The lichens of the Classical Karst (NE Italy-SW Slovenia): an interactive guide

Pier Luigi Nimis
Curator of the apparatus of images: Andrea Moro
This is a key to all lichens hitherto known from the Classical Karst Region (606 infrageneric taxa, including a few non- or doubtfully lichenized species traditionally treated by lichenologists). The key, which has been primarily prepared as a tool for lichenology labs at the University of Trieste, could be useful also outside the survey area, as it includes many widespread and common species.
The ‘Classical Karst’ (Italian: Carso; Slovenian: Kras) is a limestone plateau stretching NW to SE above the Gulf of Trieste, in the northernmost part of the Adriatic Sea, which is c. 40 Km long and up to 13 km wide, covering c. 440 Km2. Located part in Italy, part in Slovenia, it is delimited by the Adriatic Sea to the SW, the Friulian plain (river Soca/Isonzo) to the NW, the Vipava/Vipacco valley to the NE and by the Brkini hills (Flysch) and the Reka river valley to the SE, the SE limit being rather arbitrary. Although, strictly speaking, the Karst should be limited to areas with limestone, we have included in the study area the whole Province of Trieste, parts of which have Flysch as the main geological substrate.
Limestones and dolomites of cretaceous and tertiary origin predominate on the Plateau, reaching sea level in the northern part of the Province of Trieste, while the flanks of the Plateau are often covered with Flysch, an Eocenic alternation of sandstones and marl. Typical for the Plateau are the high rock solubility and the well-developed secondary porosity. Three main types of soils are present: Terra Rossa, Rendzina and Brown Cambisols. The climate is typically transitional between the Mediterranean type and the Central European type, with hot, rather dry summers and cold, rather rainy winters. Average annual precipitation ranges from c. 1000 mm along the coast to c. 1400 mm in the interior, with two maxima in June and November. Average annual temperatures range between 10.6 and 11.7°C. A very strong, cold wind from the NE, called Bora/Burja is rather frequent especially during winter, when the temperature difference between the coast and the interior are highest. The climatically transitional character of the Karst is reflected in sharp changes in flora and vegetation, corresponding to slight changes in microclimatic conditions, which explains the relatively high biodiversity of the area.
With the exception of a relict Mediterranean maquis in the northern part of the Province of Trieste, the potential vegetation is a temperate deciduous forest dominated by oaks. Since Neolithic times, however, the area was heavily deforestated due to intensive cattle-grazing, to the point that it was transformed into a kind of stony semi-desert interspersed with patches of dry grasslands. The sudden abandonment of cattle-grazing after the Second World War has produced a dramatic change in the vegetation, which now mainly consists of an open submediterranean woodland. The dry grasslands, among the floristically richest in Europe, are progressively disappearing, which implies a severe loss in biodiversity. The best preserved forests, dominated by oaks and Carpinus betulus, are located inside the deepest dolines, which are characteristic depressions with a marked thermic inversion.
The history of the lichenological exploration of the Karst area has been summarised by Nimis (1990, 1993, 2016), and Suppan & al. (2000). An important recent contribution is that by Wilfling & Mayrhofer (2003). The list of species derives from all papers cited in these works, plus unpublished records from the TSB Herbarium, and others kindly provided by H. Mayrhofer (in litt.). The total number of species included in the key is quite high for such a small, biogeographically and ecologically homogeneous area.

All images of species derive from the image archive of ITALIC (Nimis & Schumm 2019). We are grateful to all those who have provided pictures for the archive, which are mentioned in the metadata associated to each picture. The key has been produced using software FRIDA 3.0 (Martellos 2010, Martellos & Nimis 2015).
Currently, the interface is in the testing phase. It is published online to gather comments and corrections from users. We would be grateful for any feedback (please write to Prof. Pier Luigi Nimis -
How to use the key
Two query interfaces are available:
1) Dichotomous: this is a classical dichotomous key. The path to identification may be long, as the total number of species is high. At any step, you can obtain a textual key (incl. pictures) of the remaining species.
2) Multi-entry: This query interface allows you to specify a set of characters which fit those of your specimen: the result will be a dichotomous key including only the species which share these characters. If you already know the genus, you can also obtain a dichotomous key of all species of that genus (or you can combine the genus name with some other character: e.g. a key to all epiphytic species of Rinodina reacting K+ yellow).
1) Never use two different keys at the same time with the same browser: before using the second key, close the browser and start a new session.
2) If you want to start again the multi-entry interface, select ‘Key home page’ and re-launch the key.
3) When you use the multi-entry interface, select only characters which you are sure of. If you are in doubt, better leave the field empty.


Martellos S. (2010) Multi-authored interactive identification keys: The FRIDA (FRiendly IDentificAtion) package - Taxon, 59 (3): 922-929.
Martellos S. & Nimis P.L. (2015) From Local Checklists to Online Identification Portals: A Case Study on Vascular Plants. - PLoS ONE 10(3)
Nimis P.L. (1990) L’Erbario lichenologico dell’Università di Trieste (TSB). -- Not. Soc. Lich. Ital., 3, suppl. 1: 11-22.
Nimis P.L. (1993) The lichens of Italy. An Annotated Catalogue. - Mus. Reg. Sc. Nat. Torino, Monogr. XII, 897 pp.
Nimis P.L. (2016) The Lichens of Italy. A Second Annotated Catalogue. EUT, Trieste, 739 pp.
Nimis P.L. & Schumm F. (2019) ITALIC 5.0 - Images of lichens - Suppan U., Pruegger J, & Mayrhofer, H. (2000) Catalogue of the lichenized and lichenicolous fungi of Slovenia. - Bibl. Lichenol. 76, 215 pp.
Wilfling A. & Mayrhofer H. (2003) Contributions to the lichen flora of Slovenia IX. Lichenized and lichenicolous fungi from Crni Kal (Kras). - Stapfia 80: 293-310.

Last modified: July, 1, 2023