The Endangered and Protected Carabus hungaricus Fabricius, 1792 (Coleoptera: Carabidae) in Bulgaria: Distributional Patterns and Conservation Status

Abstract

Carabus hungaricus Fabricius, 1792, is a protected Natura 2000 species included in Berne Convention and CORINE. In Bulgaria, it is listed in the Biological Diversity Act and Bulgarian Red Data Book. It is included in the standard form of only one protected area (BG0000322 “Dragoman”) with an ‘unfavourable’ status. This study shows a part of the results from the development of an Action Plan for the protection of Carabus hungaricus in Bulgaria. Data were obtained between 24 May 2021 and 10 December 2023 with the help of 252 pitfall traps from 42 plots. Carabus hungaricus was established in only seven of the sampling sites, with a total of 198 specimens. In those sites, we found 56 other carabid species belonging to 18 zoogeographical categories. The European–Asiatic steppe complex prevailed (30%). The European–Neareastern (17.5%), Palaearctic and European–Central Asian (10.5% each) zoogeographical elements were the most represented. The known range of the species in Bulgaria is limited to the karst steppes of the small mountains around the Sofia Basin. We add four new localities to the distributional map of C. hungaricus and update its altitudinal limit, elevating it to 1200 m. The species is highly vulnerable, strongly attached to the steppe biome and is stenotopic in relation to environmental conditions, thus requiring full conservation of its habitats.

1. Introduction

The ground beetles of the family Carabidae are amongst the most well-studied and widespread Coleopterans. The genus Carabus Linnaeus, 1758, is of a particular interest, both for scientists or amateur entomologists and collectors, and probably contains some of the most popular insect species on Earth. Ironically, at the same time, several Carabus species are red-listed, legally protected, and often endangered. Nevertheless, little is known about the biology and ecology of most beetle species, including these large and attractive carabids, most of which appear to be true habitat specialists.

Among them, the Hungarian ground beetle Carabus (Pachystus) hungaricus Fabricius, 1792 is a zoophagous, mesoxerophilous beetle, which is a stenotopic steppe species, endangered everywhere across its highly fragmented distribution range. It is spread from Central Europe to Eastern Siberia [1] and it is declining throughout its range, sharing the fate of the temperate grasslands, which are among the most threatened biomes on Earth [2].

In Europe, Carabus hungaricus is a Natura 2000 species present in only six of the Community countries. In each country, it has a very limited distribution and an unfavourable state of conservation except for Hungary, where it is widespread with a favourable state of conservation [3]. In Hungary, considered the species’ last stronghold, long-term monitoring has suggested that its population size is relatively stable, seeming large enough to ensure long-term survival. Also, overlapping generations contribute to the stability of the population. However, because of the fragmentation and size of its habitat, the population may require management and further monitoring [4].

Carabus hungaricus is very rare in Romania, with small populations strictly localised in the southwestern part of the country, and its area of occupancy and population size have been in decline in the last century [5]. Currently, the distribution of Carabus hungaricus in the country is scattered across four Natura 2000 sites far from each other, and there are still unidentified aspects of the Romanian populations [3]. Of particular interest to us is the discovery of the species in 2014 near the town of Murta, which falls within the Natura 2000 site ROSCI0045 “Coridorul Jiului” [2]. This locality is situated in a karst–steppe landscape near the river of Jiu, which flows into the Danube in the area opposite to the Bulgarian Kozloduy Island.

Populations in Serbia are localised and scattered in a small area, as well; along with the so far known localities in the Delibato Sands Reserve (in the lowlands of the Serbian Banat) and its vicinities, new C. hungaricus populations were recently found near the Serbian–Romanian border (in the same region) [6,7].

In Bulgaria, Carabus hungaricus is very localised, too. The Bulgarian population is geographically isolated from the two main distributional ranges of the species—the Pannonian and the Northern–Pontic. The known range of the species in Bulgaria is limited to the western part of the Sofia Basin and, in particular, the neighbouring parts of the Western Balkan Mountains. The localities known so far were between 500 and 800 m a.s.l., near Dragoman and near Petarch [1,8,9,10], but given the landscape in the region, the report from Petarch probably relates to incorrectly labelled specimens. Later, the species was collected near the villages of Beledie Han and Letnitsa [11]. Generally, its distribution seems limited exclusively to within the boundaries of the Natura 2000 Site of Community Importance (SCI) BG0000322 “Dragoman”.

Despite the fact Carabus hungaricus is a Natura 2000 species of community importance, we still have many questions regarding its populations in Bulgaria (and in Europe). The current investigation led to the discovery of some new localities and revealed that there are still gaps in the knowledge on the distribution of the species in the country.

This study shows a small part of the results of the work on the development of an Action Plan for the conservation of the endangered ground beetle species Carabus hungaricus in Bulgaria [12]. They were obtained during a three-year research in some xerophytic landscapes in the vicinity of the Sofia Basin in central–western Bulgaria. The aim was to assess the distribution and status of this protected steppe beetle in Bulgaria, and to identify and analyse the impacts and factors that may limit its distribution and populations’ size.

2. Materials and Methods

During the survey on the distribution and status of Carabus hungaricus in Bulgaria, we chose 42 sampling sites in Western Bulgaria (Figure 1), mainly in the Sofia Basin, its adjacent mountains (parts of the Western Stara Planina Mts. range) and a few parts of the Western Predbalkan/Forebalkan and Kraishte Region. The plots were situated in various habitats, because we aimed to cover all suitable biotopes for this steppe species and some similar and/or adjacent locations, thus establishing the borders of its distribution in the country. A total of 252 pitfall traps were set. They were made out of cut 2 l. plastic bottles, buried at the level of the ground surface and filled with 8% formaldehyde. Six traps were set in each sampling site, at about 12–15 m from each other. The average area of each sampling site was about 1.5 dka. The traps operated in the period between 24 May 2021 and 10 December 2023.

The collected specimens were identified by the senior author. Beetles were pinned or preserved in ethanol and stored in the first author’s collection. Part of the specimens were deposited in the collection of the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences, Sofia, upgraded in the frames of the project DiSSCo-BG (Distributed System of Scientific Collections–Bulgaria) funded by the National Roadmap for Research Infrastructures, Ministry of Education and Science of the Republic of Bulgaria, and supported by the project “MCCATF” (funded by the National Science Fund of Bulgaria under Grant contract number KП–06–H61/6–14.12.2022).

According to their zoogeographical belonging, the ground beetle species were classified in zoogeographical categories and complexes according to the classification adopted in the work of Teofilova & Kodzhabashev [13].

3. Results and Discussion

During the whole study period, a total of 15,333 individuals of ground beetles were identified, belonging to 184 species, of which about 30% were characteristic of the specific steppe biota. Carabus hungaricus (with 198 collected specimens) was found in only seven of the 42 sampling sites, and they all fall within the boundaries of the Natura 2000 site BG0000322 “Dragoman” under the Habitats Directive (Figure 2). These sites are located in the Chepan Planina (two sampling sites on the slopes of the mountain, situated at about 1015 and 1185 m a.s.l., NE Dragoman) and Tri Ushi Mountains (five sites between 646 and 925 m a.s.l., one NW Opitsvet vill., one NW Beledie Han vill. and three N Bezden vill.), both within the range of the Western Stara Planina Mts. Carabus hungaricus was not established in the Sofia Basin, Forebalkan and Kraishte Regions.

The results add four new localities to the distributional map of C. hungaricus in Bulgaria and provide new information about its altitudinal limit (the species had so far been known to be present up to 800 m a.s.l.), elevating it to 1185 m, just below the top of the Chepan Planina Mt. The species will most probably be found at the very top (Petrovski Krast Peak, 1206 m) as well. One of the collected individuals in this site, with untypically red tibiae, is presented in Figure 3.

A part of this same large research were also the contributions related to the discovery and reporting of some typical steppe species for the first time in Bulgaria: Amara (Percosia) pastica Dejean, 1831, A. (Parapercosia) taurica (Motschulsky, 1844) and Carabus (Tomocarabus) bessarabicus Fischer von Waldheim, 1823, with the newly described subspecies tangra Teofilova et al., 2025; in these studies, some of the currently discussed localities and co-occurring species of C. hungaricus were also mentioned [14,15,16].

3.1. Zoogeography

The Eurasian steppe biota is the successor of the Eocene (Paleogene) so-called ‘Ancient Mediterraneum’, see [13], and the modern steppe range extends from the Hungarian ‘Puszta’ to the west, to the Mongolian mountain steppes and northwest China to the east. In Bulgaria, the steppe biome is preserved in isolated fragmentary refugia north of the Stara Planina (Balkan) Mts., in the open areas of the Danubian Plain and Dobrudzha, in places unsuitable for agriculture. An exception is the karst steppes around Sofia, which represent the extreme southwestern limit of the biome. Evidence for the existence of this refugium is provided by all established species with a steppe range, though it is highly disruptive. The analysis of the zoogeographic categories in the studied area showed a high presence of typical steppe elements not only among carabids, but also among other biotic components, such as vegetation, amphibians, birds and small mammals.

In the seven sites where Carabus hungaricus was collected, we found 57 carabid species from 23 genera and 12 tribes. Beetles from the carabid complex established in these habitats belonged to 18 categories from the five main faunal types of Bulgarian carabids (Figure 4). The European–Asiatic complex prevailed (17 species, 30% of all). It was followed by the Northern Holarctic and European–Siberian complex (15 species, 26%) and the Mediterranean (sensu lato) faunal type (12 species, 21%). The European complex consisted of nine species (16%). The Endemic complex was represented only by two Balkan endemics: Amara (Xenocelia) bischoffi Jedlička, 1946 and Molops (Molops) rufipes Chaudoir, 1843, and two Balkan subendemics: Carabus (Pachystus) cavernosus I. Frivaldszky von Frivald, 1835 and Myas (Myas) chalybaeus (Palliardi, 1825) (7%).

According to our concept for the separation of the categories, see [13], the European–Asiatic complex includes mostly steppe species, the ranges of which lie between the Eurosiberian and Mediterranean zones; the Northern Holarctic and European-Siberian complex includes species distributed mainly in the northern regions of the Holarctic, mostly in Europe and Siberia; the Mediterranean complex includes species distributed in the region of the ‘Ancient Mediterraneum’; the European complex includes mostly forest-dwelling species connected to the middle and southern parts of Europe; the Endemic complex includes species with limited ranges. The greatest numbers of species were European–Neareastern (17.5%), Palaearctic and European–Central Asian (10.5% each) zoogeographical elements (Figure 4). These three zoogeographical categories were the richest in species also in the carabid complexes from the highly urbanised region of the city and surroundings of Plovdiv (Central Bulgaria, Thracian Lowland) and from the xerothermophilic region of the Eastern Rhodope Mts., but there they had different ratios [17,18].

It is difficult to qualitatively compare the species composition and the zoogeographical structure of the studied seven sites, given the preliminary results and the different periods of study in the separate habitats. However, the zoogeographical structures of each of the seven sites were similar, with a pronounced predomination of the European–Asiatic steppe complex; its share was more than 30% in all studied sites (Figure 5). Furthermore, the European–Neareastern zoogeographical elements were the most represented in all habitats. Their shares in different sites were between 23 and 30% of all collected species in the given site.

The high proportion of European–Asiatic steppe species is quite notable and emphasises the specificity of the stenobiont species studied here and its habitats. Of particular zoogeographic interest are the polarised (east–west) ranges of the most rare steppe carabid species in Bulgaria, including Carabus hungaricus, C. bessarabicus, Amara pastica and A. taurica, whose discovery in the study area was extremely surprising and unexpected. It is likely that the modern ranges of these species have been disrupted by strong anthropogenic encroachment in the form of the conversion of steppe habitats in central–eastern Europe and central Asia into agricultural lands, which has led to the polarisation and fragmentation of the former primary steppe range. Since the biome of temperate grasslands, and steppes, in particular, are among the most threatened and highly anthropogenically affected habitats, many of their typical inhabitants are in severe decline. This once again urges the need for the development and application of respective legislative and practical conservation measures.

3.2. Habitats

The entire studied region where the 42 sampling sites were located is very large (almost ¼ of the territory of Bulgaria) and encompasses a great variety of habitats; thus, assessing its flora and vegetation was not a goal of this study. However, our observations emphasised the similarity of the habitats in which Carabus hungaricus occurs in Bulgaria. Areas studied within this research represent the southernmost limits of distribution of the steppe fauna in Eurasia, and, in Bulgaria, the target species Carabus hungaricus is found only there (and not in all of the areas). The species is considered a stenotopic tall-grass steppe specialist [19]. The habitats in the seven plots where C. hungaricus was found in Bulgaria were quite similar, and three of them are shown in Figure 2. They were karstic steppes or steppe-like stony meadows at altitudes between 646 and 1185 m. The most significant plant indicators were the Dwarf almond (Prunus tenella Batsch, 1801 = Amygdalus nana L.), European dwarf cherry (Prunus fruticosa Pall.), Mahaleb cherry (Prunus mahaleb L.), Lilac (Syringa vulgaris L.) and Smoke tree (Cotinus coggygria Scop.). In several habitats (in the Tri Ushi Mt.), the steppe Fernleaf peony (Paeonia tenuifolia L.) was also found. Actually, our results demonstrated the strong attachment of C. hungaricus to the steppe biome and proved its stenotopic character in relation to environmental conditions as well. Habitat preferences of C. hungaricus showed that it is associated with a lack of anthropogenic pressure and of changes in landscape structure, vegetation, edaphotope and microclimatic characteristics.

Similarly, the habitats in the localities near the villages of Beledie Han (Tri Ushi Mt.) and Letnitsa (actually Chepan Planina Mt.) explored by Bekchiev et al. [11] were described as calcareous grasslands exposed to the south and covered with low-growth vegetation. In Hungary, the species occurs mainly in dry calcareous and acidic sand grasslands in lowland areas, and dolomite grasslands on hills [4,20]. It is known that in Romania, Carabus hungaricus prefers steppes with ruderal grasses and shrubs of Prunus spinosa L. and Crataegus monogyna Jacq. [5], as it has also been found in a Robinia pseudoacacia L. forest where the grassy vegetation was high and there was good soil cover, but also where the soil was exposed [3]. Furthermore, in Romania, C. hungaricus exclusively prefers habitats where the soils are sandy [3].

Habitats of C. hungaricus and other steppe species fall into the group of the dry grasslands, which, although supporting specific, distinct and unique flora and fauna, are vanishing rapidly, at least in Europe. They are highly fragmented and often too small to support viable populations of more specialised species [4], thus causing the local extinction of these vulnerable or endangered organisms. Such a decline in biodiversity requires urgent preservation and conservation efforts for these habitats.

3.3. Hypotheses for the Establishment of the Population of Carabus hungaricus

The karst steppes in the southern depressions of the Western Stara Planina Mountains, and the Chepan and Tri Ushi Mountains, in particular, have never been the subject of special faunistic studies before. Besides the stenotopic Hungarian ground beetle, many other steppe elements of different systematic groups have been found within our study area: the steppe carabids Carabus bessarabicus tangra [16], Amara pastica [14] and A. taurica [15], the Critically Endangered Big-bellied glandular bush cricket Bradyporus (Callimenus) macrogaster (Lefebvre, 1831) [21], the European spadefoot toad Pelobates fuscus (Laurenti, 1768) [22], the Steppe viper Vipera ursinii (Bonaparte, 1835) [23], the Ural field mouse Apodemus uralensis (Pallas, 1811) [24] and the Dobrudzha hamster Mesocricetus newtoni (Nehring, 1898) [25]. All mentioned species are logically distributed in northern Bulgaria—Dobrudzha, Ludogorie, the Danubian Plain and the northern Black Sea coast—where in the past, during the early and middle Pleistocene, conditions for the development of steppe fauna existed. The chain of the Stara Planina (Balkan) Mountains has limited the spreading of the steppe fauna, and the Iskar Gorge and the Black Sea coast have been the only natural ecological corridors. The absence of the above-mentioned species in the Trans-Balkan valleys excludes the possibility of the steppe fauna entering the area near Sofia through the Black Sea coast. The fossil steppe assemblages of small mammals around the Iskar Gorge are very well studied and clearly delineate the path of the steppe fauna from northern to southern Bulgaria, and more specifically in the vicinity of the Sofia Basin through a kind of ecological corridor [26,27,28,29,30].

In our study, we took into account the available information on the migration of the steppe fauna through the Iskar Gorge, and we set five sampling plots at the northern parts of the Western Forebalkan (in the Gorge), in the vicinity of the villages of Reselets, Breste, Kunino and the town of Cherven bryag, where we did not find Carabus hungaricus, but we found other interesting steppe animals such as Bradyporus macrogaster and Carabus (Lamprostus) torosus I. Frivaldszky von Frivald, 1835, species of the coastal steppes’ complex, which have been found in the same areas by the second author in the past (1990, 1995) (Kodzhabashev, pers. observations).

The locality in the Natura 2000 site ROSCI0045 “Coridorul Jiului”, near the town of Murta in Romania, where Carabus hungaricus was found in the spring of 2014 [2], is about 25 km from the Danube River, the border between Romania and Bulgaria. This again raised the question of the species’ occurrence in the Bulgarian part of the Danubian Plain. The Danube and its catchment area were an obvious corridor and refugium for the distribution of C. hungaricus until recently, before the period of severe anthropogenic degradation resulting in the destruction of natural steppe habitats by their conversion into arable fields and pastures.

In the 1980s, the late Prof. O.L. Kryzhanovskij proposed a hypothesis for the occurrence of the species in southern Dobrudzha (Northeastern Bulgaria), where there are other proven faunistic elements of the steppe biome [31]. Several studies of the carabid fauna were carried out in this area, e.g., [32,33], but C. hungaricus was not found. A similar study was carried out in the western part of the Danubian Plain [13], in an area opposite to the locality in Romania, and with a similar habitat landscape type, but the species was not found there either. If we assume that the Iskar River is a proven refugium and corridor for the steppe biota in the karst areas around Sofia, then perhaps, in the future, efforts to find the Hungarian ground beetle should be directed to all similar gorges crossing the entire Danubian Plain, where it is very likely to be found.

3.4. Conservation

Carabus hungaricus is a Natura 2000 species, protected by Council Directive 92/43/EEC (Annexes II and IV) and included in the Berne Convention (II) and CORINE; there are also many conservation and monitoring programmes running concerning this species, and the species is protected in most countries of occurrence. In Bulgaria, it is protected by the Biological Diversity Act (Annexes II and III) and is included in the second edition of the Bulgarian Red Data Book (2015) with the status “Vulnerable” (VU); with regards to the European legislation within the Natura 2000 network, C. hungaricus is included in the standard form of only one protected area (BG0000322 “Dragoman”). According to Natura 2000 Reporting [34], C. hungaricus has an unfavourable status in Bulgaria.

Carabus hungaricus is a stenobiont xerothermophilic steppe species; therefore, the threats to its existence are specific and numerous. The continuing disappearance of natural grass steppe-like formations in the western part of the Sofia field and in adjacent montane regions where C. hungaricus occurs is a probable reason for the decline in the species populations in Bulgaria. The main limiting factors resulting in the rapid degradation of steppe formations are as follows: the removal of grasslands for agricultural areas; unsustainable agriculture; unsystematic grazing of cattle; livestock ranching (without grazing); mining and quarrying practises; fires and firefighting; roads and highways (all paved/asphalt roads); afforestation in open lands [5,34]. The following could be also regarded as endangering factors: ongoing urbanisation near big cities, waste deposition, the building of industrial areas, sports (quad, motorcycling), and the afforestation of its habitat with Black locust (Robinia pseudoacacia), Scots pine (Pinus sylvestris L.) or European black pine (Pinus nigra Arn.), and cultivated hybrid poplar (Populus x hybrida) [20]. The decline in the distribution area of C. hungaricus and all steppe stenobionts is mainly due to the fragmentation or loss of habitats as a result of the development and intensification of agriculture (land cultivation) and the afforestation of natural grasslands, e.g., [3]. Without maintaining the open habitats by grazing, these could become spontaneously reforested with bushes or trees, causing the extinction of C. hungaricus [20]. Protection of ruderal vegetation between cultures and prevention of the use of insecticides are crucial conservation measures [5].

We identified several concrete threats to C. hungaricus in the region of study:

• Construction of quarries for the extraction of rock mass and mining of ore and other underground resources. At the present moment, there is a large quarry that is being built near the Dragoman Marsh, on the northern slope of the Tri Ushi. There are also five other quarries already functioning in close proximity to the Chepan Planina, and there are several other intentions for the further development of such investments, too;
• Construction of photovoltaic and wind power plants. There are proposed projects for a wind power plant on the Chepan Mountain, and a photovoltaic station on the Tri Ushi. The construction of these facilities will destroy the habitats, and during their operation, they will require the regular clearing of grasses and shrubs using herbicides and via other chemical means;
• Occurrence of fires during summer and autumn dry periods. A huge fire was recorded in the military range area at the Tri Ushi Mountain in 2023. During military training, the risk of fires is high;.
• Uncontrolled grazing of domestic animals. In both mountain areas, there are neighbouring settlements. Next to the Chepan Planina, in its western part, is the town of Dragoman, and at the foot of the mountain, there are livestock farms. In the eastern and northern parts of the Tri Ushi, there are territories fenced off with electro-pastures, where grazing takes place all year round;
• Afforestation with atypical and non-native tree species. Reforestation activities with Black pine (Pinus nigra) and Black locust (Robinia pseudoacacia) have been carried out in the lower part of the Chepan Planina Mountain;
• Disposal of domestic and construction waste and formation of unregulated dumpsites. Such infractions were regularly observed during this research;
• Excavation of the surface by treasure-hunters or for the building of training shelters in the military training ranges, in both regions.

Considering that Carabus hungaricus is a soil dweller, the main threats to its existence are related to the disappearance, degradation and fragmentation of natural or derived steppe herbaceous vegetation. At the same time, knowledge about the distribution, structure and status of the populations and biology of the species in Bulgaria is insufficient. Collecting more information would contribute to clarifying the future prospects for the species. Identification of the regularities in the spatial distribution of the species’ localities would help in developing a proper set of measures for the conservation or restoration of the adjacent habitats.

In the neighbouring country, Romania, given the small area of the existing habitats, the pressures and threats that they face and the national distribution of the species, the conservation of C. hungaricus requires special attention and urgent measures to preserve its population and habitats [3]. In Bulgaria, the reality is not too different, so it is of great importance for an adequate set of measures to come into operation. Hopefully, the development of the “Action plan for the species Carabus (Carabus) menetriesi pacholei Sokolář, 1911 and Carabus (Pachystus) hungaricus Fabricius, 1792 for the period 2023–2032”, funded by Operational Programme Environment 2014–2020 [12], represents a good start.

The conservation measures taken so far are confined by the fact that the two mountains where C. hungaricus lives are included in the Natura 2000 network (SCI BG0000322 “Dragoman”) and special and specific conservation objectives have been developed for this area, including those for the Hungarian ground beetle.

In the developed Action Plan, for the period 2023–2032, restrictive measures related to the conservation of the old and newly established localities and the use of traditional extensive practices keeping the karst steppe biome in an unchanged state, ensuring the existence of the entire steppe biota, were set. However, there are concrete measures that need to be taken:

• Research on the distribution and population status of the species;
• Elucidation of the phenological and ecological characteristics of the species in Bulgaria;
• Clarification of the genetic status of the Bulgarian population;
• Designation of three new protected areas, namely “Chepan”, “Tri Ushi—Polygon” and “Beledie Han”;
• Development of Management Plans for the Natura 2000 sites and Protected areas with a strict outline for the conservation of steppe habitats;
• Annual monitoring of the species according to a developed system of sampling sites and a methodology for the reporting of its status;
• Promotion of steppe habitats and development of routes and eco-trails in order to promote conversation, awareness, public consciousness and nature conservation education among local people and adolescents.

4. Conclusions

The analysis of the presence and status of the endangered and protected Carabus hungaricus in Bulgaria showed a complex set of patterns in the distribution of individuals and their accompanying assemblages of ground beetle species. The results proved that the current distribution of C. hungaricus in Bulgaria is, so far, confined within the boundaries of the SCI BG0000322 “Dragoman”. However, they introduced new points into the distributional map of the species in Bulgaria and provided new information about its altitudinal limit, elevating it to about 1200 m, just below the top of the Chepan Planina Mt. They also showed the strong attachment of the species to the steppe biome, as well as its stenotopic character in relation to environmental conditions, associated with a requirement for a lack of anthropogenic pressure and changes in landscape structure, vegetation, edaphotope and microclimatic characteristics.

The aim was to assess the distribution and status of this protected steppe beetle in Bulgaria, and to identify and analyse the impacts and factors that may limit its distribution and populations’ size. For the purposes of the biological monitoring and conservation of the species in Bulgaria, and Europe as a whole, it is necessary to conduct systematic and targeted surveys in areas where the presence of the species has been confirmed, but also in other suitable habitats. Sampling in the already known and new characteristic habitats is necessary and should be carried out to better study the population status. It would also help to identify new distribution locations in which to apply measures for the conservation of C. hungaricus and other stenobiont species.

All known localities of C. hungaricus in Bulgaria are situated in the karst steppes of the small mountains around (i.e., north of) the Sofia Basin. Since they are the southernmost areas from the range of the entire Eurasian steppe biome, the existence of the entire steppe complex in this border refugium is highly vulnerable and dependent on conservation measures, requiring full conservation, which can only be achieved by the designation of strictly protected areas. With this paper, we emphasise the urgency of habitat protection given the species’ stenotopic nature and the severe anthropogenic pressures present.