Received: 23 August 2017 Revised: 16 May 2018 Accepted: 17 May 2018 H) Check for updates DOI: 10.1111/avsc.l2386 VEGETATION SURVEY Applied Vegetation Science Revision of the central Mediterranean xerothermic cliff vegetation Massimo Terzi1 | Nenad Jasprica2 | Danka Cakovic3 | Romeo Di Pietro4 institute of Bioscience and Bioresources, CNR, Bari, Italy institute for Marine and Coastal Research, University of Dubrovník, Dubrovník, Croatia 3Department of Biology, Faculty of Science, University of Montenegro, Podgorica, Montenegro 4Department of Planning, Design and Technology of Architecture, Section Environment and Landscape, Sapienza University of Rome, Rome, Italy Correspondence Massimo Terzi, Institute of Bioscience and Bioresources, CNR, via Amendola 165, 1-70126 Bari, Italy. Email: massimo.terzi@ibbr.cnr.it Co-ordinating Editor: Florian Jansen Abstract Questions: What are the syntaxonomic and synchorological patterns of the xerothermic chasmophytic vegetation in the central part of the Mediterranean Basin? What are the diagnostic species of the high-rank syntaxa of Asplenietalia glandulosi, Onosmetalia frutescentis and Centaureo dalmaticae-Campanuletalia pyramidalis? Location: Mediterranean coastal and subcoastal areas of southern France, Italy, Malta, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania and of mainland Greece. Methods: The data set of 1,261 published releves was analysed using hierarchical clustering (Flexible Beta method), involving a series of data transformations. Indicator species analysis was used to select the best dendrogram solution and identify diagnostic taxa of the main clusters. The dendrogram was interpreted from a syntaxonomic point of view, using nomenclatural type releves as a basis. The NMDS ordination was performed in order to visualize the floristic relationships among associations and high-rank syntaxa. MRPP was used to test for differences among alliances. Results: The classification revealed four main clusters of releves representing the chasmophytic vegetation of southern France, Sardinia and the northwestern part of Italy (Asplenienalia glandulosi/Asplenietalia glandulosi), the southwestern part of Italy and Malta (Tinguarrenalia siculae/Asplenietalia glandulosi), the Adriatic Basin area (Centaureo dalmaticae-Campanuletalia pyramidalis) and the southern Balkans (Onosmetalia frutescentis). The NMDS ordination confirmed the overall pattern, while MRPP showed significant differences among the alliances of the above-mentioned orders and suborders. The lists of diagnostic taxa of the high-rank syntaxa were revised according to a supra-national perspective. Conclusions: The new syntaxonomic scheme provides a comprehensive overview of the chasmophytic vegetation of the central part of the Mediterranean Basin. This scheme mostly matches the recently published EuroVegChecklist, but also exhibits important novelties concerning the syntaxonomic position of some alliances (Dianthion rupicolae, Centaureion pentadactyli, Arenarion bertolonii and Caro-Aurinion), and the floristic and chorological relationships among high-rank syntaxa, with new revised sets of diagnostic taxa. This revision might be useful for further small-scale phytosociological studies. Íl4 I © 2018 International Association for Vegetation Science wileyonlinelibrary.com/journal/avsc Appl VegSci. 2018;21:514-532. TERZIet al. KEYWORDS Adriatic Basin, Asplenietaliaglandulosi, Asplenietea trichomanis, Centaureo-Campanuletalia, chasmophytes, classification of vegetation, indicator species analysis, Mediterranean vegetation, Onosmetalia frutescentis, syntaxonomy, Tinguarrenalia siculae 1 | INTRODUCTION Mediterranean cliffs harbour a very specialized flora, comprising many rare and endemic taxa, and are considered a habitat worthy of protection. The Directive 92/43/EEC of the EU Commission lists calcareous and siliceous rocky cliffs with chasmophytic vegetation as habitat types 8,210 and 8,220, respectively. The effective conservation of these habitats could be enhanced by a consistent classification on a supranational scale. The first phy-tosociological synthesis for the Mediterranean chasmophytic vegetation was provided by Meier and Braun-Blanquet (1934), who coined the class 'Asplenietales rupestris' (recte: Asplenietea trichomanis) and four orders within this class. Three of these orders {Androsacetalia multiflorae', 'Potentilletalia caulescentis' and Asplenietalia glandulosi') occur in Europe. Subsequently, due to the regional floristic diversification and richness in local endemics and rare species which characterizes these vegetation types (Davis, 1951), several other orders have been proposed for the chasmophytic vegetation of the Mediterranean Basin. According to the EuroVegChecklist (EVC), a recently proposed syntaxonomic classification system for the vegetation types of Europe (Mucina etal., 2016), the Asplenietea trichomanis include 13 orders. The Asplenietalia glandulosi are restricted to limestone substrates in the thermo-mesomediterranean belt of the western Mediterranean and are replaced by the Centaureo dalmaticae-Campanuletalia pyramidalis in the Adriatic coastal area, by the Moltkietaliapetraeae towards the inland western Balkans, and by the Onosmetalia frutescentis in the southern Adriatic and Ionian seaboards. On siliceous substrates, the Asplenietalia glandulosi are replaced by the Asplenietalia lanceolato-obovati (Mucina &Theurillat, 2015). These orders and their subordinate alliances have been addressed in many phytosociological papers, the most influential being those of Meier and Braun-Blanquet (1934), Horvatic (1934, 1963), Braun-Blanquet, Roussine, and Negre (1952), Rivas Goday, Borja Carbonell, Monasterio Fernandez, Fernandez-Galiano, and Rivas Martfnez (1956), de Bolosand Molinier (1958), Rivas-Martfnez (1960), Quezel (1964), Lakusic (1968), Horvat, Glavac, and Ellenberg (1974), Brullo and Marceno (1979), Trinajstic (1980, 2008), Bianco, Brullo, Pignatti, and Pignatti (1988), Martfnez-Parras and Peinado (1990), Arrigoni and Di Tommaso (1991), Dimopoulos, Sykora, Mucina, and Georgiadis (1997), Rivas-Martfnez, Fernandez-Gonzalez, Loidi, Lousa, and Penas (2001), Rivas-Martfnez etal. (2011), Brullo, Scelsi, and Spampinato (2001), Brullo, Marceno, and Siracusa (2004), Rodwell etal. (2002), Brullo and Spampinato (2003), Di Pietro and Wagensommer (2008), Terzi and D'Amico (2008) and Mucina etal. (2016). However, many aspects of the floristic, synchorological and syntaxonomic relationships among these syntaxa were in most cases based on expert judgements rather than on overall statistical comparison, leading to different and sometimes contradictory interpretations. The Asplenietalia glandulosi range, for instance, was originally extended southwards to North Africa and eastwards to the east Adriatic coast (Meier & Braun-Blanquet, 1934). On the other hand, some authors replaced the Asplenietalia glandulosi with other vicariant orders in Sardinia (Arrigoni & Di Tommaso, 1991), North Africa and south Italy (Daumas, Quezel, & Santa, 1952) and the Adriatic area (Lakusic, 1968; Trinajstic, 1980). Rivas-Martfnez etal. (2001, 2011) and Costa etal. (2012) clarified the syntaxonomy and nomenclature of the chasmophytic vegetation of the Iberian peninsula. Recent studies (Terzi & Di Pietro, 2016; Terzi, Jasprica, & Cakovic, 2017) reviewed the nomenclature of the Asplenietalia glandulosi and its vicariant orders in the central part of the Mediterranean Basin. This area is particularly interesting from a biogeographic viewpoint since cliff plants from both the western and eastern Mediterranean occur. The aim of this paper is to revise the syntaxonomy of the Asplenietalia glandulosi, Centaureo-Campanuletalia and Onosmetalia frutescentis in the central part of the Mediterranean Basin, across a wide area ranging from France to Greece. In more detail, this paper aims to identify: (a) the syntaxonomic and synchorological relationships among the above-mentioned orders and their alliances; and (b) the diagnostic species of the high-rank syntaxa under a supranational perspective. 2 | METHODS 2.1 | Nomenclature The nomenclature of plant taxa follows Euro+Med Plantbase (http:// ww2.bgbm.org/EuroPlusMed/, accessed on July 2017) and The Plant List (http://www.theplantlist.org/ accessed on October 2017) for genera not included in the Euro+Med PlantBase. The Plant list was also used for Bituminaria, Campanula, Dianthus, and Iris. For the Galium lucidum group, the nomenclature follows Conti & Bartolucci (2009). Syntaxonomic nomenclature follows Terzi etal. (2017) and Mucina et al. (2016) for syntaxa not included there. 2.2 | Data set The data set consisted of 1261 phytosociological releves (comprising 959 taxa) of chasmophytic vegetation, already classified within the Asplenietalia glandulosi or in its vicariant orders. The releves were recorded along the Mediterranean coastal and subcoastal areas of southern France, Italy, Malta, Slovenia, Croatia, Bosnia and TERZI etal. FIGURE 1 Map of the study area. The bold type numerals indicate the numbers of releves in the data set for each geographic area. Normal type numerals represent the additional releves summarized in synoptic columns of associations used for the NMDS ordination Herzegovina, Montenegro, Albania and continental Greece (Figure 1, Supporting information Appendix SI). In the data matrix, taxa indicated only at the genus level were omitted as well as bryophytes and lichens that were inconsistently recorded in phytosociological tables. Taxonomically closely related taxa were reported under the same tag if their differentiation among releves in the data set was uncertain. The taxon cover-abundance scores of the original tables were transformed according to the ordinal scale of van der Maarel (1979). Information about the plot size of the releves in the data set, was missing for 96 releves. The average plot size of releves was 58.4 m2. Extremely small (<5 m2) and extremely large (>150 m2) plot sizes were removed from the data set since they could affect the results of statistical analyses (Otýpková & Chytrý, 2006). Nomenclatural type-relevés (Weber, Moravec, &Theurillat, 2000) were always retained. The data set was resampled following the method proposed by De Cáceres, Font, and Oliva (2008; a 'resemblance-based re-sampling' according to De Cáceres etal., 2015). The S0rensen coefficient (related to the Bray-Curtis coefficient; Kent, 2012) was calculated between each pair of releves on the basis of the presence/absence of taxa and, starting from the lowest distance value, up to the arbitrary threshold of 0.3 (see also Westhoff & van der Maarel, 1978), one relevé for each pair was randomly deleted. If a nomenclatural type relevé was involved, it was always retained. The resulting data matrix consisted of 777 releves and 925 taxa. 2.3 I Releves clustering Taxon scores were exponentially transformed to weight the cover-abundance values according to x' = xy (van der Maarel, 1979; Terzi, 2015; Wildi, 2010). Five data matrices were obtained by setting y = 2 (close to the mid-point of the percentage cover ranges of the Braun-Blanquet scale), y = 1 (ordinal scale), y = 0.5 (square root; low weight to cover), y = 0.25 (very low weight to cover) and y = 0 (presence/absence). Each transformed data matrix was subjected to hierarchical clustering using the Flexible Beta method (p = -0.25) in combination with S0rensen coefficient. In all, five dendrograms were obtained using the software PC-ORD, version 6.22 (MjM Software, Gleneden Beach, OR, US). 2.4 I Indicator species analysis (ISA) An ISA (Dufréne & Legendre, 1997) was run for the first 15 partitioning levels of each dendrogram, the first level being the trivial partition with all the releves in only one group. Since this revision focuses on high-rank syntaxa, the analysis was restricted to the first 15 partitions, further divisions dealing with minor variations (only 13 alliances are represented in the data set; Supporting information Appendix SI). In order to obtain a stronger indication, the indicator values (IndVal; Dufréne & Legendre, 1997) were calculated on the basis of the presence/absence of taxa occurring in at least three releves (see Tichý & Chytrý, 2006: 814, eq. 7). For each partitioning level, a taxon was identified as indicator species (IndSp) of a cluster if its IndVal yielded the highest value for that cluster and if it was significant (p < 0.05) in a Monte Carlo Test with 10,000 permutations. The numbers of IndSp along the descending hierarchical typology of a dendrogram are considered as an 'objective criterion for picking the most ecologically meaningful point to prune a dendrogram from cluster analysis' (McCune & Grace, 2002); therefore the five dendrograms were pruned at the partitions yielding the highest number of IndSp. In order to choose the best clustering solution, the cumulative number of IndSp of each dendrogram, from the second partition up to the level at which it had been pruned, was compared with the cumulative number of IndSp counted for the same partitioning levels of the other dendrograms. Many taxa turned out to be IndSp of more than one cluster along the hierarchical descending typology of the dendrogram. In accordance with Dufréne and Legendre (1997), we considered as the best clustering level of an IndSp, the level for which the IndVal first reached its highest value. As a consequence, each IndSp was TERZIet al. Information remaining (%) 100 50 0 FIGURE 2 Cluster analysis of releves [Flexible Beta method (p = -0.25), with S0rensen coefficient, on a square root-transformed distance matrix]. The main clusters of releves are abbreviated as follows: Tsa_4 = Tinguarrenalia siculae: Dianthion rupicolae and Centaureion pentadactyli (Cp); Aga. 2 = Asplenienalia glandulosi. Aga = Centaureo filiformis-Micromerion cordatae; Ag2 = Asplenion glandulosi and Brassicion insularis (Bi); Ofr = Onosmetalia frutescentis/Campanulion versicoloris; CCj_3 = Centaureo-Campanuletalia: CC1 = Asperulion garganicae (IA = Iberido carnosae-Athamantetum siculi); CC2 = Caro multiflori-Aurinion megalocarpae; CC3 = Centaureo dalmaticae-Campanulion (CC) and Centaureo cuspidatae-Portenschlagiellion ramosissimae (CP); Lc = Linarion caprariae; Et = Edraianthion tenuifolii assigned to only one dendrogram cluster (Supporting information Appendix S4). For some species, the IndVal of the first (trivial) partition with all the releves in only one group turned out to be higher than the IndVal calculated for the following partitioning levels. These IndSp were associated to the first level of the dendrogram (Figure 2: cluster It). The syntaxonomic interpretation of the dendrogram was based on the presence in the clusters of the nomenclatural type releves (i.e., 'that element of the syntaxon with which its name is permanently attached'; Weber etal., 2000). Diagnostic taxa of each high-rank syntaxon were deduced from the IndSp associated to the relevant cluster or to its subdivisions. The phytosociological roles given to species in some influential papers on chasmophytic vegetation (Supporting information Appendix S5) supported our subjective Applied Vegetation Science —1- selection of IndSp in order to identify the diagnostic taxa of each syntaxon. 2.5 | Non-metric multidimensional scaling (NMDS) The floristic relationships among associations were visualized by means of NMDS using the S0rensen coefficient. Only the associa-tions/subassociations tables composed of at least five phytosociological releves were considered (Supporting information Appendix S2). In a few cases, more than one phytosociological table was available for the same associations/subassociations and, in these cases, we considered only one of them. For several associations/subassociations we were able to find only a few releves or none at all (in the latter case, these syntaxa were not represented in the cluster analysis). For them, if synoptic tables were available, they were added to the data matrix subjected to NMDS, substituting the Roman numerals constancy values with the central value of the relevant frequency class. In order to evaluate the syntaxonomic relationships of the Dianthion rupicolae and Linarion caprariae with the Asplenietalia lanceolato-obovati, three French associations belonging to the Antirrhinion asarinae - which is the order nomenclatural type - were added. Moreover, we added three synoptic columns representing the original diagnoses of the Phagnalo sordidi-Asplenietum glandulosi and its two subassociations, the Phagnalo-Asplenietum being the nomenclatural type of the Asplenion glandulosi which, in turn, is the type alliance of the Asplenietalia glandulosi. The final data matrix consisted of 87 synoptic columns and 919 taxa (Supporting information Appendix S2). The NMDS ordination was performed by selecting the 'slow and thorough' autopilot mode of PC-ORD, which implies a maximum of 500 iterations, an instability criterion of 10"8, 250 real runs and 250 randomized runs, with six axes as starting point (MjM Software). For each syntaxon represented in the NMDS ordination, the chorological spectrum weighted by taxa frequencies was calculated. Chorotypes were selected on the basis of information provided in Pignatti (1982) and Euro+Med Plantbase (Supporting information Appendix S3). Joint plots with an r2 cut-off of 0.30 were performed to display in the ordination diagram the strengths of the relationships among the ordination scores and the chorological spectra. 2.6 | Multi-response permutation procedure (MRPP) An MRPP (Biondini, Bonham, & Redent, 1985) was used to determine whether the alliances represented in the NMDS were significantly different from each other. Two alliances were excluded from the test: Brassicion insularis represented by only one association (synoptic column) and Edraianthion tenuifolii, to which we referred only two associations. MRPP was applied to the rank transformed distance matrix, with the S0rensen coefficient as dissimilarity measure, as implemented in the software PC-ORD, in order to enhance the correspondence of the results with the NMDS (McCune & Grace, 2002). Applied Vegetation Science 3 | RESULTS 3.1 | Cluster analysis We found five dendrograms that were similar in the overall structure. The main differences relate to the position of the Linarion caprariae, Centaureion pentadactyli and the various associations considered below. These differences are considered in the interpretation of results. The best clustering solution turned out to be that obtained using the square root-transformed data matrix and this will be addressed henceforth. The highest number of IndSp was reached at the 11th level, giving 11 main clusters of releves (Figure 2). On the basis of the position of the type releves, the clusters are considered as representative of the associations and alliances indicated in Table 1. Further insights were obtained by considering further subdivisions of some clusters. The first two partitions of the dendrogram separate the western associations (Figure 2, clusters TS14 and Agj_2) from the eastern ones (clusters Ofr, CCM and Lc+Et). Syntaxa from southwest Italy and Malta are distributed within four main clusters (TSj_4). One of them (Ts4) includes the associations of the Centaureion pentadactyli; the other three clusters represent two new suballiances of the Dianthion rupicolae, namely the Dianthenion rupicolae (clusters TSj and Ts2) and Campanulenion fragilis (Ts3). The associations from Sardinia (cluster Agj) and those from northwest Italy and southern France (Ag2) are grouped in cluster 3a. On the other side of the dendrogram, the associations of the Onosmetalia frutescentis from Greece (cluster Ofr) are well differentiated from the others. The clusters CCM include associations from the southeast of Italy (CCj. 2) and from the west Balkans (CC3). The cluster Lc+Et includes associations sufficiently different from all the others to be classified in other orders. 3.2 | Indicator species analysis Few IndSp were associated with the first partition of the dendrogram (Figure 2, cluster It; Supporting information Appendix S4). Among them, Asplenium ceterach and Sedum dasyphyllum are class character species while the others are considered as ingressive [Parietaria judaica, Ficus carica) or high-frequency companion species. Cluster 2a and its further subdivisions (clusters TSj.j, which represent southwest Italy and Malta, are characterized by many IndSp, with some of them showing high IndVal. Among these taxa, there are some character species of the class (e.g., Umbilicus rupes-tris) and the Asplenietalia glandulosi (e.g., Teucrium flavum). Clusters Agj.2, representing the associations occurring in the northern part of the Asplenietalia glandulosi range, are characterized by many IndSp, among which the character taxa of the alliances Asplenion glandulosi, Brassicion insularis and Centaureo-Micromerion. On the other side of the dendrogram, clusters 3b, 4b and 7a exhibit few IndSp, testifying to a less homogeneous composition. In contrast, the clusters Ofr [Onosmetalia frutescentis), CC1 [Asperulion gar-ganicae), CC2 [Caro-Aurinion) and CC3 [Centaureo-Campanulion and TERZI et al. Centaureo-Portenschlagiellion) turned out to be floristically well differentiated, exhibiting numerous IndSp and high IndVal. Despite the floristic similarities among the alliances of the Adriatic area, there is a marked differentiation between the eastern and western alliances. 3.3 | Non-metric multidimensional scaling and MRPP The NMDS ordination resulted in a three-axis solution (Figure 3), with a final stress of 16.4. The ordination explained 61.8% of the total proportion of variance, axes 1, 2 and 3 accounting for 19.9%, 21.6% and 20.2% of variance, respectively. The western alliances belonging to the Asplenietalia glandulosi were clearly separated from the eastern ones belonging to the Onosmetalia frutescentis and Centaureo-Campanuletalia, with the only exception being the Campanulo-Portenschlagielletum (Figure 3b, n° 13 and 14). The Antirrhinion asarinae is distinguishable on the left side of axis 1 (Figure 3a), as well as the two subassociations of the Campanulo-Moltkietum described for Mount Lovcen, which should be classified in the Edraianthion tenuifolii. Moreover, within the Asplenietalia glandulosi, the separation between the alliances occurring in the northern part of the order [Asplenion glandulosi, Centaureo filiformis-Micromerion corda-tae, Brassicion insularis) and those occurring in the southern part [Centaureion pentadactyli, Dianthion rupicolae) was observed, thus confirming the results of the cluster analysis. The west steno-Mediterranean chorotype is well represented in the Asplenietalia glandulosi (positive correlation with axis 3; r2 = 0.43). The southern associations of the order (i.e., Tinguarrenalia siculae) exhibit higher percentages of steno-Mediterranean taxa. The Campanulion versicoloris is characterized by high percentages of south Balkan and east-steno-Mediterranean taxa (positive correlation with axis 2 of these two chorotypes: r2 = 0.39 and r2 = 0.33, respectively). The other relationships between ordination scores and chorological types show negative correlations of axis 2 with Italian-Balkan (r2 = 0.63), Balkan (r2 = 0.25) and west Balkan (r2 = 0.23) types and negative correlation of axis 1 with European (r2 = 0.46) and Circumboreal (r2 = 0.40) types (Figure 3). The MRPP results revealed that the alliances represented in the NMDS diagram significantly differ in species composition. Moreover, all the pair-wise comparisons between alliances showed significant (p < 0.05) differences except (after Bonferroni correction) comparisons involving alliances represented by three or four synoptic columns only (Supporting information Appendix S7). 4 | SYNTAXONOMIC SCHEME On the basis of the results shown above, the following syntaxonomic scheme is proposed (see also Tables 2 and 3, Figure 4; the order Moltkietalia petraeae is added to the scheme below only for the two new associations): TERZlET al. TABLE 1 Associations included in the main clusters of the dendrogram (Figure 2). Each association was assigned to a cluster on the basis of the position in the dendrogram of its type releve. The associations marked with an asterisk (*) are the nomenclatural types of the alliances reported in the last column Cluster Cluster Ts, Cluster Ts, Cluster Ts, Cluster Ts. Cluster Agj Cluster Ag2 Cluster Ofr Cluster CC, Cluster CC, Cluster CC, Cluster Lc+Et Anthemido cupanianae-Centaureetum busambarensis, Bupleuw dianthifolii-Scabiosetum limonifoliae, Scabiosetum creticae (Scabioso creticae-Centaureetum ucriae nom. illeg.*) and Brass/co rupestris-Centaureetum saccensis Erucastretum virgati, Brass/co villosae-Diplotaxietum crassifoliae and Micromerio microphyllae-Putorietum calabricae and Triadenio aegypticae-Chiliadenetum bocconei Centaureo cinerariae-Campanuletum fragilis and Campanulo fragilis-Portenschlagielletum ramosissimae Diantho rupicolae-Centaureetum aeolicae Subcluster Cp: Arabido collinae-Centaureetum aspromontanae, Centaureo pentadactyli-Dianthetum aspromontani, Centaureo pentadactyli-Dianthetum longicaulis and Centaureo pentadactyli-Dianthetum pentadactyli* Helichryso saxatilis-Cephalarietum mediterraneae and Laserpitio garganici-Asperuletum pumilae" Phagnalo sordidi-Asplenietum glandulosi", Ruto divaricatae-Brassi-cetum insularis", and three associations from central and southern Dalmatia (Croatia): Melico minutae-Pseudofumarietum acaulis, Moltkio petraeae-Campanuletum lepidae and Seselio globiferi-Pseudofumarietum acaulis. The latter two, as revealed by the NMDS, belong to the Centaureo-Campanuletalia Asperulo chloranthae-Daphnetum jasmineae, Asperulo arcadiensis-Hypericetum vesiculosa, Sideritido roeseri-Alkannetum graecae, Inulo parnassicae-Ptilostemetum chamaepeuces, Stachyo candidae-Calietum boryani, Inuletum rotundifoliae and Saxifrago chrysosplenifoliae-Athamantetum macedonicae Campanulo garganicae-Aubrietetum italicae", Pimpinello tragii-Inuletum verbascifoliae, Centaureetum subtilis, Scabiosetum dallaportae and Iberido carnosae-Athamantetum siculi Aurinio megalocarpae-Centaureetum brullae", Campanulo versicoloris-Aurinietum leucadeae and Piptathero-Campanuletum versicolor's Subcluster CC: Aurinio petraeae-Centaureetum lubenicensis, Thalictro velebitici-Campanuletum fenestrellatae, Asplenio lepidi-Moehringietum tommasinii, Saturejo-Euphorbietum wulfenii, Campanulo pyramidalis-Centaureetum kartschianae, Crithmo maritimi-Centaureetum dalmaticae", Seslerio tenuifoliae-Scorzo-neretum austriacae and Centaureetum ragusinae Subcluster CP: Campanulo pyramidalis-Moltkietum petraeae, Inulo verbascifoliae-Centaureetum cuspidatae", Fibigio triauetrae-Ce-rinthetum tristis, Moltkio petraeae-lnuletum verbascifoliae, Moltkio petraeae-Centaureetum voraginicolae nom. inval., Micromerio kerneri-Onosmetum dalmaticae, Teucrio arduinii-Seselietum globiferi and Seslerio robustae-Putorietum calabricae Subcluster Lc: Centaureo aetaliae-Linarietum caprariae, Linario caprariae-Umbilicetum rupestris and Robertio taraxacoidis-Cen-taureetum ilvensis" Subcluster Et: Campanulo pyramidalis-Moltkietum petraeae campanuletosum pyramidalis and C.p.-M.p. scabiosetosum graminifoliae Distribution Sicily, Egadi islands (IT) Sicily (IT) and Malta Calabria and Campania regions (IT) Eolian islands (IT) Aspromonte Massif (IT) Sardinia (IT) Southern France, Corsica (FR), central and southern Dalmatia (HR) Greece Gargano and Murge (IT) Salento (IT) Central and northern Dalmatia (HR), Slovenia and northeast Italy Central and southern Dalmatia (HR) Alliances Dianthion rupicolae Dianthion rupicolae Dianthion rupicolae Dianthion rupicolae Centaureion pentadactyli Centaureo filiformis-Mi-cromerion cordatae Asplenion glandulosi, Brassicion insularis Campanulion versicolor's Asperulion garganicae Caro multiflori-Aurinion megalocarpae Centaureo-Campanulion Centaureo-Portenschlagiellion Tuscan Archipelago (IT) Linarion caprariae Montenegro Edraianthion tenuifolii 520 TERZI et al. to 3 Axis 1 Axis 3 FIGURE 3 NMDS ordination of associations (see Supporting information Appendix S2 for list of associations). Axes 1, 2 and 3 (a, b) account for 19.9%, 21.6% and 20.2% of the variance, respectively. Syntaxa abbreviations: Ag = Asperulion garganicae; CA = Caro multiflori-Aurinion megalocarpae; CC = Centaureo dalmaticae-Campanulion; Cp = Centaureion pentadactyli; CP = Centaureo cuspidatae-Portenschlagiellion ramosissimae; Abbreviation of chorotypes: BIT = Italian-Balkan; BL = Balkan; BLs = south Balkan; BLw = west Balkan; CIR = Circumboreal; EUR = European; MD = steno-Mediterranean; MDe = east steno-Mediterranean; MDw = west steno-Mediterranean Asplenietea trichomanis Diagnostic taxa (D.t): Allosoms pteridioides, Asplenium ceterach, Asplenium ruta-muraria, Asplenium trichomanes, Capparis spinosa aggr., Centranthus ruber subsp. ruber, Euphorbia dendroides, Ephedra foeminea, Ficus carica, Melica minuta, Parietaria judaica, Phagnalon ru-pestre subsp. illyricum, Phagnalon rupestre subsp. graecum, Pimpinella tragium, Polypodium cambricum subsp. cambricum, Putoria calabrica, Sedum dasyphyllum, Teucrium flavum subsp. flavum, Umbilicus horizontal'^, Umbilicus rupestris. • Asplenietalia glandulosi [syn. Arenario bertoloni-Phagnaletalia sordidi] D.t.: Antirrhinum majus, Cosentinia vellea subsp. vellea, Dianthus longicaulis, Dianthus siculus, Lobularia maritima (d), Melica minuta, Phagnalon saxatile, Teucrium flavum subsp. flavum. Other taxa with high IndVal (>20): Geranium purpureum, Juniperus phoe-nicea, Sedum sediforme. Distribution: western Mediterranean Basin. o Asplenienalia glandulosi subord. nov. hoc loco [holotypus: Asplenion glandulosi Braun-Blanquet et Meier in Meier et Braun-Blanquet 1934: 23] D.t.: Asplenium petrarchae (Asplenium glandulosum), Brassica insularis, Chiliadenus glutino-sus, Hormathophylla spinosa, Mercurialis huetii, Phagnalon sor-didum. Distribution: northern part of western Mediterranean Basin, with outposts in the Adriatic area. In the Italian peninsula the boundary between the Asplenienalia glandulosi and the Tinguarrenalia siculae roughly lies in the Lazio region (Central Italy). - Asplenion glandulosi D.t.: Asplenium petrarchae, Erodium foeti-dum, Malva subovata, Melica amethystina. Other taxa with high IndVal (>20): Galium corrudifolium, Lactuca perennis, Thymus vulgaris. Associations: Asplenio-Campanuletum macrorhizae; Diantho brachyanthi-Lavateretum maritimae; Hieracio stelligeri-Alys-setum spinosae; Melico minutae-Pseudofumarietum acaulis; Phagnalo sordidi-Asplenietum glandulosi. - Centaureo filiformis-Micromerion cordatae D.t.: Arenaria bale-arica (d), Arenaria bertolonii (d), Asperula pumila, Bituminaria morisiana, Centaurea filiformis, Cephalaria squamiflora subsp. mediterranea, Helichrysum saxatile, Hypochaeris robertia (d), Lactuca longidentata, Limonium morisianum, Micromeria filiformis subsp. cordata, Seseli praecox, Sesleria insularis (d), Siler montanum subsp. garganicum (d). Other taxa with high IndVal (>20): Allium subhirsutum, Arabis hirsuta, Bellium bellid-ioides, Brachypodium retusum, Clematis cirrhosa, Coronilla Valentina, Galium lucidum, Helianthemum croceum, Quercus ilex, Rosmarinus officinalis, Stachys glutinosa, Teucrium marum. Associations: Helichryso saxatilis-Cephalarietum mediterraneae; Laserpitio garganici-Asperuletum pumilae. - Brassicion insularis D.t.: Brassica insularis, Ruta divaricata Association: Asplenio rutae-murariae-Arenarietum bertolonii. o Tinguarrenalia siculae (Daumas etal. 1952) Galan de Mera in Perez-Latorre, Galan de Mera, Deil et Cabezudo 1996 TERZlET al. TABLE 2 Abridged synoptic table of the order Asplenietaliaglandulosi in the central Mediterranean Columns Number of associations 2 Number of releves 61 Applied Vegetation Science 521 9 358 Campanulenion fragilis Campanula fragilis Seseli polyphyllum Centaurea cineraria Dianthenion rupicolae and Dianthion rupicolae Brassica incana Antirrhinum siculum Dianthus rupicola Glandora rosmarinifolia Convolvulus cneorum Seseli bocconi Iberis semperflorens Odontites bocconei Anthemis cupaniana Brassica rupestris Cymbalaria muralis subsp. pubescens Helichrysum pendulum aggr. (species of Sicily) Matthiola incana subsp. rupestris Asperula rupestris Brassica macrocarpa Pseudoscabiosa limonifolia Centaurea busambarensis Centaurea panormitana subsp. ucriae Centaurea panormitana subsp. umbrosa Erucastrum virgatum Centaureion pentadactyli Silene calabra Allium pentadactyli Centaurea pentadactyli Crepis aspromontana Dianthus brutius Tinguarrenalia siculae Ballota hispanica Hyoseris radiata Hypochaeris laevigata Lomelosia cretica Athamanta sicula Brassica fruticulosa Silene fruticosa Euphorbia bivonae Asplenion glandulosi Erodium foetidum 100 100 50 100 50 50 50 50 100 50 50 11 33 78 67 22 11 67 56 44 33 33 33 33 33 22 22 22 11 11 11 11 44 78 78 67 67 11 67 22 4 50 5 190 6 2 63 100 75 75 50 25 50 25 100 50 25 100 50 60 (Continues) Applied Vegetation Science TERZI etal. TABLE 2 (Continued) Columns 3 4 Number of associations 2 9 4 5 1 2 Number of releves 61 358 50 190 6 63 Melica amethystina 60 Lactuca perennis 40 Malva subovata 40 Thymus vulgaris 40 Brassicion insularis Brassica insularis 100 50 Ruta divaricata 100 Centaureo filiformis-Micromerion cordatae Arenaria balearica 100 Centaurea filiformis 100 Cephalaria squamiflora subsp. mediterranea 100 Helichrysum saxatile 100 Hypochaeris robertia 100 Micromeria filiformis subsp. cordata 100 Seseli praecox 100 Sesleria insularis 100 100 Siler montanum subsp. garganicum 100 Arenaria bertolonii 50 Asperula pumila 50 Bituminaria morisiana 50 Lactuca longidentata 50 Asplenienalia glandulosi Phagnalon sordidum 60 100 50 Hormathophylla spinosa 60 Asplenium petrarchae 50 22 40 Chiliadenus glutinosus 20 Mercurialis huetii 20 Asplenietalia glandulosi Melica minuta 50 78 80 100 100 Teucrium flavum subsp. flavum 100 89 75 60 Dianthus longicaulis 100 11 25 100 Phagnalon saxatile 50 44 75 50 Lobularia maritima 44 75 50 Dianthus siculus 11 25 100 Antirrhinum majus 20 Cosentinia vellea subsp. vellea 11 Asplenietea trichomanis Asplenium ceterach 100 67 75 100 100 100 Sedum dasyphyllum 100 78 50 100 100 100 Ficus carica 100 78 25 40 100 50 Parietaria judaica 50 67 50 40 100 50 Asplenium trichomanes 50 33 25 100 100 100 Polypodium cambricum subsp. cambricum 50 78 50 40 100 50 (Continues) TERZlET al. TABLE 2 (Continued) Columns Number of associations Number of releves Euphorbia dendroides Umbilicus rupestris Capparis spinosa aggr. Hippocrepis emerus subsp. emeroides Centranthus ruber subsp. ruber Phagnalon rupestre subsp. illyricum Umbilicus horizontal's Asplenium ruta-muraria Putoria calabrica Allosorus pteridioides 80 11 11 50 Note. Columns report the percentage frequencies of character and differential taxa in the associations of the alliances: column 1: Campanulenionfragilis; col. 2: Dianthenion rupicolae and Dianthion rupicolae; col. 3: Centaureion pentadactyli; col. 4: Asplenion glandulosi; col. 5: Brass/c/on insularis; col. 6: Centaureo filiformis-Micromerion cordatae (see Supporting information Appendix S6a for entire synoptic table). D.t: Athamanta sicula, Ballota hispanica, Brassica fruticulosa, Euphorbia bivonae, Hypochaeris laevigata, Lomelosia cretica, Seseli bocconi, Silene fruticosa. Other taxa with high IndVal (>20): Hyoseris radiata, Hyparrhenia hirta, Micromeria graeca. Distribution: southern part of western Mediterranean Basin. Centaureion pentadactyli D.t.: Allium pentadactyli, Centaurea pentadactyli, Crepis aspromontana, Dianthus brutius, Silene calabra. Associations: Arabido collinae-Centaureetum aspromontanae; Centaureo pentadactyli-Dianthetum aspromontani; Centaureo pentadactyli-Dianthetum longicaulis; Centaureo pentadactyli-Dianthetum pentadactyli. Dianthion rupicolae D.t.: Anthemis cupaniana, Antirrhinum sic-ulum, Asperula rupestris, Brassica bivoniana, Brassica drepan-ensis, Brassica incana, Brassica macrocarpa, Brassica rupestris, Centaurea busambarensis, Centaurea panormitana subsp. ucriae, Centaurea panormitana subsp. umbrosa, Convolvulus cneo-rum, Cymbalaria muralis subsp. pubescens, Dianthus rupicola, Erucastrum virgatum, Genista gasparrinii, Glandora rosmarin-ifolia, Helichrysum pendulum aggr. (species of Sicily), Iberis semperflorens, Matthiola incana subsp. rupestris, Micromeria microphylla (d), Odontites bocconei, Pseudoscabiosa limonifolia, Seseli bocconi, Silene fruticosa. Other taxa with high IndVal (>20): Centaurea tauromenitana, Dianthus arrostii, Erica multi-flora, Galium pallidum. Dianthenion rupicolae suball. nov. hoc loco [holotypus: Scabioso creticae-Centaureetum ucriae Brullo et Marcend 1979: 139] D.t.: Anthemis cupaniana, Asperula rupestris, Brassica rupestris, Cymbalaria muralis subsp. pubescens, Genista gasparrinii, Iberis semperflorens, Matthiola incana subsp. rupestris, Odontites bocconei, Pseudoscabiosa limonifolia, Seseli bocconi, Silene fruticosa. Associations: Anthemido cupanianae-Centaureetum busambarensis; Brassico rupestris-Centaureetum saccensis; Brassico villosae-Diplotaxietum crassifoliae; Bupleuro dianthifolii-Scabi-osetum limonifoliae; Diantho rupicolae-Centaureetum aeolicae; Erucastretum virgati; Micromerio microphyllae-Putorietum cal-abricae; Scabiosetum creticae; Triadenio aegypticae-Chiliadene-tum bocconei; -- Campanulenion fragilis suball. nov. hoc loco [holotypus: Centaureo cinerariae-Campanuletum fragilis Brullo et Marcend 1979: 138] D.t.: Campanula fragilis, Centaurea cineraria, Seseli polyphyllum. Other taxa with high IndVal (>20): Primula palinuri, Athamanta ramosissima. Associations: Centaureo cinerariae-Campanuletum fragilis; Campanulo fragilis-Portenschlagielletum ramosissimae (uncertain syntaxonomic position). • Centaureo dalmaticae-Campanuletalia pyramidalis D.t: Allium am-peloprasum (d), Aurinia leucadea, Aurinia sinuata, Campanula pyramidalis, Convolvulus cneorum, Cytisus spinescens (d), Dianthus tarentinus, Frangula rupestris (d), Inula verbascifolia, Iris illyrica, Leontodon apulus, Picris hispidissima, Onosma echioides subsp. an-gustifolia (d), Sedum hispanicum (d), Seseli globiferum, Sesleria jun-cifolia, Sonchus asper subsp. glaucescens (d). Other taxa with high IndVal (>20): Rhamnussaxatilis subsp. infectoria, Satureja montana. Distribution: Adriatic coasts. - Centaureo cuspidatae-Portenschlagiellion ramosissimae D.t.: Alyssoides utriculata, Asperula scutellaris, Athamanta ramosissima, Campanula portenschlagiana, Centaurea cuspidata, Galium firmum, Iris pseudopallida, Moltkia petraea, Resetnikia triquetra, Seseli tomentosum, Tanacetum cinerariifolium, Teucrium arduinii. 524 Applied Vegetation Science - TABLE 3 Abridged synoptic table of the orders Onosmetaliafrutescentis and Centaureo-Campanuletalia in the central Mediterranean TERZI et al. Columns Number of associations Number of releves Campanulion versicoloris and Onosmetalia frutescentis Campanula versicolor 100 Teucrium flavum subsp. hellenicum 100 Aurinia saxatilis subsp. orientalis 88 Onosma frutescens 88 Bubon macedonicum 75 Centaurea raphanina subsp. mixta 75 Centranthus ruber subsp. sibthorpii 75 Ephedra foeminea 75 Hellenocarum multiflorum 75 Inula pamassica 75 Phagnalon rupestre subsp. graecum 75 Silene congesta 75 Silene gigantea 75 Asperula lutea 63 Campanula rupestris 63 Ptilostemon chamaepeuce 63 Scrophularia heterophylla subsp. heterophylla 63 Aubrieta deltoidea 50 Odontites linkii 50 Asperula arcadiensis 38 Ballota acetabulosa 38 Cephalaria ambrosioides 38 Umbilicus chloranthus 38 Pterocephalus perennis 25 Saxifraga rotundifolia subsp. chrysosplenifolia 25 Asperula chlorantha 13 Campanula anchusiflora 13 Centaureo dalmaticae-Campanulion Euphorbia fragifera Sonchus asper subsp. glaucescens Aurinia petraea Campanula fenestrellata subsp. istriaca Clinopodium thymifolium Campanula fenestrellata subsp. fenestrellata Centaurea kartschiana subsp. dalmatica Centaurea kartschiana subsp. kartschiana Centaurea kartschiana subsp. lubenicensis Moehringia tommasinii Centaurea ragusina Centaureo cuspidatae-Portenschlagiellion ramosissimae Moltkia petraea Alyssoides utriculata 2 9 76 11 11 67 56 22 22 22 11 11 11 11 11 11 4 81 84 75 11 56 100 11 11 11 11 89 78 (Continues) TERZlET al. TABLE 3 (Continued) Columns Number of associations Number of releves Athamanta ramosissima Tanacetum cinerariifolium Seseli tomentosum Campanula portenschlagiana Centaurea cuspidata Galium firmum Iris pseudopallida Asperula scutellaris Resetnikia triquetra Teucrium arduinii Asperulion garganicae Asperula garganica Lomelosia crenata subsp. dallaportae Pimpinella tragium Campanula garganica Centaurea subtilis Doronicum columnae Aubrieta columnae Cam multiflori-Aurinion megalocarpae Scrophularia lucida Aurinia saxatilis subsp. megalocarpa Satureja cuneifolia Centaurea brulla Leontodon intermedius Dianthus japigicus Centaurea leucadea Centaurea japygica Centaurea nobilis Centaurea tenacissima Centaureo dalmaticae-Campanuletalia pyramidalis Satureja montana Sesleria juncifolia Inula verbascifolia Sedum hispanicum Aurinia sinuata Aurinia leucadea Campanula pyramidalis Rhamnus saxatilis subsp. infectoria Leontodon apulus Dianthus tarentinus Picris hispidissima Allium ampeloprasum Iris illyrica 1 8 84 13 9 76 13 56 67 33 33 11 100 33 56 22 78 78 67 33 33 33 33 22 22 11 67 33 100 56 44 11 100 78 33 67 4 81 100 100 100 75 75 75 25 25 100 50 100 50 25 100 75 75 84 25 75 75 50 50 25 25 25 25 25 25 75 25 50 25 75 75 75 (Continues) TERZI et al. TABLE 3 (Continued) Columns 1 2 3 4 5 Number of associations 8 9 6 4 4 Number of releves 84 76 ? 81 84 I Onosma echioides subsp. angustifolia 25 50 Frangula rupestris 13 44 22 Seseli globiferum 11 11 Cytisus spinescens 13 75 Asplenietea trichomanis Asplenium ceterach 75 56 100 75 75 Parietaria judaica 13 100 78 50 100 Ficuscarica 38 67 44 75 100 Asplenium trichomanes 75 44 89 50 25 Teucrium flavum subsp. flavum 25 67 11 75 75 Sedum dasyphyllum 25 22 67 50 75 Hippocrepis emerus subsp. emeroides 50 78 33 25 50 Capparis spinosa aggr. 25 11 22 75 75 Athamanta sicula 13 50 75 Umbilicus horizontalis 25 100 Phagnalon rupestre subsp. illyricum 22 50 50 Melicaminuta 13 25 50 Euphorbia dendroides 13 11 11 50 Asplenium ruta-muraria 33 22 Centranthus ruber subsp. ruber 25 25 Putoria calabrica 38 11 Polypodium cambricum subsp. cambricum 11 11 25 Umbilicus rupestris 25 Note. Columns report the percentage frequencies of character and differential taxa in the associations of the alliances: column 1: Campanulionversicolo-ris and Onosmetalia frutescentis; col. 2: Centaureo dalmaticae-Campanulion; col. 3: Centaureo cuspidatae-Portenschlagiellion ramosissimae; col. 4: Asperulion garganicae; col. 5: Cam multiflori-Aurinion megalocarpae (see Supporting information Appendix S6a for entire synoptic table). The number of releves of the Centaureo cuspidatae-Portenschlagiellion is missing because this information was not provided with the original diagnosis of some associations of this alliance. Associations: Campanulo pyramidalis-Moltkietum petraeae; Fibigio triquetrae-Cerinthetum tristis; Inulo verbascifoliae-Cen-taureetum cuspidatae; Micromerio kerneri-Onosmetum dal-maticae; Moltkio petraeae-lnuletum verbascifoliae; Moltkio petreae-Campanuletum lepidae; Moltkio petraeae-Centaureetum voraginicolae nom. inval.; Portenschlagiello ramosissimae-Cam-panuletum portenschlagianae; Seslerio robustae-Putorietum ca-labricae; Teucrio arduinii-Seselietum globiferi. Centaureo dalmaticae-Campanulion D.t: Aurinia petraea, Campanula fenestrellata subsp. fenestrellata, Campanula fenestrellata subsp. istriaca, Centaurea kartschiana subsp. dal-matica, Centaurea kartschiana subsp. kartschiana, Centaurea kartschiana subsp. lubenicensis, Centaurea ragusina, Clinopodium thymifolium (d), Euphorbia fragifera (d), Moehringia tommasinii. Other taxa with high IndVal (>20): Crithmum maritimum. Associations: Asplenio lepidi-Moehringietum tommasinii; Aurinio petreae-Centaureetum lubenicensis; Campanulo pyramidalis-Centaureetum kartschianae; Centaureetum ra-gusinae; Crithmo maritimi-Centaureetum dalmaticae; Saturejo-Euphorbietum wulfenii; Seselio globiferi-Pseudofumarietum acaulis; Seslerio tenuifoliae-Scorzoneretum austriacae; Thalictro velebitici-Campanuletum fenestrellatae. Asperulion garganicae D.t.: Asperula garganica, Aubrieta columnae, Campanula garganica subsp. garganica, Centaurea subtilis, Doronicum columnae (d), Lomelosia crenata subsp. dallaportae, Pimpinella tragium. Other taxa with high IndVal (>20): Festuca circummediterranea. Associations: Campanulo garganicae-Aubrietetum italicae; Centaureetum subtilis; Pimpinello tragii-lnuletum verbascifoliae; Scabiosetum dallaportae. Caro multiflori-Aurinion megalocarpae D.t.: Aurinia saxatilis subsp. megalocarpa, Campanula versicolor, Centaurea brulla, Centaurea japygica, Centaurea leucadea, Centaurea nobi-lis, Centaurea tenacissima, Dianthus japigicus, Hellenocarum TERZIet al. FIGURE 4 Distribution map of the Asplenienalia glandulosi, Tinguarrenalia siculae, Centaureo-Campanuletalia and Onosmetalia frutescentis in the central Mediterranean muitifiorum, Leontodon intermedius, Satureja cuneifolia (d), Scrophularia lucida. Other taxa with high IndVal (>20): Prasium majus. Associations: Aurinio megalocarpae-Centaureetum brullae; Campanulo versicoloris-Aurinietum leucadeae; Iberido carno-sae-Athamantetum siculi; Piptathero holciformis-Campanuletum versicoloris. • Onosmetalia frutescentis D.t: Asperula arcadiensis, Asperula chlo-rantha, Asperula lutea, Aubrieta deltoidea, Aurinia saxatilis subsp. orientalis, Ballota acetabulosa, Bubon macedonicum, Campanula an-chusiflora, Campanula rupestris, Campanula versicolor, Centaurea ra-phanina subsp. mixta, Centranthus ruber subsp. sibthorpii, Cephalaria ambrosioides, Ephedra foeminea, Hellenocarum muitifiorum, Inula parnassica, Odontites linkii, Onosma frutescens, Phagnalon rupestre subsp. graecum, Pterocephalus perennis, Ptilostemon chamaepeuce, Saxifraga rotundifolia subsp. chrysosplenifolia, Scrophularia hetero-phylla subsp. heterophylla, Silene congesta, Silenegigantea, Teucrium flavum subsp. hellenicum, Umbilicus chloranthus. Other taxa with high IndVal (>20): Arabis alpina subsp. caucasica, Festuca jeanpertii, Fraxinus ornus, Leontodon graecus, Micromeria Juliana, Phlomis fruti-cosa, Ouercus coccifera. Distribution: southern Balkan peninsula. - Campanulion versicoloris Diagnostic taxa: see order. Associations: Asperulo arcadiensis-Hypericetum vesiculosa Asperulo chloranthae-Daphnetum jasmineae; Asperulo chloranthae-Moltki-etum petraeae; Inuletum rotundifoliae; lnulo parnassicae-Ptiloste-metum chamaepeuces; Saxifrago chrysosplenifoliae-Athamantetum macedonicae; Sideritido raeseri-Alkannetum graecae; Stachyo candi-dae-Galietum boryani. • Moltkietalia petraeae - Edraianthion tenuifolii Campanulo austroadriaticae-Moltkietum petraeae (Tomic-Stankovic ex Terzi et al. 2017 nom. corr. hoc loco) comb. nov. (= Campanulo pyramidalis-Moltkietum petraeae Horvatic ex Trinajstic 1964 campanuletosum pyramidalis Tomic-Stankovic ex Terzi etal. 2017: 375; Campanula pyramidalis has to be replaced by Campanula austroadriatica D. Lakusic & Kovacic [see Jankovic etal. 2016]), holotypus: rel. 11, table II, in Tomic-Stankovic (1970). Saxifrago crustatae-Moltkietum petraeae (Tomic-Stankovic ex Terzi etal. 2017) comb. nov. (= Campanulo pyramidalis-Moltkietum petraeae Horvatic ex Trinajstic 1964 scabiosetosum gram-inifoliae Tomic-Stankovic ex Terzi et al. 2017: 375), holotypus: rel. 6, table II, in Tomic-Stankovic (1970) 5 I DISCUSSION The EVC has the advantage of being based on a supranational perspective and, taking into consideration all European vegetation types, provides a general framework for the European area. For these reasons, we adopt the system of three orders proposed in the EVC, Asplenietalia glandulosi, Centaureo-Campanuletalia and Onosmetalia frutescentis. Two other orders, Asplenietalia lanceolato-obovati and Moltkietalia petraeae, are dealt with briefly in the discussion below just in order to highlight their floristic relationships with the Asplenietalia glandulosi and Centaureo-Campanuletalia, respectively. TERZI etal. 5.1 I Asplenietalia glandulosi and Asplenietalia lanceolato-obovati In the central Mediterranean, the Asplenietalia glandulosi is represented by five alliances: Centaureo filiformis-Micromerion cordatae, Asplenion glandulosi, Brassicion insularis, Centaureion pentadactyli and Dianthion rupicolae. According to the EVC, the Dianthion rupicolae (including the Centaureion pentadactyli) should be classified in the Asplenietalia lanceolato-obovati together with the Antirrhinion asarinae (the order typus), Cheilanthion hispanicae of the Iberian peninsula and the Linarion caprariae from the Tuscan Archipelago (IT). The Asplenietalia lanceolato-obovati derives from the change of rank of a suborder of the Androsacetalia vandellii describing the low-altitude Mediterranean vegetation of the siliceous cliffs (Loisel, 1970). However, the nomenclatural type of the Dianthion rupicolae, i.e., the Scabioso creticae-Centaureetum ucriae, and many other, but not all, associations of this alliance were recorded on calcareous bedrock (Brullo & Marceno, 1979; Brullo et al., 2004). Moreover, the inclusion of the Dianthion rupicolae and Centaureion pentadactyli within the Asplenietalia lanceolato-obovati is not supported by a solid floristic component. In fact, this order is characterized by five taxa, Allosorus pteridioides, Asplenium obovatum subsp. billotii, Asplenium obovatum subsp. obovatum, Bufonia macropetala and Phagnalon saxatile (Loisel, 1970; Mucina & Theurillat, 2015). Three of them turned out to be IndSp in our analysis. Allosorus pteridioides and Asplenium obovatum subsp. obovatum are IndSp for clusters 5b (Figure 2: Asplenion glandulosi) and 10b (Linarion caprariae), respectively, but with a very low IndVal (<6; Supporting information Appendix S4). Phagnalon saxatile, which is IndSp of cluster 2a (Asplenietalia glandulosi), is to be considered as a differential species of the Asplenietalia lanceolato-obovati, since it occurs in other orders and classes (e.g., Phagnalo saxatilis-Cheilan-thion maderensis, Asplenietalia glandulosi, Phagnalo saxatilis-Ru-micetea indurati). The NMDS diagram (Figure 3) showed that the Centaureion pentadactyli and the Dianthion rupicolae are clearly separated from the Antirrhinion asarinae (the nomenclatural type of the Asplenietalia lanceolato-obovati), which, for its part, occupies an isolated left-most axis 1 position. For these reasons, the Centaureion pentadactyli and the Dianthion rupicolae are here classified in the Asplenietalia glandulosi. The distribution range of the Centaureion pentadactyli is restricted to the eastern part of southern Calabria (Italy) and is even completely included within the distributional range of the Dianthion rupicolae. However, there are marked biocli-matic differences along the coasts of the two sides of the Calabrian region (Brullo etal., 2001) and the character species of these two alliances turned out to be mutually exclusive (Supporting information Appendix S6). For these reasons, they are here considered as two autonomous syntaxa. On the other hand, the Linarion caprariae is restricted to siliceous cliffs of the Tuscan archipelago (Foggi etal., 2006) and it lacks almost all the diagnostic taxa of the Asplenietalia glandulosi. Hence, we provisionally confirm the classification of this alliance in the Asplenietalia lanceolato-obovati. However, this order needs to be subjected to a thorough revision in order to confirm its autonomy as a distinct order (see also Perez-Carro, Dfaz, Fernandez, & Salvo, 1989) and clarify its floristic relationships with the other chasmophytic syntaxa. Such a revision is beyond the scope of this paper. The Asplenietalia glandulosi is centred in the western Mediterranean. Most of the character taxa of the order, as indicated by Meier and Braun-Blanquet (1934), Braun-Blanquet etal. (1952) and Rivas-Martfnez etal. (2011: 216), have a distribution range west of the Italian peninsula (e.g., Chaenorhinum origanifolium subsp. crassifolium, Chiliadenus glutinosus, Hieracium arragonense, Hormathophylla spinosa, Mercurialis huetii). Other character taxa (e.g., Asplenium petrarchae, Phagnalon sordidum) exhibit a distribution area which includes Italy, but these were rarely or not recorded at all in the releves of the Dianthion rupicolae and Centaureion pentadactyli. The remaining character species, as originally indicated by the aforementioned authors, are particularly abundant in central and southern Italy (Teucrium flavum, Melica minuta and Dianthus longicaulis) or act as differential species for other vegetation types (Phagnalon saxatile, Phagnalon rupestre). The results of both cluster analysis and ISA clearly show that the Dianthion rupicolae and the Centaureion pentadactyli are floris-tically distinguishable from the other alliances of the Asplenietalia glandulosi, due to their high number of endemic/subendemic and steno-Mediterranean taxa. Therefore, these results support a syntaxonomic separation of the cliff vegetation of central and southwest Italy from that of southern France, Corsica, Sardinia and northwest Italy. For this reason, two suborders of the Asplenietalia glandulosi have been considered here: Asplenienalia glandulosi and Tinguarrenalia siculae. According to Daumas etal. (1952), in central and southern Italy, North Africa and southern Spain, the Asplenietalia glandulosi is substituted by the Tinguarretalia siculae. Some of the character species of the Tinguarretalia siculae and of the sole alliance included in its original diagnosis (Rupicapnion africanae Daumas et al. 1952) occur in southern Italy. These species are: Athamanta sicula, Dianthus sylves-tris subsp. siculus, Hypochaeris laevigata, Euphorbia bivonae, Hyoseris radiata, Polygala rupestris (doubtfully), Senecio squalidus subsp. rup-estris, Calendula suffruticosa, Malva subovata subsp. rupestris and Parietaria mauritanica. Athamanta sicula [= Tinguarra sicula], in particular, is well represented and often dominant on calcareous cliffs of central and southern Italy (Pignatti, 1982). Other authors reduced the Tinguarretalia siculae to the rank of suborder of the Asplenietalia glandulosi (Perez-Latorre etal., 1996). Although knowledge of the chasmophytic vegetation of North Africa is fragmented and any evaluation of the coenological relationships between Italy and North Africa must remain open to further refinement, the Dianthion rupicolae and Centaureion pentadactyli are classified in the Tinguarrenalia siculae. The Dianthion rupicolae is composed of two suballiances: Dianthenion rupicolae and Campanulenion fragilis (Table 2, Figure 4, Supporting information Appendix S6a). The Campanulo-Portenschlagielletum is provisionally classified in the Campanulenion TERZIet al. fragilis. In NMDS and in some of our other dendrograms, which we do not include here, this association turned out to segregate together with the Centaureo-Campanuletalia, so its syntaxonomic position should still be considered uncertain. The Asplenienalia glandulosi is centred in the south of France, where the nomenclatural type [Asplenion glandulosi), and its type association [Phagnalo sordidi-Asplenietum glandulosi), were originally recorded. It extends westwards into the Iberian peninsula and eastwards into central Italy and Sardinia (Figure 4). In Sardinia, the Centaureo-Micromerion develops over a wide altitudinal range, from about sea level to over 1,300 m. This has led to several species of the submontane and montane belts occurring in this alliance. Also included among the IndSp of the alliance are Arenaria bertolonii and Sesleria insularis, which were considered as the most diagnostic species of the Corsician alliance Arenarion bertolonii (Mucina & Theurillat, 2015). This latter alliance was classified in the Potentilletalia caulescen-tis (Gamisans, 1991) or in the Arenario-Phagnaletalia (Rodwell etal., 2002), and only recently moved to the Asplenietalia glandulosi (Mucina & Theurillat, 2015). We were not able to find the original diagnosis of the type association of the alliance, Asplenio rutae-murariae-Are-narietum bertolonii (Gamisans, 1975). However, Gamisans (1978: 37) indicated two releves (although there is a possibility that these were the same releves published twice) as lectotypes of this association. One of these releves (releve 2, p. 466, in Gamisans, 1976) - the only one that we were able to check - was recorded at 1,920 m a.s.l. The other releves assigned to this association by Gamisans (1976), not included in our data set, showed weak floristic similarities with the Asplenietalia glandulosi. Given the altitudinal range of the Arenarion bertolonii and following the reasoning provided by Gamisans (1976), we consider this alliance not to be included in the bioclimatic, ecological and floristic ranges of the Asplenietalia glandulosi. The dendrogram cluster representing the Asplenienalia glandulosi also contains the releves of the Melico minutae-Pseudofumarietum acaulis from Croatia. This association was originally classified within the Asplenietalia glandulosi because of the lack of the character taxa of the Centaureo-Campanuletalia and the presence of Melica minuta (Trinajstic, 1980). Subsequently, Trinajstic (2008) moved this association to the Centaureo-Campanuletalia on the basis of geographical considerations, but he did not give floristic arguments. Based on our results, this association is here provisionally classified in the Asplenietalia glandulosi. 5.2 | Centaureo-Campanuletalia and Moltkietalia petraeae The floristic autonomy of the chasmophytic vegetation of the northeast Adriatic region was established by Horvatic (1934), who described the new endemic coastal alliance Centaureo-Campanulion, classifying it in the Asplenietalia glandulosi. Subsequently, Lakusic (1968) described a second alliance for the southeastern Adriatic, the Edraianthion tenuifolii, in which he included both the coastal and inland montane chasmophytic vegetation. He classified the two alliances in the new order Moltkietalia Applied Vegetation Science —1- petraeae. Trinajstic (1980) developed this concept and described the new order Centaureo-Campanuletalia for the coastal cliff vegetation of the Adriatic area in which the Centaureo-Campanulion and Centaureo-Portenschlagiellion, the latter replacing the Edraianthion in the coastal area, were included (see also Terzi & Di Pietro, 2016). The EVC followed the proposal of Trinajstic (1980) in considering a coastal order, Centaureo-Campanuletalia, and an inland order, Moltkietalia petraeae, for the montane and sub-alpine belts. The proposal of Lakusic (1968) to group the coastal and the inland vegetation within a single alliance and order, Edraianthion tenuifolii and Moltkietalia petraeae, respectively, was presumably based on the distribution areas of some sub-Mediterranean taxa that extend inland from the coast. For instance, the two subassoci-ations of the Campanulo pyramidalis-Moltkietum petraeae, described for Mount Lovcen, Montenegro (Terzi et al., 2017; Tomic-Stankovic, 1970), harbour several sub-Mediterranean species. Nonetheless, they belong to the Edraianthion tenuifolii, due to the occurrence of diagnostic taxa, such as Potentilla speciosa, Saxifraga crustata or Daphne alpina, which are typical of cool conditions. Based on our results, these two subassociations represent two autonomous units, separated from the typical Campanulo-Moltkietum, whose locus classicus is in the more xerothermic conditions of the Mediterranean context of the Korcula Island (Trinajstic, 1964). Therefore, they are here raised to the rank of association with the names Saxifrago crustatae-Moltkietum petraeae and Campanulo aus-troadriaticae-Moltkietum petraeae. The Balkan alliances of the Centaureo-Campanuletalia (Figure 2, cluster CC3) turned out to be differentiated from the southern Italian alliances (clusters CCj_2). The occurrence of few order character taxa on the Italian side was highlighted as early as the first work on the Asperulion garganicae (Bianco et al., 1988), where the main character/differential taxa of the Centaureo-Campanuletalia were indicated in Inula verbascifolia, Aurinia sinuata, Sesleria junci-folia and Phagnalon rupestre subsp. illyricum. Other local character taxa, such as Dianthus tarentinus, Onosma echioides subsp. angusti-folia, Cytisus spinescens and Leontodon apulus, were subsequently suggested in order to distinguish the Italian range of the order (Bianco etal., 1988; Di Pietro & Wagensommer, 2008; Terzi & DAmico, 2008). The syntaxonomic position of the Caro-Aurinion has long been debated in the scientific literature and represents one of the most complicated points of this revision. The results of our revision support the classification of this alliance in the Centaureo-Campanuletalia, as already proposed in the Italian Prodromus of Vegetation (Biondi et al., 2014). However, due to some important biogeographic considerations, the Caro-Aurinion lies at the crossroads of three orders. Its syntaxonomic relationships with these orders, and especially with the Onosmetaliafrutescentis, are discussed below. 5.3 | Onosmetalia frutescentis This order was described by Quezel (1964) for the xerothermic chasmophytic vegetation of the high mountains of the Peloponnese, Applied Vegetation Science Greece. Its distribution area was subsequently extended to other parts of Greece, Turkey, Albania, Italy and northward, even up as far as Slovenia (Bianco etal., 1988; Dring etal., 2002; Silc & Carni, 2012). The Onosmetalia frutescentis is not genuinely a central Mediterranean order and it was included in this revision chiefly for comparison with the rest of the syntaxa considered. According to the results of this study, the order represents an autonomous and well differentiated syntaxonomic unit and has to be restricted to the southern Balkans. The order and its sole alliance, Campanulion ver-sicoloris, are characterized by a high number of taxa, >20, which are mostly southern Balkan taxa (Supporting information Appendices S4 and S6b). The chasmophytic vegetation of the Salento peninsula (southeast Italy) was originally classified in the Campanulion versicoloris and Onosmetalia frutescentis (Bianco et al., 1988) and later grouped in a southeast Italian endemic alliance, Caro-Aurinion. This alliance was included in the Onosmetalia frutescentis in the EVC, whereas it has also been classified in the Asplenietalia glandulosi (Terzi & DAmico, 2008) or in the Centaureo-Campanuletalia (Biondi et al., 2014). Di Pietro and Wagensommer (2008) hypothesized an Italian endemic order for this area. The similarities between the Caro-Aurinion and the Campanulion versicoloris are mainly due to three eastern species: Scrophularia lucida, Hellenocarum multiflorum and Campanula versicolor (Bianco etal., 1988). In a revision of the rock cliff vegetation of Greece, Dimopoulos etal. (1997) considered Campanula versicolor as a character species of the Campanulion versicoloris, Hellenocarum multiflorum as a character species of the Asplenietea trichomanis, whereas they did not assign any diagnostic role for Scrophularia lucida. The biogeographic similarities between the Salento peninsula and the southwest Balkans involve some other species typical of other habitats (e.g., Di Pietro & Misano, 2010; Francini-Corti, 1966; Musacchio, Pellegrino, Cafasso, Widmer, & Cozzolino, 2006). As already pointed out in the pioneering work of Trotter (1912), some of the southeastern taxa in the Salento peninsula can be considered as tertiary relict taxa, their occurrence being due to geological vicissitudes which occurred during the Messinian age and earlier. During the more recent glacial-interglacial oscillations, if migrations along land bridges between the Italian peninsula and the Balkans occurred, they took place more in the northern and central part of the Adriatic Basin than in either the southern part or across the Strait of Otranto. The Adriatic bathymetry is characterized by shallow sea floors in the central and northern Adriatic Basin (with a Mid-Adriatic pit of 270 m in depth), whereas the maximum depths are reached in the southern part, at nearly 1200 m occurring along the Bari (IT)-Bar (ME) direction and 800 m along the Strait of Otranto. As a consequence, and long-distance dispersal excepted, the species/gene flow between the two opposite sides of the southern Adriatic Sea might have been interrupted for approximately the last five million years, or it would have had to follow an indirect land migration route. Results of this revision clearly showed the floristic autonomy of the Caro-Aurinion, which is characterized by numerous endemic TERZI etal. or sub-endemic taxa, such as Centaurea brulla, Dianthus japigicus, Centaurea nobilis, Centaurea tenacissima, Centaurea leucadea and Aurinia saxatilis subsp. megalocarpa. Although the distribution area of Aurinia saxatilis subsp. megalocarpa includes both Greece and the south of Italy, in our data set, it occurred only on the Italian side, being replaced by Aurinia saxatilis subsp. orientalis in Greece. Similarly, Scrophularia lucida emerged as a good diagnostic species for the Caro-Aurinion. Campanula versicolor and Hellenocarum multiflorum are well represented in the southern part of the Caro-Aurinion range, together with Aurinia leucadea, principally a south Dalmatian taxon of the Centaureo-Campanuletalia. These taxa lose importance in the northern part of the alliance distribution range and give way to Aurinia saxatilis subsp. megalocarpa and Athamanta sicula, especially in the Iberido carnosae-Athamantetum siculi, which is intermediate between Gargano and Salento vegetation types. Therefore, the Caro-Aurinion comes at the crossroads of the three main orders mentioned so far. Our data set does not include releves from southern Albania and western Greece and the geographic distance between releves from Salento and those from the Peloponnese could be responsible for the floristic differentiation in the dendrogram between the Caro-Aurinion and the Campanulion versicoloris. In fact, a well recognized problem dealing with chasmophytic vegetation concerns the ingression of species from the surroundings (Davis, 1951; Heywood, 1954), leading to a geographic aggregation of releves on the basis of taxa with different ecological requirements. Therefore, further in-depth studies on the chasmophytic vegetation of the southwestern Balkans are strongly recommended in order to resolve the syncho-rology of the Onosmetalia frutescentis at its western boundary. 6 | CONCLUSIONS The syntaxonomic scheme provided in this revision for the chasmophytic vegetation of the central part of the Mediterranean exhibits some important differences with respect to the EVC concerning the alliances Dianthion rupicolae, Centaureion pentadactyli, Arenarion bertolonii and Caro-Aurinion. From a synchorological viewpoint this revision highlighted a north-south floristic differentiation within the Asplenietalia glandulosi and defined the distribution range of the Centaureo-Campanuletalia and Onosmetalia frutescentis more precisely. Furthermore, this revision highlighted some critical interpretative points that might be resolved when fresh data from phyto-sociologically less studied areas become available. Knowledge of the cliff vegetation of North Africa is still insufficient. The same is the case for the order Onosmetalia frutescentis, whose distribution range turns out to be restricted to the southern Balkans, however some doubts remain as regards its western boundaries. Finally, although the Asplenietalia obovato-lanceolati was only marginally treated in this work, it appears that the floristic relationships between this order and the neighbouring syntaxonomic units are still unclear. TERZI et al. ACKNOWLEDGEMENTS We would like to thank J.C. Costa, F.S. DAmico, M. De Cáceres, B. Foggi and G. Spampinato for providing some information that were useful in interpreting the results of this revision, and F. Jansen, Co-ordinating Editor of the journal, and four reviewers for their valuable suggestions. Thanks are also extended to S. Latham and J. McManus for improving the English. MT and NJ conceived and planned the research and contributed data; MT did the analyses and led the writing; all the authors provided substantial input for the interpretation of results and critically revised the manuscript. ORCID Massimo Terzi© http://orcid.org/0000-0001-8801-6733 REFERENCES Arrigoni, P. V., & Di Tommaso, P. L. (1991). La vegetazione delle montagne calcaree della Sardegna centro-orientale. Bollettino delta Societa Sarda diScienze Natural!, 28, 201-310. Bianco, P., Brullo, S., Pignatti, E., & Pignatti, S. (1988). La vegetazione delle rupi calcaree della Puglia. Braun-Blanquetia, 2, 133-151. Biondi, E., Blasi, C, Allegrezza, M., Anzellotti, I., Azzella, M. M., Carli, E.....Zivkovic, L. (2014). Plant communities of Italy: The vegetation prodrome. Plant Biosystems, 148, 728-814. https://doi.org/10.1080/ 11263504.2014.948527 Biondini, M. E., Bonham, C. D., & Redent, E. F. (1985). Secondary suc-cessional patterns in a sagebrush (Artemisia tridentata) community as they relate to soil disturbance and soil biological activity. Vegetatio, 60, 25-36. https://doi.org/10.1007/BF00053909 Braun-Blanquet, J., Roussine, N., & Negre, R. (1952). Les groupements végétauxde la France Mediterranéenne. Paris, France: CNRS. Brullo, S., & Marcenó, C. (1979). Dianthion rupicolae nouvelle alliance sud-tyrrhénienne des Asplenietalia glandulosi. Documents Phytosociologique, 4, 131-146. Brullo, S., Marcenó, C, & Siracusa, G. (2004). La classe Asplenietea trichomanis in Sicilia. Colloques Phytosociologique, 28, 467-538. Brullo, S., Scelsi, F., & Spampinato, G. (2001). La vegetazione dellAspro-monte. Studio fitosociologico. Reggio Calabria, Italy: Laruffa Editore. Brullo, S., & Spampinato, G. (2003). La classe Asplenietea trichomanis in Calabria (Italia meridionale). Fitosociologia, 40, 5-22. Conti, F., & Bartolucci, F. (2009). Prime indagini relative al gruppo Galium lucidum (Rubiaceae) in Italia. In S. Peccenini, & G. Domina (Eds.), Gruppi critic! della Flora ďItalia. Firenze, Italy: Societa Botanica Italiana. Costa, J. C, Neto, C, Aguiar, C, Capelo, J., EspiritoSanto, M. D., Honrado, J.....Lousá, M. (2012). Vascular plant communities in Portugal (continental, the Azores and Madeira). Global Geobotany, 2, 1-180. Daumas, P., Quézel, P., & Santa, S. (1952). Contribution á 1'étude des groupements végétaux rupicoles d'Oranie. Bulletin de la Société d'His-toire Naturelle de lAfrique du Nord, 43, 186-202. Davis, P. H. (1951). Cliff vegetation in the eastern Mediterranean. Journal of Ecology 39, 63-93. https://doi.org/10.2307/2256628 de Bolós, O., & Molinier, R. (1958). Recherches phytosociologiques dans I'lle de Majorque. Collectanea Botanica, 5, 699-865. De Cáceres, M., Chytrý, M., Agrillo, E., Attorre, R, Botta-Dukát, Z., Capelo, J.....Wiser, S. K. (2015). A comparative framework for broad-scale plot-based vegetation classification. Applied Vegetation Science, 18, 543-560. https://doi.org/10.llll/avsc.12179 De Cáceres, M., Font, X., & Oliva, F. (2008). Assessing species diagnostic value in large data sets: A comparison between phi coefficient and Ochiai Index. Journal of Vegetation Science, 19, 779-788. https://doi. org/10.3170/2008-8-18446 Di Pietro, R., & Misano, G. (2010). Shrubland and garrigue vegetation in the Gravine gorges (Apulia region, south-eastern Italy). Acta Botanica Gallica: Botany Letters, 157,195-229. https://doi.org/10.1080/12538 078.2010.10516199 Di Pietro, R., & Wagensommer, R. P. (2008). Analisi fitosociologica su al-cune specie rare o minacciate del Parco Nazionale del Gargano (Italia centro-meridionale) e considerazioni sintassonomiche sulle comunitá casmofitiche della Puglia. Fitosociologia, 45, 177-200. Dimopoulos, P., Sýkora, K. V., Mucina, L., & Georgiadis, T. (1997). The high-rank syntaxa of the rock-cliff and scree vegetation of the mainland Greece and Crete. Folia Geobotanica, 32, 313-334. https://doi. org/10.1007/BF02804010 Dring, J., Hoda, P., Mersinllari, M., Mullaj, A., Pignatti, S., & Rodwell, J. (2002). Plant communities of Albania: A preliminary overview. Annali di Botanica (Rome), 2, 7-30. Dufrěne, M., & Legendre, P. (1997). Species assemblages and indicator species: The need for a flexible asymmetrical approach. Ecological Monographs, 67, 345-366. Foggi, B., Cartei, L., Pignotti, L., Signorini, M. A., Viciani, D., Dell'Olmo, L., & Menicagli, E. (2006). II paesaggio vegetale dell'lsola d'Elba (Arcipelago Toscano). Studio fitosociologico e cartografico. Fitosociologia, 43(suppl. 1), 3-95. Francini-Corti, E. (1966). Problemi di Fitogeografia della Puglia. Archivio Botanico Biogeografico Italiano, 43, 195-226. Gamisans, J. (1975). La vegetation des montagnes corses. (PhD thesis), University of Marseille, Marseille, France. Gamisans, J. (1976). La vegetation des montagnes corses. Phytocoenologia, 3,425-498. Gamisans, J. (1978). Remarques sur quelques groupements végétaux assurant la transition entre les étages montagnard et subalpin en Corse. Ecologia Mediterranea, 4, 33-43. Gamisans, J. (1991). Complements au prodrome de la flore corse ed. Geneva, Switzerland: Conservatoire et Jardin botaniques de la Ville de Geneve. Heywood, V. H. (1954). El concepto de asociación en las comunidades rupicolas. Anales del Institute Botánico A. J. Cavanilles, 11, 463-481. Horvat, I., Glavač, V., & Ellenberg, H. (1974). Vegetation Südosteuropas. Stuttgart, Germany: Fischer. Horvatič, S. (1934). Flora i vegetacija otoka Paga. Prirodoslovna Istraživanja, 19, 116-372. Horvatič, S. (1963). Vegetacijska karta otoka Paga s opčim pregledom vegetacijskih jedinica Hrvatskog primorja. Prirodoslovna Istraživanja Acta Biologica IV, 33, 3-187. Jankovič, I., Šatovič, Z., Liber, Z., Kuzmanovič, N., Radosavljevič, I., & Lakusic, D. (2016). Genetic diversity and morphological variability in the Balkan endemic Campanula secundiflora si (Campanulaceae). Botanical Journal of the Linnean Society, 180, 64-88. https://doi. org/10.1111/boj.l2359 Kent, M. (2012). Vegetation description and data analysis: A practical approach, 2nd ed. Chichester, UK: John Wiley & Sons. Lakusic, R. (1968). Planinska vegetacija jugoistočnih Dinarida. Glasnik Republičkog zavoda za záštitu primae i Prirodnjačkog muzeja u Titogradu, 1, 9-75. Loisel, R. (1970). Contribution á 1'étude des groupements rupicoles calci-fuges. Anales del Institute Botánico A. J. Cavanilles, 26, 165-196. Martinez-Parras, J. M., & Peinado, M. (1990). Ensayo sobre la vegetación rupícola basófila de la clase Asplenietea trichomanis en la provincia corológica bética. Acta Botanica Malacitana, 15, 193-202. McCune, B., & Grace, J. B. (2002). Analysis of ecological communities. Gleneden Beach, OR: MjM Software. Meier, H., & Braun-Blanquet, J. (1934). Classe des Asplenietales rup-estres. Groupements rupicoles. Montpellier, France: Prodrome des Groupements vegetaux fasc. TERZI et al. Mucina, L., Bultmann, H., DierGen, K., Theurillat, J. P., Raus, T., Čarni, A.....Chytrý, M. (2016). Vegetation of Europe: Hierarchical floristic classification system of vascular plant, bryophyte, lichen and algal communities. Applied Vegetation Science, 19(S1), 3-264. https://doi. org/10.1111/avsc.l2257 Mucina, L, & Theurillat, J. P. (2015). Descriptions and validation of the names of some high-rank syntaxa in the European Asplenietea tricho-manis and Polypodietea. Lazaroa, 36, 75-78. Musacchio, A., Pellegrino, G., Cafasso, D., Widmer, A., & Cozzolino, S. (2006). Aunique A.palustris lineage across the Otrantostrait: Botanical evidence for a past land-bridge? Plant Systematics and Evolution, 262, 103-111. https://doi.org/10.1007/s00606-006-0469-y Otýpková, Z., & Chytrý, M. (2006). Effects of plot size on the ordination of vegetation samples. Journal of Vegetation Science, 17, 465-472. https://doi.Org/10.llll/j.1654-1103.2006.tb02467.x Pérez-Carro, F. J., Diaz, T. E., Fernandez, P., & Salvo, E.(1989). Contribución al estudio de las comunidades rupícolas de la Cheilanthetalia maran-to-maderensis y Androsacetalia vandellii en la Peninsula Ibérica. Acta Botanica Malacitana, 14, 171-191. Pérez-Latorre, A. V, Galán de Mera, A., Deil, U., & Cabezudo, B. (1996). Fitogeografíay vegetación del sector Aljíbico (Cádiz-Málaga, Espaňa). Acta Botanica Malacitana, 21, 241-267. Pignatti, S. (1982). Flora d'ltalia. Bologna, Italy: Edagricole. Quézel, P. (1964). Vegetation des hautes montagnes de la Grěce méridi-onale. Vegetatio, 12,289-386. https://doi.org/10.1007/BF03026056 Rivas Goday, S., Borja Carbonell, J., Monasterio Fernandez, A., Fernández-Galiano, E., & Rivas Martinez, S. (1956). Aportaciones a la fitosociología hispánica. Anales del Instituto Botánico A. J. Cavanilles, 14, 434-501. Rivas-Martínez, S. (1960). Roca, clima y comunidades rupícolas. Sinopsis de las alianzas hispánicas de Asplenietea rupestris. Anales de la Real Academia de Farmácia, 26, 153-168. Rivas-Martínez, S., Fernández-González, F, Loidi, J., Lousä, M., & Penas, A. (2001). Syntaxonomical checklist of vascular plant communities of Spain and Portugal to association level. Itinera Geobotanica, 14, 5-341. Rivas-Martínez, S., Penas, A., Diaz Gonzalez, T. E., Ladero Alvarez, M., Asensi Marfil, A., Díez Garretas, B.....Herrero, L. (2011). Mapa de series, geoseries y geopermaseries de vegetación de Espaňa (Memoria del mapa de vegetación potenciál de Espaňa) parte II. Itinera Geobotanica, 18, 5-800. Rodwell, J. S., Schaminée, J. H. J., Mucina, L., Pignatti, S., Dring, J., & Moss, D. (2002). The diversity of European vegetation - An overview of phytosociological alliances and their relationships to EUNIS habitats. National Reference Centre for Agriculture, Nature and Fisheries [Report no. EC-LNV 2002(054)], Wageningen, the Netherlands. Šilc, U., & Čarni, A. (2012). Conspectus of vegetation syntaxa in Slovenia. Hacquetia, 11, 113-164. Terzi, M. (2015). Numerical analysis of the order Scorzoneretalia vil-losae. Phytocoenologia, 45, 11-32. https://doi.org/10.1127/ phyto/2015/0009 Terzi, M., & DAmico, F. S. (2008). Chasmophytic vegetation of the class Asplenietea trichomanis in south-eastern Italy. Acta Botanica Croatica, 67, 147-174. Terzi, M., & Di Pietro, R. (2016). Nomenclatural remarks on the chasmophytic vegetation of the Centaureo-Campanuletalia. Plant Biosystems, 150, 1364-1369. https://doi.org/10.1080/11263504.2016.1149121 Terzi, M., Jasprica, N., & Cakovič, D. (2017). Xerothermic chasmophytic vegetation of the central Mediterranean Basin: A nomenclatural revision. Phytocoenologia, 47, 365-383. https://doi.org/10.1127/ phyto/2017/0185 Tichý, L, & Chytrý, M. (2006). Statistical determination of diagnostic species for site groups of unequal size. Journal of Vegetation Science, 17, 809-818. https://doi.Org/10.llll/j.1654-1103.2006.tb02504.x Tomič-Stankovič, K. (1970). Vegetacija Lovčena u Crnoj Gori. Zajednica naučnih ustanova Kosova, Studije, Knjiga, 17, 7-93. Trinajstič, I. (1964). Moltkea petraea (Tratt.) Gris. u biljnom pokrovu otoka Korčule. Acta Botanica Croatica, 23, 157-160. Trinajstič, I. (1980). Apercu syntaxonomique de la vegetation des rochers de I'espace Adriatique. Studia Geobotanica, 1, 203-213. Trinajstič, I. (2008). Biljne zajednice Republike Hrvatske. Zagreb, Croatia: Akademija Šumarskih Znanosti. Trotter, A. (1912). Gli elementi balcanico orientali della flora italiana e I'ipotesi della Adriatide. AW del Reale Istituto d'lncoraggiamento di Napoli, 64, 155-271. van der Maarel, E. (1979). Transformation of cover-abundance values in phytosociology and its effects on community similarity. Vegetatio, 39, 97-114. Weber, H. E., Moravec, J., & Theurillat, J.-P. (2000). International code of phytosociological nomenclature. 3rd edition. Journal of Vegetation Science, 11, 739-768. https://doi.org/10.2307/3236580 Westhoff, V, & van der Maarel, E. (1978). The braun-blanquet approach. In R. H. Whittaker (Ed.), Classification of plant communities (pp. 287-399). The Hague, the Netherlands: Junk. https://doi. org/10.1007/978-94-009-9183-5 Wildi, O. (2010). Data analysis in vegetation ecology. Chichester, UK: Wiley-Blackwell. https://doi.org/10.1002/9780470664971 SUPPORTING INFORMATION Additional supporting information may be found online in the Supporting Information section at the end of the article. APPENDIX SI Data sources of releves included in the data set APPENDIX S2 Syntaxa represented in the NMDS ordination (Figure 3) APPENDIX S3 List of chorotypes used for the chorological spectra of associations APPENDIX S4 Indicator species (IndSp) associated with the clusters of releves indicated in the dendrogram (Figure 2) APPEN DIX S5 Diagnostic roles of indicator species, according to different literature sources APPENDIX S6 (a) Synoptic table of the Asplenietalia glandulosi. (b) Synoptic table of the Onosmetalia frutescentis and Centaureo-Campanuletalia Appendix S7 Results of MRPP (multiple response permutation procedure) How to cite this article: Terzi M, Jasprica N, Cakovic D, Di Pietro R. Revision of the central Mediterranean xerothermic cliff vegetation. Appl VegSci. 2018;21:514-532. https://doi. org/10.1111/avsc.l2386