The lichens of the Alps - an annotated checklist

In the history of biogeography, the Alps play a most important role: they are one of the largest continuous natural areas in Europe, and probably the most studied mountain system worldwide, to the point that terms such as “alpine” and “subalpine” are widely used for any mountain system in the world.
Situated between the Eurosiberian and the Mediterranean biogeographic regions, the Alps are an interzonal mountain system distributed among seven countries over an area of c. 170,000 km2, with a length of c. 1,200 km and a maximum width of 300 km; they start at sea level and peak at 4,807 m (Mt. Blanc). The Alps are present in eight countries: Austria (28.7 % of the overall area of the Alps), Italy (27.2%), France (21.4 %), Switzerland (13.2 %), Germany (5.8 %), Slovenia (3.6 %), Liechtenstein (0.08%), and Monaco (0.01%) with a total population of c. 11.1 million people. The Alps, which include fourteen national parks and many regional protected areas, shelter a large number of natural and semi-natural habitats, with a rich diversity of organisms and landscapes. They are one of the richest biodiversity hotspots in Europe, hosting e.g. 4,450 vascular plant taxa with a density of 2,200 taxa per 10,000 km² (Aeschimann et al. 2011a), the most species-rich areas being in the West and the South, the richest in endemics corresponding to areas that were glacier-free during the Pleistocene, such as the southern part of the Western Alps, and the Eastern Alps (Tribsch 2004, Aeschimann et al. 2011b).
The Alps are also the mountain system which was explored with more continuity by botanists, zoologists and mycologists, including lichenologists. It is not easy for present readers to imagine the problems facing the first scholars in studying the lichens of the Alps: neither highways nor rapid trains brought to the Alpine region, and any ascension to the Alpine belt had to be paid with days of travel through dusty or muddy roads and of hard climbing through paths built by shepherds, with uncomfortable overnight stays in primitive shelters with limited food, finally carrying down the heavy collections to the next village. In spite of these difficulties, the Alps have been intensively studied since the earliest years by important lichenologists such as, to mention only a few, M. Anzi (1812-1881), F. Arnold (1828-1901), F. Baglietto (1826-1916), S. Garovaglio (1805-1882), Ph. Hepp (1797-1867), A. M. Hue (1840-1917), E. Kernstock (1852-1900), A. von Krempelhuber (1813-1882), A. Massalongo (1824-1860), W. Nylander (1822-1899), J. Müller Argoviensis (1828-1896), A. E. Sauter (1800-1881), L. E. Schaerer (1785-1853), G. A. Scopoli (1723-1788), E. Stizenberger (1827-1895), and F. X. von Wulfen (1728-1805). In the second half of the XIX Century, the first attempts of national-regional checklists appeared, such as those of Krempelhuber (1861) for Bavaria, Stizenberger (1882, 1883) for Switzerland, and Jatta (1900) for Italy. In the XX Century, the lichenological exploration of the Alps continued and intensified to the present times, especially from the post World War II period, when important Masters such as Georges Clauzade (1914-2002), Eduard Frey (1888-1974), and Josef Poelt (1924-1995) contributed to a revival of lichenological studies in the Alps by training a new generation of lichenologists, including most authors of the present checklist.
Thus, the Alps are, beyond doubt, one of the lichenologically best investigated parts of the world. Surprisingly, however, no general overview of their lichen diversity was ever attempted, all of the existing checklists having being compiled at the national or regional levels, a situation which also applies to most of the other taxonomic groups, including animals, and to most transnational orobiomes worldwide, with the notable exception, for lichens, of the Carpathian mountains (Bielczyk et al. 2004, Lisická 2005). This lack of a general overview hampered the possibility of comparing the biogeographic traits of such an emblematic area as the Alps with those of other mountains systems worldwide, including not only other European orobiomes (Carpathians, Pyrenees, Scandinavian Mts., Caucasus) but also extra-European ones (Himalayas, Rocky Mountains, tropical high mountains of Africa, New Zealand Alps, etc.), to elucidate various patterns of disjunctions and overall distribution, both on the taxonomic level (species, genera) and on that of entire biota. This fact is particularly annoying in the case of lichens, which include many broad-ranging species and relatively few endemics, so that many taxa described from the Alps have been later detected in other parts of the world.
Work for the present checklist started almost 15 years ago, upon a suggestion by P.L. Nimis. The idea was to rapidly produce a catalogue of lichens known from the Alps, by electronically merging the information contained in the checklists of Germany (Grummann 1963, Scholz 2000), Italy (Nimis 1993), Austria (Türk and Poelt 1993, Hafellner and Türk 2001), Slovenia (Suppan et al. 2000), and Switzerland (Clerc 2004, at that time in preparation), plus those included in the still unpublished catalogue of the lichens of France by C. Roux and collaborators. A first general list was produced in 2005, but its completion proved to be much less easy than foreseen, mainly because of the many open taxonomic problems, and the necessity of continuous updates due to intense lichenological exploration in most countries. The progress of lichenological activity in several “Alpine” countries was such, that in the last few years, new, updated checklists were published for Switzerland (Clerc and Truong 2012), France (Roux et coll. 2014, 2017), Italy (Nimis and Martellos 2003, Nimis 2016), Germany (Wirth et al. 2013), and Austria (Hafellner and Türk 2016).
The present checklist tries to summarise all of this information, providing, for the first time, a complete annotated catalogue of all lichenised fungi hitherto reported from the Alps.

Delimitation of the Alps
In planning a checklist of the Alps we had to face the question of delimiting the corresponding geographic area. As there is no unique delimitation of the Alps, we have adopted one approaching the boundaries proposed by Marazzi (2005), within which Aeschimann et al. (2004) only retained the Alpine phytogeographic unit. However, we point to some differences: 1) contrary to Aeschimann et al. (2004), in the Western Alps our limits extend to sea level, also encompassing areas with an eu-Mediterranean vegetation, and the coastal rocks along the Mediterranean Sea. 2) Monaco is included; however, to our knowledge, there is no lichen record from this small country (c. 2 km2), which is practically devoid of natural areas. 3) Contrary to Marazzi (2005), we included the Mt. Salève range as e.g. did Führer (1979), who drew the border of the Alps along the Rhine and therefore had regarded it as part of the Bornes Alpes. Despite geological similarities with the Jura, Mt. Salève is much closer to the Alps, and lichens described from there may well occur in the adjacent, equally mainly calcareous Massif de Bornes. 4) We have also included the area of Trnovsky Gozd in Slovenia, which is considered sometimes as part of the Alps (e.g. by Bätzing 2001, 2015), sometimes of the Dinarides (e.g. by Marazzi 2005).
Alpine and pre-Alpine Slovenia were delimited according to the phytogeographic units proposed by Wraber (1969) and Zupančič et al. (1987), because of the lack of suitable administrative subdivisions in the young country when we started preparing the checklist. With the exception of Slovenia, the further subdivision of the Alpine area into Operational Geographic Units correspond with those of the main administrative units (Bundesländer in Austria, Départements in France, Regierungsbezirke in Germany/Bavaria, Regioni in Italy, Cantons in Switzerland), because this is the way the records are organised in the national lichen checklists.
Fig. 1 - Delimitation of the Alps, with the administrative subdivisions (for abbreviations, see below)

In several cases, the adopted delimitation of the Alps does not correspond with the limits of the administrative subdivisions; typical is the case of Liguria (Italy), where only a very minor part of the regional territory falls within the Alpine area. In such cases, we have tried, as far as possible, to eliminate from the regional lists all species which occur in these regions, but have no record from the Alpine area proper.

Structure of the checklist
The list is mainly based on records published in the recent checklists of Slovenia (Suppan et al. 2000, integrated by Mayrhofer 2006), Switzerland (Clerc and Truong 2012), Germany (Grummann 1963, Scholz 2000, Wirth et al. 2013), France (Roux et coll. 2014, 2017), Italy (Nimis 2016), and Austria (Hafellner and Türk 2016). We refer to these works for a more extensive list of references and/or further details on the data sources. The data concerning Liechtenstein derive from a still unpublished work by Hafellner and Boom (in prep.). In a few cases, floristic and taxonomic treatments published after the national checklists were also taken into consideration. Several non-lichenised species which were and are traditionally treated by lichenologists are included, but non-lichenised lichenicolous fungi are excluded.

Nomenclature and synonyms
We have tried to update nomenclature to the latest standards. However, we have preferred to maintain some old, well-established genera such as Caloplaca and Aspicilia, since too many species from the Alps still await a re-assignment to the new genera in which they were split, mainly on the basis of molecular data. Apart from the basionyms, we include well-established synonyms used in publications about lichens in the Alps, but due to space limitations we do not include an index of all cited names. Such a thesaurus will be included in a forthcoming online version of the checklist.

Lichenised and non-lichenised species
L - Lichenised species.
F - Non- or doubtfully lichenised species usually reported by lichenologists.

Poorly known taxa
# - This checklist includes quite a high number of very poorly understood taxa, often only known from the type material. We have decided to retain most of them, for the following reasons: 1) They could constitute good taxa, as it is happening for some of the many species of Verrucariaceae described by M. Servít, 2) They could prove to be the correct name for other taxa described later, 3) In some cases their oblivion was mainly due to the unavailability of the type material, which was recently discovered and awaits further study (e.g. for some of the taxa described by M. Anzi, see Nimis 2016).

Substrates (Subs.)
The main types of substrates are abbreviated as follows:
sil - siliceous rocks and corresponding man-made substrata (e.g. roofing tiles),
cal - calciferous rocks and corresponding man-made substrata (e.g. concrete, cement, asbestos etc.),
int - intermediate rocks (such as calciferous schists),
met - metal-rich siliceous rocks,
sax - rocks (without more detailed information),
ter-cal - calciferous soil,
ter-sil - acidic soil (mostly on siliceous substrata),
bry - living mosses,
deb - plant debris,
cor - bark,
xyl - lignum,
fol - living leaves,
res - resin,
alg - living algal colonies,
par - parasitic on other lichens,
aqu - temporary or permanently submerged.

Bioclimatic/Altitudinal distribution (Alt.)
1 - Mesomediterranean belt (potential vegetation: evergreen broad-leaved forests dominated by Quercus ilex),
2 - Submediterranean/colline belt (potential vegetation: mixed deciduous forests dominated by Quercus and Carpinus),
3 - Montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies,
4 - Subalpine belt (potential vegetation: open, taiga-like forests dominated by Larix decidua and/or Pinus cembra and Rhododendron),
5 - Alpine (potential vegetation: treeless Alpine grasslands and tundras, to the lower limit of perennial snow and the equilibrium line of glaciers),
6 - Nival (as before, above the lower limit of perennial snow and glaciers).

Regional distribution
For each infrageneric taxon, we report the presence in the 7 Alpine countries and in 42 Operational Geographic Units, corresponding to their main subdivisions. Particularly dubious records are flagged with “?”. In the very few cases of records from a country without specification of locality, we repeat the abbreviation of that country.
Austria (Au): V - Vorarlberg, T - Tirol, S - Salzburg, K - Kärnten, St - Steiermark, O - Oberösterreich, N - Niederösterreich (incl. Wien), B - Burgenland.
Germany (Ge): OB - Oberbayern, Schw - Schwaben.
Switzerland (Sw): AP - Appenzell, BE - Bern, FR - Fribourg, GL - Glarus, GR - Graubünden, LU - Luzern, SG - St. Gallen, SZ - Schwyz, TI - Ticino, UR - Uri, UW - Unterwalden, VD - Vaud, VS - Valais.
France (Fr): in brackets the number designing each Departement in the French administrative system. AHP - Alpes-de-Haute-Provence (04), HAl - Haute-Alpes (05), AMa - Alpes-Maritimes (06), Drô - Drôme (26), Var - Var (83), Isè - Isère (38), Sav - Savoie (73), HSav - Haute-Savoie (74), Vau - Vaucluse (84).
Italy (It): Frl -Friuli (excluding the Province of Trieste), Ven - Veneto, TAA - Trentino-Alto Adige, Lomb - Lombardia, Piem - Piemonte, VA - Valle d'Aosta, Lig - Liguria (limited to the westernmost part of the region).
Slovenia (Sl): SlA - Alpine and Pre-Alpine Slovenia, Tg - Trnovsky Gozd.
Liechtenstein (Li).

The notes to each taxon briefly describe its main ecology and distribution. For poorly known taxa we have often added a brief description, in order to help the reader understanding what the name may refer to. For obvious reasons of space, in the notes we have refrained to cite any literature, except the national checklists on which the present catalogue is based. We refer to those for more detailed literature citations.

Databasing the checklist
The present checklist has been converted into a freely searchable database within a month from its publication in paper-form. The database include a searchable thesaurus of synonyms, which will compensate the fact that, for reasons of space, this paper-printed version is not provided with an alphabetical index of the thousands of names included in the text.

The lichen diversity of the Alps: some numbers
The present checklist includes, not considering the taxa mentioned in the appendix and excluding the dubious records, 3,163 infrageneric taxa, 3,009 of which are certainly lichenised. The number of poorly known taxa is quite high (604, 19% of the total), which indicates that much work is needed to reach a satisfactory picture of the real lichen diversity of the Alpine system.
The number of infrageneric taxa known for the different countries and their subdivisions, only their “Alpine” areas being considered, is as follows:
Austria (2,337 infrageneric taxa): V - Vorarlberg (1,249), T - Tirol (1,704), S - Salzburg (1,495), K - Kärnten (1,525), St - Steiermark (1,670), O - Oberösterreich (1,001), N - Niederösterreich (1,194), B - Burgenland (280).
Italy (2,169): Frl -Friuli (1,022), Ven - Veneto (1,160), TAA - Trentino-Alto Adige (1,562), Lomb - Lombardia (1,298), Piem - Piemonte (1,282), VA - Valle d'Aosta (793), Lig - Liguria (722).
France (2,028): AHP - Alpes-de-Haute-Provence (1,056), HAl - Haute-Alpes (788), AMa - Alpes-Maritimes (1,392), Drô - Drôme (363), Var - Var (841), Isè - Isère (747), Sav - Savoie (858), HSav - Haute-Savoie (1,062), Vau - Vaucluse (848).
Germany (1,168): OB - Oberbayern (942), Schw - Schwaben (630).
Switzerland (1,835): AP - Appenzell (51), BE - Bern (960), FR - Fribourg (147), GL - Glarus (305), GR - Graubünden (1,206), LU - Luzern (609), SG - St. Gallen (238), SZ - Schwyz (873), TI - Ticino (697), UR - Uri (655), UW - Unterwalden (467), VD - Vaud (598), VS - Valais (1,191).
Slovenia (890): SlA - Alpine and Pre-Alpine Slovenia (843), Tg - Trnovsky Gozd (346).
Liechtenstein (152).
The number of taxa is well in agreement with the percentage of the Alpine area occupied by the various countries. Comparing the smaller OGUs is quite difficult, considering that they vary considerably in surface areas, geomorphological heterogeneity, and degree of conservation of local ecosystems. In general terms, however, the richest areas are located in the Eastern Alps, such as Tyrol (1,704 taxa), Steiermark (1,670), Trentino-Alto Adige (1,562), and Kärnten (1,525), while, even considering their mostly smaller surface areas, several OGUs located in the Western Alps, especially in Switzerland and in France, and those in Germany and in Slovenia, would need a more intense lichenological exploration.

Concluding Remarks
Checklists summarise in a more or less critical way the hitherto known information on the biodiversity of a given group of organisms in a given area. They can have different nature, scope and contents, and they should be always judged considering the situation of floristic and taxonomic research that they reflect. Obviously, not all literature records can be accepted uncritically: the circumscription of taxa may differ among authors, recent taxonomic revisions might have shown that a given taxon actually includes several taxa of the corresponding rank, some authors may be more reliable than others, etc. The author of a checklist is often forced to make difficult decisions, since in most cases it is not possible to check directly all identifications cited in the literature. Checklists might differ also on account of the degree of exploration of the area they cover. In the case of poorly explored areas they just summarise the current state of knowledge, but cannot pretend to be exhaustive. For well-explored areas one could think that they do not only represent a basis for future updates, but also a kind of prodromus for a true Flora. This, however, is not the case of the present checklist. The idea that the degree of taxonomic knowledge parallels that of floristic exploration, i.e. that in well-studied areas most infrageneric taxa are likely to be relatively well-delimited taxonomically, proved to be basically wrong. Our checklist includes many long-forgotten names referring to very poorly understood taxa, often only known from the type collection, which are in need of critical revision. Thus, the total number of taxa accepted in this checklist does not reflect the actual species diversity of the Alps, due to inadequate taxonomic knowledge. Incidentally, further taxonomic research will often reduce rather than increase the number of accepted taxa. The citation of these names in the checklist is, however, important, because it will bring these potentially correct names, often published in long-forgotten papers, to the attention of specialists. For this reason we also transferred a number of species to genera to which they most likely belong, in order to increase the probability of their inclusion in future critical revisions.
Checklists are never-ending ventures, subject to continuous updating following the developments of current research. We hope that the present checklist will prove to be a valuable tool for retrieving and accessing the enormous amount of information on the lichens of the Alps which has accumulated during centuries of research, offering a basis for specimen revision, for the critical re-appraisal of poorly-known taxa, and for the further exploration of under-investigated areas, becoming a catalyst for new, more intensive investigations. The best criterion for a checklist to have accomplished its task as a facility to the scientific community is the speed of its becoming outdated (Nimis 2016), which is what we paradoxically wish to the present one.