblom, Wedin & S. Ekman - This genus with a most characteristic, thick, shell-like thallus was excluded from Parmeliella by Jørgensen & James (1990) and referred to as a subgenus of the Southern Hemisphere genus Degelia. Molecular studies, however, showed it to be a separate genus, restricted to the Northern Hemisphere, with most species in wet temperate parts of Europe and one disjunct occurence in Eastern North America. In Europe, species delimitation is still an open problem: four species were accepted, based on minute morphological characters (see e.g. Cannon & al. 2021), but the molecular study by Otálora & al. (2017) revelead the existence of only two, morphologically variable species.
8) Protopannaria (Gyeln.) P.M.Jørg. & S.Ekman - This genus of the Pannariaceae includes 7 crustose-squamulose species without secondary chemistry, apothecia with thalline margin, and amyloid hymenia with asci lacking internal amyloid structures. The only species occurring in Italy has an arctic-alpine distribution. For further details see Ekman (2014b).
9) Psoroma Michx. - In the traditional taxonomy of the Pannariaceae, all green algal species of the family were included in Psoroma, with the exception of two species assigned to Psoromidium. After the segretation of Psorophorus, Xanthopsoroma (Elvebakk & al. 2010), and Gibbosporina (Elvebakk & al. 2016), the current circumscription of Psoroma s.str. includes squamulose to small-squamulose lichens with green algae as the main photobiont, ascomata with a distinct thalline margin, tube-like apical amyloid ascus structures, and mostly no secondary medullary substances. The genus, which is still heterogeneous, includes c. 25 species, most of which have a circum-Antarctic distribution, the 3 European species having an arctic-alpine distribution.
10) Staurolemma Körb. - This small genus with 3 species, one of which occurs in temperate Europe, was considered as a member of the Collemataceae until recent molecular phylogenetic studies indicated that the gelatinous thallus structure was not a synapomorphy of a monophyletic group (Wedin & al. 2009; Otálora & al. 2010). Most of the gelatinous taxa with septate ascospores formed a distinct group (Collemataceae s.str.), while the genera with simple ascospores, such as Staurolemma, were shown to belong to a different family within the same order, the Pannariaceae.
11) Vahliella P.M.Jørg. - This genus was described to accommodate the former subgenus Micropannaria of Fuscopannaria. Currently, it includes 8 species in cool-temperate areas of the Northern Hemisphere, with the highest diversity in North America. Molecular studies have shown that Vahliella differs so much from Fuscopannaria that it cannot even be placed in the Pannariaceae, the family Vahliellaceae having being recently segregated within the suborder Peltigerinae (Wedin & al. 2011).

References

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Elvebakk A., Robertsen E.H., Park C.h., Hong S.G. 2010. Psorophorus and Xanthopsoroma, two new genera for yellow-green, corticolous and squamulose lichen species, previously in Psoroma. Lichenologist, 42, 5: 563-585.
Elvebakk A., Hong S.G., Park C.H., Robertsen E.H., Jørgensen P.M. 2016. Gibbosporina, a new genus for foliose and tripartite, palaeotropic Pannariaceae species previously assigned to Psoroma. Lichenologist, 48, 1: 13-52.
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