Biogeography of the high mountain Lepidoptera in the Balkan Peninsula

Balkanic high mountains represent nearly all types of European vertical zonation. The elevation and vegetation character of the timberline and allied vegetation types (scrubs, tall vs short, closed vs. open rupicolous swards) but also the edaphic traits, etc. considerably influence the biogeographical composition of butterfly and moth assemblages. The habitats of the high elevations are populated by several types of mountain species. They belong to five main biogeographical groups: (i) boreo-montane (“Siberian”) species, often represented by isolated, partly differentiated populations mostly in the coniferous forests zones; (ii) arctic-alpine (in majority Eurasiatic!) species represented by isolated, most often taxonomically differentiated populations in alpine zones of highest Balkanic mountains; (iii) alpine (nearly exclusively European!) species represented by isolated, mostly taxonomically differentiated populations in subalpine-alpine zones of Balkanic mountains; (iv) Balkanic-oreal species often with isolated populations (subspecies) also in the Southern or Southwestern Alps and Massif Central, in special cases also Appenines and/or in Southern and Eastern Carpathians, as well; (v) oro-Mediterranean-xeromontane species occurring in the southern Balkanic mountains, being either endemic or represented by differentiated subspecies of western Asiatic species. The most typical biogeographical patterns in butterflies and macro-moths are as follows: (i) close connections of the western Balcanic (Dinaric) populations of alpine and arctic-alpine species with southeastern Alpine ones; (ii) close connections of the eastern Balcanic (Thracian) populations of alpine and arctic-alpine species with southern Carpathian ones; (iii) the “Central Balcanic split” in taxonomic subdivision of several alpine and arctic-alpine species; (iv) the southern limit of distribution of boreo-montane, arctic-alpine and alpine species agrees with the “Adamovi ć -line”, i.e. the southern limit of the alpine type of vertical zonation of vegetation; (v) the northern limit of oro-Mediterranean xeromontane species also well agrees with this important line, since these species are connected with the oro-Mediterranean type of vegetation (partly by food plant specialisations, see: endemic Polyommatina or by rupicolous habitats, as some Noctuinae).

dense stands of Pinus montana. In the karstic high mountains also the zone-inversion is often observed in the cool, deep valleys or in karstic depressions (dolina, or called ponjikve in the Croatian mountains, Horvat 1959Horvat , 1962Horvat & al. 1974). On the other side, the more continental high mountains of Bulgaria, as Rila and Pirin exhibit a relatively high-lying limit of woody vegetation, formed by spruce and Balkanic coniferous trees as Pinus peuce (preferably on acidic substrate) or P. heldreichii (on calcareous substrate) followed by tall swards of Festuca paniculata and scrubby formation of Bruckenthalia spiculifolia and Daphne oleoides. Thus, the Balcanic high mountains show in limited dimensions nearly the complete diversity of European vertical zonation or "Stufenfolgen" (Adamović 1909;Horvat 1962;Walter & Straka 1970;Grabherr et al. 1994) of vegetation which shows at least four different major types in the European high mountains. In the Northern and Central Alps the Helvetic type of zonation predominates with a timberline formed by spruce (Picea abies), often with groups of Pinus cembra. In the continental Inner Alpine areas (e.g. parts of Wallis, Upper Engadin, parts of Ötztaler Alps) the Penninian type of zonation is widespread consisting of three different coniferous belts: a Scotch pine belt (often with birch), a zone of spruce and the highest level is predominated by larch (Larix decidua). In the Submediterranean zone either some variations of the Helvetic type can be observed, or the Insubric type of zonation occurs with sub-alpine beech or beechfir forests, often with inserted tall-grass or scrubby mountain steppe-like formations (parts of Pyrenées, Appenines, Insubric Alps, Dinaric Mts). Finally, the Mediterranean zone is characterised by special types of high mountain coniferous forests (e.g. Balkanic Abies species), scrubs, cusheon plant formations and dry grasslands of Oro-Mediterranean type. In the humid high mountains with the Helvetic and Penninian type of vertical zonation the high-lying open biomes are bordered, as a rule, by a nearly continuous timberline. In addition, the zonation of dense alpine scrub-and tall-forb communities ("Krummholz", scrub-like Pinus, Juniperus, Betula, Rhododendron and different Ericaceae) typifies the "kampfzone" of arboreal and nonarboreal biomes.
The occurrence of the arctic-alpine (e.g. Zygaena exulans, Pyrgus andromedae, Erebia pandrose, Glacies coracina, Grammia quenselii, Agrotis fatidica, etc.) and alpine species (e.g. Pyrgus cacaliae, Euphydryas cynthia, E. tyndarus-group, E. gorge, E. pronoe, Glacies canaliculata, G. noricana, G. bentelii, Apamea zeta, etc.) is usually connected with the Helvetic and/or Penninian types of vertical zonation. They need the presence of a "true" alpine elevation with adequate types of vegetation, as the alpine turfs: "Matten", cusheon plants, dwarf scrubs of lattice ("Spalier") vegetation, etc. They reach a southern boundary of occurrence in the Balkan peninsula at the "Adamović-line" due to the basic change of vertical zonation (Varga 1975(Varga , 1977b(Varga , 1995aVarga 2003; Fig. 1). The vertical distribution of Balkanic oreal species shows several characteristic differences as opposed to the alpine and arctic-alpine species. They are most numerous at the timberline. Their preferred habitats are grasslands in the upper subalpine belts. Only some few species are connected to the (mostly lower!) alpine elevations (2000-2400 m), and they exceptionally also occur at lower altitudes below the timberline (Coenonympha rhodopensis, Erebia orientalis, E. rhodopensis, Aplocera simpliciata). Some other species display a transitional character: they predominantly occur in lower-alpine and sub-alpine elevations with a mosaic-like scrub and grassland vegetation (e.g. in the Pirin Mts: Pinus mugho and Juniperus sibirica scrubs, Bruckenthalia spiculifolia and Daphne oleoides dwarf scrubs and grassy vegetation predominated by Festuca paniculata and Stipa spp.), or in steppe-like grasslands with abundant tall-forbs. Typical species of this vegetation type are e.g.: Polyommatus eroides, Boloria graeca, Erebia ottomana, Aplocera lithoxylata, Xestia ochreago, while other species occur mostly in humid sub-alpine meadows and tall-forb habitats, e.g. Lycaena candens. Some Balkanic oreal species but mostly the xeromontane species ( (Varga 1975(Varga , 1996Schmitt and Varga 2009).

The influence of the substrate and habitat type on the vertical distribution
The vertical distribution of butterflies and moths is generally influenced by substrate type and by the vertical belts of vegetation. The occurrence of some arctic-alpine species, e.g. Melanarta melanopa rupestralis, Pyrgus andromedae seem to be connected with the tundra-like geomorphological formations, as skeletic soils with Dryas octopetala-cusheons, e.g. in Pirin Mts. Many species prefer the slopes covered by erratic blocks or gravel. The apparent petrophily of several alpine and arctic-alpine species correlates with their sheltering behaviour under harsh weather conditions, e.g. in daily active geometrid species, as Pygmaena fusca, Sciadia tenebraria and all species of the genus Glacies or some Titanio species (Pyralidae).
The food plants of arctic-alpine butterflies and moths often are cusheon plants and low herbaceous plants such as species of Androsace (e.g. Elophos and Glacies spp.), Dianthus, Gentiana, Plantago (e.g. Euphydryas cynthia), Silene and Viola (e.g. Boloria pales), or grasses (e.g. Erebia spp. and Apamea spp.). Special substrate and/or vegetation types can also provide shelter from cold and rain; e.g. in high altitudes of Pirin Mts (Bulgaria) Pyrgus andromedae was observed hidden under cusheons of Dryas octopetala. We also have observed that Boloria pales, Euphydryas cynthia, Erebia euryale, E. orientalis, E. oeme and E. rhodopensis regularly shelter and overnight within dwarf scrubs of Juniperus nana where the minimal night temperatures are much milder than in open sward or scree. Other species, e.g. Erebia gorge, E. melas, Entephria nobiliaria, Glacies coracina, etc. regularly shelter under stones on screes (Varga and Varga-Sipos 2002).
The habitat preferences of alpine species are rather diverse. The more diverse vegetation of limestone mountains is usually home to a higher number of alpine species of Lepidoptera than that of the mountains consisting of acidic rocks. Examples include for instance the calcareous Belanské Tatry vs. the granitegneiss High Tatra of the western Carpathians: Erebia pharte, Calostygia austriacaria and Glacies noricana occur only in the calcareous Belanské Tatry. The calcareous conglomerate summits of the Bucegi Mts. are inhabited by much more alpine species than the granite-gneiss Făgăraş Mts. in the Southern Carpathians. Glacies coracina, G. noricana and Grammia quenselii e.g. occur only in the Bucegi massif, Erebia pronoe regalis and Pyrgus andromedae in Bucegi and in the calcareous massif of Piatra Craiului, Zygaena exulans in Bucegi and Ciucas Mts. Similarly, Entephria nobiliaria, E. cyanata, Glacies coracina and Pyrgus andromedae occur only in the calcareous Vihren-Kutela group and are lacking in the granitic parts of the Pirin Mts. (Varga and Varga-Sipos 2002). Some species with typical alpine distribution occur mostly in the humid sub-alpine or lower alpine grasslands near to the timberline, e.g.: Erebia manto, E. pharte*, E. eriphyle*, E. melampus*, E. sudetica*, E. albergana, Psodos quadrifaria*, etc. The species with * do not occur in the Balkanic high mountains, probably because of the lack of suitable habitats and also the others have a rather limited distribution only. Outside the Alps, some of these species (Erebia manto, E. pharte, E. sudetica, Psodos quadrifarius) occur also in similar habitats of the Carpathians. The only species which is fairly widespread both in the Carpathians and in the western Balkans is E. epiphron. Its sister species, E. orientalis exclusively occurs in the eastern Balkanic high mountains (Fig. 2) and is subdivided into three subspecies: E. o. orientalis in the Rila, E. o. infernalis in the Pirin Mts. and E. o. macrophthalma in the Western and Central Stara Planina). Erebia manto (as E. manto osmanica) occurs exclusively in the Dinarids of Bosnia, E. albergana (as E. albergana phorcys) at moderate altitudes (1200-1600 m, exceptionally from 700 m) near to the beech-forest timberline, on the southern slopes of the Western and Central Stara Planina and in the Korab Mts. while E. oeme is one of the most widely distributed Erebia in the subalpine-alpine levels of the Balkanic high mountains, although it is extremely localised and scarce in the Carpathians (Retezat, Făgăraş Mts.). There are relatively few alpine-subalpine butterfly species in the Balkan peninsula which are connected with the rocky and gravelly habitats with scarce vegetation, e.g. E. gorge (widespread in European high mountains, Fig. 3), E. melas (Balkans, northwestern Dinarids: Nanos, Southern and Eastern Carpathians, Mti Apuseni, Fig. 4); but also several species of the Geometrid moth genera Glacies, Elophos and Charissa (Geometridae) prefer these habitats Moucha 1956, 1958;Varga 1975Varga , 1996Varga , 2003Varga and Varga-Sipos 2002;Schmitt and Varga 2009).

Habitat partitioning in closely related species
The vertical distribution of butterflies is probably influenced also by the competition of closely related species. We only have very scattered data on the butterfly assemblages (e.g. the publications of Balletto et al. 1977;1992a, 1992bRákosy 1992a) and on the horizontal vs. vertical dispersion of butterflies in the European mountains (Varga and Varga-Sipos 2002). The interpretation of vertical shifts is based mostly on anecdotic informations and only rarely on the analysis of abiotic vs. biotic factors. It would be necessary to form a data-basis from literary and museal data, and to compare it with the results of recent surveys, carried out in high mountains of different geographical latitudes. Closely related species often show different types of habitat partitioning. A humid vs. dry habitat partitioning, combined with some vertical shifts, is characteristic for the sibling species of the Boloria pales-species group (Fig. 5). A typical sward vs. gravel partitioning has been observed e.g. in Erebia rhodopensis (grasslands) and E. gorge (gravel) in several Balkanic high mountains (Fig. 6). The vertical distribution of the alpine species displays a characteristic geographical trend. While they often occur in the Alps and Carpathians near and not exclusively above the timberline, their distribution is shifted essentially higher in the Balkan mountains (Drenovsky 1925(Drenovsky , 1928Rákosy 1992aRákosy , b, 2013Varga 1975Varga , 2003Varga and Varga-Sipos 2002; Table 2). They do not occur at the sub-alpine meadows, at the clearings of the uppermost coniferous zone or of the 'krummholz' belt. These habitats are regularly populated by the Balkanic oreal group of species. The Balkanic oreal butterfly species mostly populate the tall-grass dry or mesic grasslands near or over the timberline (e.g. Festucetum paniculatae, Stipa grasslands), e.g. Boloria graeca, Erebia orientalis, E. rhodopensis, E. ottomana as do also numerous typical Balkanic bush-cricket species such as Psorodonotus spp. and Anterastes serbicus. The Balkanic endemic Pinus species, P. heldreichii and P. peuce form light-penetrated, scattered stands and the Balkanic oreal butterfly and grasshopper species regularly occur in the natural clearings of these forests near to the timberline. At these elevations normally no arctic-alpine and alpine species occur. It is not clear, whether this is the consequence of the differences of the habitats or the effect of some kind of competitive exclusion or eventually both (Louy et al. 2014; Table 3, Fig. 7).
Some other Balkanic oreal species are connected with rocky habitats. The Erebia species show some interesting combinations of vertical and habitat type partitioning, i.e. swards vs. rocky habitats. The partitioning of the species of the Erebia pluto group (Warren 1936) and of the ecologically partly similar species E. melas is shown in five mountains (Fig. 6). In severeal areas of the Alps, Carpathians and Balkanic high mountains more species occur sympatrically, but usually with restricted habitat overlaps. E. cassioides neleus, for example, has a relatively wide sub-alpine to alpine range (1550 m -2100 m) in the Retezat Mts. where the Balkanic E. ottomana does not occur, while the Balkanic subspecies E. cassioides illyromacedonica and macedonica seems to be restricted to the alpine zone (2200 m -2600 m) in the Šarplanina, and also in the Rila and Pirin Mts., where the sub-alpine zone is occupied by strong populations of E. ottomana (Varga and Varga-Sipos 2002;Louy et al. 2014). The petrophilic Balkanic E. melas often shows a vertical exclusion with the taxonomically not very closely related alpine E. gorge in many Balkanic high mountains (e.g. in Durmitor, Šar-planina, Rila and Pirin Mts.). E. gorge is restricted to the alpine zone, where the montane/ sub-alpine E. melas does not occur. On the contrary, in the Olympus Mts., where no other Erebia spp. occur, E. melas occupies a wide range of rocky habitats, to the highest alpine levels (Fig.  6).  We cannot demonstrate based on these mainly anecdotic data the existence of competitive exclusion, however, there is a clear indication of some geographical trends.

Main faunal types and patterns of distribution
The Balkanic high mountains are inhabited by numerous characteristic butterfly and moth species belonging into the following five main biogeographical groups: (i) Boreo-montane species (Varga 1977b(Varga , 2010b (Fig. 10), E. albergana. Some species of the grassy or rupicolous alpine habitats show a rather wide Balkanic distribution, e.g. Boloria pales (Fig. 9), Erebia epiphron (Fig. 2), E. gorge (Fig.3), E. cassioides (Figs. 8, 10), E. pronoe, E. oeme. These species are -with the exception of E. epiphron -much more scarce and/or local in the Carpathians. It is typical that the Balkanic high mountains with the most extended alpine belts, e.g. Durmitor, Šar-planina, Rila, Pirin, support a more diverse assembly of Erebia species than the highest parts of the Carpathians. Other species are restricted to the highest western* and/or eastern + Balkanic mountains with long distance disjunctions, e.g. Pyrgus cacaliae, Euphydryas cynthia + (Fig. 11), Glacies canaliculata*, Orphne tenebraria*, Entephria nobiliaria, Gnophos obfuscatus (Varga 1975;Schmitt 2009;Schmitt and Varga 2009;Varga and Schmitt 2010 . 12). They are strictly connected to alpine elevations with glacial morphology and dwarf scrub and cusheon vegetation (Varga 1975;Schmitt and Varga 2009;Varga and Schmitt 2010). The endemic (Rila, Ossogova) Syngrapha rilaecacuminum is the sister species of the arcticalpine S. devergens.   (iv) The Balkanic-oreal species belong to the most typical members of the fauna of Balkanic high mountains. Most species of this group are quite generally distributed, e.g. Colias caucasica balcanica, Boloria graeca (Fig. 13), Erebia ottomana (Fig. 14), E. melas (Fig. 4), Coenonympha rhodopensis, while C. orientalis has a rather local distribution in the southern Dinaric mountains. Oppositely, the sister species of Erebia epiphron, E. orientalis* (Fig. 2) is restricted to the three eastern Balkanic high mountains Stara Planina, Rila and Pirin (Varga 1975;Schmitt 2009;Schmitt and Varga 2009;Varga and Schmitt 2010). E. rhodopensis* is the sister species of the SW alpine E. aethiopella and is very typical for the higher levels of the Balkanic high mountains (Fig. 15), Figure 11. Distribution of Euphydryas cynthia in Europe. c -Euphydryas cynthia cynthia; a -Euphydryas cynthia alpicola; l -Euphydryas cynthia leonhardi; d -Euphydryas cynthia drenovskyi. The population of the Rila Mts shows some parallel characters (e.g. reddish submarginal spots in males, less dichrous females) with the nominotypic subspecies. The population of the Pirin Mts is characterised by whitish submarginal spots in males and more dichrous colouration in females, as in the subspecies E. cynthia alpicola.
Briefly reviewing the main biogeographical connections, we can outline some general trends as follows.
(i) The western Balcanic (Dinaric) populations of alpine and arctic-alpine species show most often close connections with the southeastern (calcareous!) Alpine ones; (ii) Oppositely, the eastern Balcanic (Thracian) populations of alpine and arctic-alpine species regularly have close connections of with the Carpathian ones, often with direct links to the Southern Carpathians; (iii) The "Central Balcanic split" was observed in the taxonomic subdivision of several alpine and arcticalpine species; (iv) The southern limit of distribution of boreo-montane, arctic-alpine and alpine species agrees with the "Adamović-line", i.e. the southern limit of alpine type of vertical zonation of vegetation; (v) The northern limit of oro-Mediterranean xeromontane species also well agrees with this important line, since these species are connected with the oro-Mediterranean type of vegetation (partly by food plant specialisations, see: endemic Polyommatina or by rupicolous habitats, as some Noctuinae, mostly Noctuinae). These connections and splits will be analysed in details in the next paragraph.

Taxonomic subdivision of Balkanic high mountain species
Many morphological studies show close biogeographical connections but also discontinuities between (i) the western Balkan and the (ii) eastern Balkan mountain systems. These two systems are separated by the central Balkan depression along the rivers Vardar and Southern Morava, a typical migration route through the central Balkans (see below) . Good examples for these divergences are the fritillary Boloria pales (Fig. 9) as well as the ringlets Erebia pandrose and E. gorge (Fig. 3) (Varga 1975). Thus, the wing patterns of B. pales clearly separate the populations from the western Balkan mountains (B. pales contempta) from the eastern mountain areas (B. pales rilaensis) (Varga 1972a(Varga , 1975; on the other hand, the oro-Mediterranean relative Boloria graeca (Fig. 13) is indistinguishable with its populations from Durmitor, Šar Planina, Grammos,    Varga 1972b). In Erebia cassioides, the high mountain ranges of the western and southern Balkans belong to the subspecies E. cassioides illyrica and illyromacedonica (Lorković 1953), whereas the populations of the eastern Balkans belong to the subspecies E. cassioides macedonica (Rila and Pirin) and kinoshitai (Stara Planina, Beshkov 1996) closely related to the southern Carpathian E. cassioides neleus (Fig. 10). A similar case in noctuid moths is represented by the sibling species Apamea michielii (western Balkans: endemic for the Durmitor, N-Albanian Alps, Jakupica und Šar Planina; Varga 1977Varga , 2010b and A. maillardi (eastern Balkans: Stara Planina, Vitosha, Rila, Pirin, but also most other high mountain systems of Europe, as Pyrenées, Alps, Carpathians). Scattered exclaves of Balkanic oreal elements exist in many montaneous regions of Southern Europe, most often differentiated from the Balkan populations on subspecific level (Varga 1975;Schmitt and Varga 2009;Louy et al. 2014), as in southern France, (e.g Erebia ottomana tardenota in Massif Central, Fig.  14), in different parts of the southern Alps (e.g. E. ottomana benacensis, Boloria graeca tendensis, Aplocera simpliciata), central Italy (e.g. Coenonympha rhodopensis italica), the southwestern Carpathians (e.g. E. m. melas, C. rhodopensis schmidtii, Aplocera simpliciata), the northwestern Dinarids (e.g. E. melas nanos), the eastern Carpathians (e.g. E. melas carpathicola) and the Apuseni Mts. (e.g. E. melas runcensis) (Fig. 4). However, no general pattern of these exclaves can be obtained so that all of them apparently represent individual (and thus specific) cases. The glacial refugial character of some southern Alpine regions is also supported by the occurrence of endemic species of other groups, e.g. flightless Coleoptera (Holdhaus and Lindroth 1939;Holdhaus 1954), Micro-moths (Sattleria spp., Huemer 1998 or Geometridae: Glacies spitzi, G. baldensis (Wolfsberger 1966(Wolfsberger , 1971Varga and Schmitt 2010). In the case of the exclaves in the southern and eastern Carpathians and also Mt. Apuseni a late glacial range expansion from the Balkanic mountains via the region of the Iron Gate into the southwestern Carpathians is probably the most likely scenario for this type of disjunction. However, further genetic studies are urgently needed to test this hypothesis, since only the Balcanic and Italian populations of Coenonympha rhodopensis were studied until yet (Louy et al. 2013). These surveys have shown that the disjunct range of C. rhodopensis at the Balkan Peninsula is most likely the result of a postglacial up-hill shift of its distribution.

Ecological vs historical explanations of patterns of distribution
The Balkanic mountain systems are nested in a system of biogeographical links among the European high mountain systems. Several of these links can be explained by the recent ecological constraints. Thus, also their distributional history can be hypothesised. Other connections are not evident and need to be studied in details (e.g. by molecular analyses) in the future. A predominant link exists between the Alps and the Balkan high mountain systems, but some of these elements are absent in the Carpathians (Varga 1975;Schmitt and Varga 2009). This pattern was observed in three eco-geographical groups: (i) high alpine and (ii) arcticalpine* species (e.g. Euphydryas cynthia, Fig. 13, Pyrgus andromedae*, Orphne tenebraria, Pygmaena fusca*, Melanarta melanopa rupestralis*, Fig. 12), cold-continental steppe species of high altitudes in Europe (e.g. Arctia flavia, Agrotis fatidica; like in some Orthoptera, e.g. Podismopsis relicta, Gomphocerus sibiricus, Aeropedellus variegatus), but also in some meso-hygrophilous species of lower altitudes (i.e. the subalpine level) (e.g. Boloria eunomia, E. albergana).
The interpretation of these distribution patterns is more or less obvious in the first two groups: The southeastern Alps and the Balkan high mountain systems are connected via mountain areas of lower altitude in the northwestern part of the peninsula; these most probably served as corridors (or even major retreats) linking both areas of high mountain systems during glacial conditions, demonstrated e.g. by the occurrences of Erebia styx trentae in the southeastern Alps, of E. stirius in the northwestern Dinarids (Nanos) and Velka Kapela (Lorković 1952), and of E. gorge vagana in the Velebit (Fig 3). With the postglacial warming, most of the alpine species disappeared from the lower northwestern Balkanic mountains and only survived in the Alps or also in the considerably higher and geographically more extended mountain areas of the western and south-central Balkans (E. gorge).
The lack of several alpine species in the Northern Carpathians might have two mutually exclusive reasons, but both might be true in single cases. (i) No glacial centres of survival existed in the region of the Northern Carpathians so that no postglacial retreat was possible into this region. This version may be preferable in the case of calcareous rocky and ravine habitats, which are restricted in the Carpathians (e.g. Belanská Tatry), but rather extended in the Dinaric mountain systems of the Balkan Peninsula. (ii) These species also could survive in the Northern Carpathian region and possibly could retreate into the higher mountain areas responding the postglacial warming, but their habitats became too restricted and fragmentad during the climatic optimum (i.e. the Atlanticum) since the high plateau-like surfaces are here also rather restricted, in contrast to some of the high mountain systems (Korab, Šar planina, Rila, Pirin) of the Balkan Peninsula with considerably higher elevations in average and also larger high alpine plateau-like areas. This latter argumentation is also supported by the fact that the plateau-like Bucegi massif in the southeastern Carpathians is much richer in alpine and arctic-alpine species (e.g. Zygaena exulans, Glacies coracina, G. bentelii, Grammia quenselii; Fig. 12) than the sharp ridge-like High Tatra or Fägäraş Mountains. However, the absence from the Carpathians is much more difficult to explain in the group of species typical for the subalpine level, as e.g. E. albergana, E. oeme (occurs locally in the Southern Carpathians only, see: Dinca et al. 2010;Rákosy et al. 2011) As these species prefer less extreme conditions, their habitats are even more abundant in the Carpathian region than at the drier Balkan Peninsula. Therefore, their absence or extremely restricted range in the Carpathians cannot be explained by recent or postglacial ecologic conditions, but more likely by much older distribution patterns and stochastic processes.

Refugia, centres of dispersal, phylogeography
Recently, numerous suveys were carried out for alpine species (reviewed e.g. in Schönswetter et al., 2005;Schmitt, 2009) and a considerable variety of distributional patterns has been demonstrated. Particularly well studied are the phylogeographic structures of high mountain plant species in the Alps (e.g. Stehlik et al. 2000;Schönswetter et al., 2003Schönswetter et al., , 2005Triebsch Schönswetter 2003), but also the Pyrenees and Carpathians are already mostly understood (Schmitt 2009;Ronikier et al. 2008;Ronikier 2011). However, large hyatuses of knowledge are still evident for the high mountain systems of the Balkan Peninsula, despite of the fact that this region has the highest diversity of smaller or larger high mountain systems and maybe the most variable connections to some other mountain systems of Europe, in particular to the southeastern Alps and southern Carpathians (Varga 1975(Varga , 2003. The high mountain systems of the Balkan Peninsula therefore represent a natural "laboratory" of evolutionary processes in mountain species (Louy et al. 2014). Despite of these circumstances, phylogeographic surveys on butterflies from the Balkan high mountain systems are still scarce.
The genetic data on the mountain forest species E. euryale indicate an extended glacial refugium in the eastern Balkans (Schmitt and Haubrich 2008;Varga 2008); refugial areas of this species in the western Balkan Peninsula are likely, but have not been studied so far. These data coincide with the high importance of this region as glacial forest refugia (Willis et al. 1995(Willis et al. , 2000Farcas et al. 1999;Wohlfarth et al. 2001;Björkman et al. 2003;Willis and van Andel 2004;Varga 2008). Furthermore, the populations from Bulgaria and the southern Carpathians are genetically undistinguishable, thus supporting the idea that the glacial distribution in Bulgaria was linked with the southern Carpathians, most probably via the hilly area around the Iron Gate, the passage of the Danube through the southwestern Carpathians (Schmitt & Haubrich 2008).
The arctic-alpine E. pandrose shows remarkable differentiation at the mtDNA level of its Bulgarian haplotypes from the populations of the Central Pyrenees, Alps and of Scandinavia; this supports a separate centre of glacial survival in the Rila Mts., possibly connected with the Carpathian populations (Varga 1975;Cupedo 2007;Schmitt 2009) and well separated from the large zonal distribution on the "Mammoth steppe" during the glaciations. The latter resulted in the postglacial colonisation of the most parts of theAlps, Pyrenees and Scandinavia  while the southeastern Calcareous Alps (Dolomites, Julian Alps, etc.) and the Dinaric high mountains were populated by a third main group, possibly related with the also relict-like E. sthennyo (Varga 1975, Cupedo 2007. The calcareous mountains of the Dinarids could serve both as served as retreats and/ or stepping stones to the southeastern Alps since calcareous substrates predominate in both regions. Erebia cassioides belongs to the most typical alpine butterfly species of the Balkanic high mountains but also of the southwestern Carpathians (Fig. 10). According to the most recent surveys (Louy et al. 2014) the level of differentiation among the Balkan populations of E. cassioides reaches a considerably high level, only achieved by mountain butterfly species or species groups with high genetic differentiation among regional groups (e.g. Erebia epiphron, Schmitt et al. 2006; Erebia melampus-sudetica group, Haubrich and Schmitt 2007; Coenonympha arcania-gardetta-darwiniana-macromma group, Schmitt and Besold, 2010). It means that the true alpine species, similarly to the arctic-alpine ones had a highly scattered pattern of distribution during the last glacial maximum on the Balkan peninsula and could survive mostly or exclusively in the moderately high elevations of the glaciated alpine massifs, thus often having a central Balkanic split not only in their range but also in the pattern of genetic and/or morphological differentiation (see: Boloria pales, Erebia epiphron-group, E. gorge, E. cassioides, E. pandrose).
Contrasting to the former group, the Balkanic oreal species generally do not show a similarly strong genetic differentiation among the Balkanic high mountains. Both Erebia ottomana (Louy et al. 2014) and Coenonympha. rhodopensis (Louy et al. 2013) show a relatively shallow differentiation in this region. Considerable splits seem to exist only in large-distance disjunctions as e.g. in Monte Baldo (E. ottomana benacensis) or Mt. Terminillo (C. rhodopensis italica). The recently started parallel survey of E. melas and E. rhodopensis will possibly show the role of habitat differences on phylogeographic patterns in two phylogenetically not very closely related species.
A rather special group of "mountain" species of the Balkan Peninsula is formed by those species occurring mostly or exclusively in the southern part of the peninsula (maintly in the high mountains of the Peloponnisos and southern Greece: e.g. Tymfi, Parnassos), often connected with rupicolous habitats dominated by thorny cusheon plant formations (Astragalo-Acantholimetalia alliance) widely distributed in the arid mountains of Asia Minor and Central Asia. These species do not occur in those mountain systems with the Central European vertical zonation (German: Stufenfolge) of vegetation due to the lack of suitable habitats (e.g. Colias aurorina, Dichagyris gracilis, Chersotis laeta, Ch. capnistis; Fig. 17). Therefore, their northern distribution limits practically coincides with the Adamović line ( fig. 1), i.e. with the southern boundary of the Central European vegetation type at the Balkan Peninsula (Horvat et al. 1974). These species most probably represent old preglacial relicts of the European fauna demonstrating the significance of the Aegean Land Arc for the faunal genesis of southeastern Europe (Varga 2012).

Aspects of nature conservation: are high mountain butterflies and moths threatened?
The arctic-alpine and also some alpine species are confined only to the highest parts of the Balkanic high mountains although they can locally occur in high numbers, e.g. Zygaena exulans in Durmitor, or Euphydryas cynthia, Erebia cassioides and Apamea zeta in Rila Mts. It is more frequent however, that they are not only strictly localised but also scarce as Pyrgus andromedae, Pygmaena fusca, Orphne tenebraria, Entephria nobiliaria, Melanarta melanopa rupestralis, Agrotis fatidica, etc. Their occurrences are generally restricted to some special types of habitats, as tundra-like cusheon (Silene acaulis, Androsace spp., Dianthus spp., Gentiana spp.) and dwarf scrub (Dryas octopetala, Salix reticulata, etc.) vegetation and do not reach a high number of individuals (Pyrgus andromedae, Melanarta melanopa rupestralis, Agrotis fatidica). Thus, these populations together with their habitats may become more restricted or even extinct due to climate warming in the future, especially near to the southern limit of alpine type vertical zonation. Other sources of threat are the growing pressure of alpine skiing in several Balkanic high mountains (extremely e.g. in the not protected part of the Šar-planina) and the expansion of Pinus mugho due to the abandonment of traditional grazing (e.g. on some plateau-like parts of the Rila Mts.). Thus, their categorisation is mostly Vulnerable to Data Deficient, the latter mostly in strictly localised species of hardly accessible habitats (e.g. Syngrapha rilaecacuminum or Glacies spp.).
Oppositely, the Balkanic oreal species are much less threatened. Their populations are generally, or at least locally rather strong, even of such Balkanic endemic species as Erebia orientalis or E. rhodopensis. They are hardly affected by the shift upwards due to warming since their habitats are extended tall-grass formations of Balkanic type which have a high resilience against summer aridity. They also need, however, a moderate grazing pressure in their habitats to reduce the expansion of Juniperus nana and/or Pinus mugho. Thus they are most often not threatened or characterised as Least Concern (see Abadjiev and Beshkov 2007;Beshkov, http://www.nmnhs.com/butterfly_areas_bg/species.php?). The occurrence of Mediterranxeromontane species is usually connected with special edaphic conditions, e.g. screes, ravines with abundant rupicolous grasslands. Such habitats are most often used for extensive grazing only or completely unused. Thus, these species are mostly threatened only by the small extension and fragmentation of their habitats, often connected with limited number of individuals (e.g. Agriades dardanus, Polyommatus aroanensis, Pseudochazara orestes, P. cingovskii). Unfortunately, the ecological information on such species is often scarce, espacially on the night active species, as the xeromontane Noctuinae moths (e.g. Rhyacia psammia, Chersotis, Dichagyris and Euxoa spp.).