Contribution to the knowledge of cave-dwelling fauna from the Prokletije Mountains

Abstract

The article presents the results of the study on invertebrate fauna inhabiting caves in the Prokletije Mountains. This mountain range is located on the border of Montenegro, Albania, and Kosovo. During the expeditions to Albania in 2021 and to Montenegro in 2022-2023, 17 caves and one bauxite mine were visited altogether. All the studied caves are located very high, above 1,700 m a.s.l., where the temperature inside is low, and several are filled with ice or snow. During the Albanian expedition 102 arthropods have been collected altogether. Among these were 19 beetles (Coleoptera), 44 flies (Diptera), three crickets (Orthoptera), five millipedes (Diplopoda), 16 Opiliones, six spiders (Araneae), two springtails (Collembola), and one tick (Ixodida). During the Montenegrin expeditions 226 specimens belonging to ten groups have been collected: 119 flies (Diptera), 32 beetles (Coleoptera), 20 caddisflies (Trichoptera), 21 spiders (Araneae), 20 Opiliones, six millipedes (Diplopoda), four bristletails (Archeognatha), two crickets (Orthoptera), one pseudoscorpion (Pseudoscorpionida), and one isopod (Isopoda). Ten species we recognized as troglobionts, four as eutroglophiles, and 11 as subtroglophiles. Among the collected species, three are new to Albanian fauna and two to Montenegrin fauna.

Headnote

Abstract: The article presents the results of the study on invertebrate fauna inhabiting caves in the Prokletije Mountains. This mountain range is located on the border of Montenegro, Albania, and Kosovo. During the expeditions to Albania in 2021 and to Montenegro in 2022-2023, 17 caves and one bauxite mine were visited altogether. All the studied caves are located very high, above 1,700 m a.s.l., where the temperature inside is low, and several are filled with ice or snow. During the Albanian expedition 102 arthropods have been collected altogether. Among these were 19 beetles (Coleoptera), 44 flies (Diptera), three crickets (Orthoptera), five millipedes (Diplopoda), 16 Opiliones, six spiders (Araneae), two springtails (Collembola), and one tick (Ixodida). During the Montenegrin expeditions 226 specimens belonging to ten groups have been collected: 119 flies (Diptera), 32 beetles (Coleoptera), 20 caddisflies (Trichoptera), 21 spiders (Araneae), 20 Opiliones, six millipedes (Diplopoda), four bristletails (Archeognatha), two crickets (Orthoptera), one pseudoscorpion (Pseudoscorpionida), and one isopod (Isopoda). Ten species we recognized as troglobionts, four as eutroglophiles, and 11 as subtroglophiles. Among the collected species, three are new to Albanian fauna and two to Montenegrin fauna.

Keywords: Albanian Alps, troglobites, ice caves, caves, arthropods

Received 14 February 2025; Revised 14 April 2025; Accepted 15 April 2025

INTRODUCTION

The Balkan Peninsula is recognised as one of the world's foremost biodiversity hotspots for cave fauna (Culver et al., 2006; Zagmajster et al., 2008; Zagmajster et al., 2018, Deharverg et al., 2024). This distinction arises from a combination of natural processes and a comprehensive history of research in the region. Among the natural factors, geological features - particularly the region's relief and climate - have had the most significant influence on the origin of subterranean fauna. The Balkan Peninsula is a mountainous area dominated by the vast Dinaric Alps, as well as the smaller Pindus, Balkan, and Rhodope mountain ranges. The Dinaric Alps are primarily composed of limestone (which predisposes the area to karst phenomena), along with sandstone and dolomite. Consequently, a multitude of caves and crevices have formed, creating unique habitats. A second influential factor is long-term climate change. During the Neogene (Messinian salinity crisis) and Quaternary (Pleistocene) periods, temperatures dropped and aridity intensified, forcing many species to colonize new environments, including caves, where they adapted to life in these habitats (Culver 8s Pipan, 2010). The recognition of this area as a biodiversity hotspot is associated with a long history of scientific exploration which began in the Postojna Cave. In 1832, Schmidt published a description of the troglobitic beetle Leptodirus hochenwartii (Schmidt, 1832) from this cave. In subsequent years, many new species were described from Postojna (Polak, 2005). However, a considerable number of studies have also been conducted intensively in other areas of the Balkan Peninsula during the past two decades, including Croatia (e.g., Pavlek 8s Ozimec, 2009; Stojanovic et al., 2021; Lukic et al., 2023), Bosnia 8s Hercegovina (e.g., Delic et al., 2023), Serbia (e.g., Pavicevic et al., 2012), Slovenia (e.g., Polaketal., 2012; Polak 8s Pipan, 2021). Nonetheless, within the Dinaric Mountains, there remain many areas with numerous caves that have not yet been studied or have been poorly researched. One of them is the Prokletije Mountains (Albanian Alps), where our study focused on invertebrate cave fauna.

The research was conducted in two areas of the Prokletije Mts. The first one was situated in the Albanian territory (Fig. 1) and included five caves and one mine. Four of them were located in the massif in the south of the Valbona Valley. The elevation of the explored area ranged from approximately 1,800 to

STUDY AREA

The Prokletije Mountains are also known as the Albanian Alps. This mountain range is located on the border of Montenegro, Albania, and Kosovo (Fig. 1). It is the southernmost and the highest part of the Dinaric Mountains. The mountains are composed of limestone with layers of dolomitic limestone, dolomite, sandstone, and limestone breccia (Kicihska et al., 2023). The carbonate rocks, especially limestone, are predisposed to karst. This phenomenon is observed throughout the entire study area, both on the surface and underground (Fig. 2A-C). 2,100 m a.s.l. Two of the studied caves were relatively small, filled with ice or snow, and were named Shpella Akullt (Fig. 3A) and Ice Cave (Fig. 3B). Another two caves were huge and vertical, these were Shpella Sportive and Shpella e Valbones. The former one is a well-known cave that has been explored for many years by Polish expeditions (Fig. 3C). The latter one was discovered during an expedition in 2021 (Kocot-Zalewska et al., 2021). The exploration of this cave is still ongoing and is not finished. It is the deepest cave in Albania (Slupihska et al., 2023). The last cave in this area, Shpella Haxhisse, is situated in the north of Valbona Valley, in the Maja Thate Massif, and is very close to the Montenegrin study area. The elevation of the cave is ca 1,700 m a.s.l. The research also included one artificial object, i.e., a former bauxite mine.

The second part of the study area was situated in the east of the Ropojana Valley, in Montenegro (Fig. 1). The study was performed in twelve caves. Several of the studied caves were massive with horizontal and vertical corridors, such as System Zlotej, Wielka Mala Burza, Gigant, Niby Czarna. Some others were relatively small with almost horizontally developed corridors, such as Krysztalowa, Niebieska, Kozi Hokej, Oczy Kobry. The Lodowy Gigant Cave is an ice cave with upper and lower floors (Fig. 3D-E). The Tunel and Indiana caves were small shelters. The elevation of the studied caves was similar to that of the previous area, i.e., ca. 1,800 - 2,200 m a.s.l. Special attention should be given to the System Zlotej Cave. It is a cave system, which means that a few explored caves have been connected into one giant cave with several entrances. Nowadays, it is longer than 7,500 m and has an elevational range of approximately 500 m.

The system also includes Cedevita; however, in this research, it was treated as an independent cave due to its own entrance and long distance to the connection with Zlota Cave.

MATERIALS AND METHODS

Samples

The specimens have been caught using a direct searching method during both expeditions to Albania and Montenegro. The expeditions in which invertebrate cave fauna were studied took place between August 2021 and July 2023. All specimens were placed into plastic vials filled with 96% pure ethanol and labelled. Most caves have been visited only once. The cave's specific areas, like the entrance or deep zones, were rarely indicated on labels, except in exceptional cases. The collected samples were deposited in the Upper Silesia Museum in Bytom.

Data analyses

All collected specimens were determined using various identification keys and papers. For millipedes: Koch (1847), Stoeve Enghoff (2008), Antic 8s Makarov (2015), Antic 8s Akkari (2023); for spiders: Deeleman-Reinhold (1978), Nentwig et al. (2024). Individuals from the family Empididae were identified using the keys from the following publications: Becker (1889) and Engel (1918, 1939). Specimens belonging to the Heleomyzidae family were identified using various keys, especially those made by Czerny (1924) - mainly for species of the genus Suillia, and those made by Gorodkov (1970), especially for Heleomyza species.

Additionally, we performed molecular analyses for Anthroherpon taxi to ensure proper determination of the species, due to the vast diversity within the genus Anthroherpon (Njunjic et al., 2018).

The ecological classification was based on Sket's (2008) concept. In this framework, species inhabiting caves are divided into four groups: troglobionts (strongly associated with subterranean habitats); eutroglophiles (surface-dwelling species that can form permanent subterranean populations); subtroglophiles (surface-dwelling species that temporarily or seasonally enter caves); and trogloxenes (species that accidentally or occasionally enter caves).

RESULTS

During the Albanian expedition 102 arthropods have been collected altogether. Among these were 19 beetles (Coleoptera), 44 flies (Diptera), three crickets (Orthoptera), five millipedes (Diplopoda), 16 Opiliones, six spiders (Araneae), two springtails (Collembola), and one tick (Ixodida).

During the Montenegrin expeditions 226 specimens belonging to ten groups have been collected: 119 flies (Diptera), 32 beetles (Coleoptera), 20

DISCUSSION

In our study, we collected 41 taxa, including 29 determined species. This number appears low in comparison to the recognised fauna in many caves of the Balkan Peninsula. For example, in the Vjetrenica cave system in Bosnia and Herzegovina, a total of 182 animal species has been reported (Ozimec 8s Lucie, 2009), including 45 troglobionts and 48 stygobionts (Delic et al., 2023). In other caves of the region, although only highly specialised subterranean fauna have been analysed, the number of species remains higher (Culver et al., 2021) than in our study. It is worth noting, that none of the studied caves identified more than five troglobionts. On the Albanian side, four species were recorded in the Spella Sportive cave, whereas on the Montenegrin side, five species were identified in the System Zlotej cave. Nonetheless, among identified species, the vast majority are related

caddisflies (Trichoptera), 21 spiders (Araneae), 20 Opiliones, six millipedes (Diplopoda), four bristletails (Archeognatha), two crickets (Orthoptera), one pseudoscorpion (Pseudoscorpionida), and one isopod (Isopoda). The list of collected taxa is available in Supplementary Information,

Molecular analyses confirm the correct identification of Anthroherpon taxi (Miiller, 1913) individuals. The BOLD matches ranged from 98.93 to 100% similarity of our specimens to A. taxi COI barcode sequences.

to subterranean habitats. Ten species we recognized as troglobionts, four as eutroglophiles, and 11 as subtroglophiles. The particular taxa are discussed in the text below. Six species were recognized as trogloxenes. This group is represented by flies, spiders, diplopods, and ticks. These species were found in caves but near the entrance or in the bauxite mine. The tick Ixodes vespertilionis was found very deep in the cave (ca. -200 m), however, this species is strongly connected with bats, not with caves. Specimens classified at a taxonomic level higher than generic based on their morphology are likely not troglomorphic unless their unknown biology would support this.

However, there are a few reasons for these results. It should be noted that the studied caves have been visited only once, and only one collecting method was used. During the explorations, the hand-picking method was used to collect the arthropods from the walls of caves and the ice surface where they remained more or less motionless. This certainly did not allow us to know the species composition of the cavernicolous fauna. The most significant caves of Balkan Region such as Postojna, Krizna Jama in Slovenia, Vjetrenica in Bosnia and Herzegovina have been well-known for a long time, and research on them has been ongoing for many years (Hlavac et al., 2017). Thus, the recognition of cave-dwelling fauna is outstanding, and the number of collected species is excellent (Culver et al., 2021). Moreover, the study on cave dwelling invertebrates in Albania and Montenegro are certainly less intense than in other countries in Balkan Region. Thus, the fauna is poorly known, and the data need to be supplemented. Despite Montenegro being recognized as one of the biodiversity hotspots, so far, only 80 cave-dwelling species have been documented (Polovic, 2024). A similar situation is observed in Albania. The study concerns a small percentage of caves, and the research is conducted in a relatively short time (Komnenov, 2011, 2020; Dundarova et al., 2015).

Furthermore, all the studied caves in Prokletije Mts. are located very high, above 1,700 m a.s.L, where the temperature inside is low, and several are filled with ice or snow. These factors may also restrict the number of species and specimens inhabiting caves. The best-recognized caves mentioned above are situated at lower elevation, approximately 260-600 m a.s.L, and have warmer temperatures. Certainly, more comprehensive data on biodiversity would be highly valuable in further studies of the explored caves to estimate the overall missed biodiversity with greater accuracy, using various pitfall-trap sampling methods (Kozelet al., 2017).

Diptera represented the largest group of identified taxa, with Gymnomus caesius (family Heleomyzidae) as the most frequently collected species. Following this, Phaeobalia peniscissa (family Empididae), recorded solely as females, was noted, as well as Trichocera maculipennis (family Trichoceridae) and Diamesa bohemard (family Chironomidae).

Within the family Heleomyzidae, two species, which belong to the genus Gymnomus are rare and known from alpine zones and caves. Both species are cold-adapted flies. Gymnomus ceianui is newly recorded from Albania and is known as a typical European mountain species, recorded in caves as well (i.e., Tatra Mts.) (Papp & Woznica, 1993). The second species, Gymnomus troglodytes, was described from a single female specimens collected from a cave located in "Siidlichen Osterreich" (Dinaric Alps). The adult fly bears typical cave adaptations mentioned by Howard & Moldovan (2018) like: small eyes, very long antennae (Fig. 4A), pronotal seta absent, and big claws on the tarsi. It is a relatively young troglobiont, having fully developed wings (Fig. 4A). Although its immature stages are very poorly known and have not yet been described, the larvae are known to live in bat guano (Bezzi, 1914). According to known distribution, it is a Balkan endemic species, recorded only from some caves located in Bosnia and Herzegovina (Bezzi, 1914; Absolon & Landrock, 1932), Croatia (Roder, 1897; Bezzi, 1914), Montenegro (new record), and Slovenia (Joseph, 1882).

Regarding the family Empididae, only Phaeobalia peniscissa, which belongs to the subfamily Clinocerinae, has been recorded in the caves of the Prokletije Mountains. It is known only from Albania and Montenegro (Becker, 1889; Yang et al., 2007; Slowihska 8s Jaskula; 2020). While some Diptera families are well represented in cave environments, the family Empididae is poorly documented in terms of both species' diversity and abundance. To date, only five species from this family have been noted in European caves. One of them, Empis lutea Meigen, 1804, belonging to the subfamily Empidinae, has been recorded only from the cave located in the Fond-de-Vaulx valley in Belgium (Leruth, 1939). The remaining four species belong to the subfamily Clinocerinae. Two of them, Dolichocephala cavaticum Becker, 1889 and P. peniscissa, were described by Becker (1889). The former species was captured in a cave near Dubrovnik, while the latter was collected from a cave near Njegus (Becker, 1889). The next species, Kowarzia barbatula (Mik, 1880), has been recorded from caves in the Moravian Karst in the Czech Republic (Bezzi, 1907), while Dolichocephala irrorata (Fallen, 1816) has been documented from the Hohiere Cave in the Walloon region of Belgium (Leruth, 1939). Overall, in cave habitats, the family Empididae is predominantly represented by the subfamily Clinocerinae, whose members are generally confined to large, relatively clean, cool streams and rivers. Adults of this subfamily are common on emergent boulders and stones near the waterline. They can also be found on damp rock walls, often covered with moss, or in the spray zone on wet rocks associated with streams and waterfalls (Sinclair, 2008). Given these habitat preferences, it is possible that species from the family Empididae recorded from caves have been captured sporadically, usually near the cave entrances, and can be considered primarily as trogloxenes. Only D. cavaticum is regarded as an eutroglophile due to its regular occurrence in the deeper parts of caves (Leruth, 1939). We recognized P. peniscissa as a subtroglophile.

Trichocera maculipennis and T. regalationis represent the Trichoceridae family. Both species are widespread in Holoarctic and are often found in caves. However, T. maculipennis occurs from the entrance to the deeper parts of corridors during the whole year, while T. regelationis has been observed most often near the entrance (Krzemihska, 2021). Thus, T. maculipennis was recognized as eutroglophile and T. regelationis as subtroglophile.

Three families of beetles were recognized in the studied caves, there were Carabidae, Leiodidae, and Staphylinidae. Family Carabidae was represented by one species Neotrechus dalmatinus (Fig. 4B), which is a widespread species in Southern Dinarides (Winkler, 1926; Hlavac et al., 2017). It was found in one cave Shpella Huxhisse on the Albanian side. Genus Neotrechus is well known from this region (Janak 85 Morawec, 2018). However, N. dalmatinus was not mentioned in Albania (Hlavac et al., 2017), but other species were described. N. vonickai Janak 85 Moravec, 2018 and N. suturalis pentheri Winker, 1926 were collected from caves located to the west of our study area (Janak 8s Moravec, 2018). Family Leiodidae was also represented by one species Anthroherpon taxi (Fig. 4C, D). However, up to 45 specimens were collected. It is worth emphasizing that it was collected in most of the examined caves, and occurred along their entire length, from the entrance zone to great depths. This species is highly diversified. As many as eleven subspecies have been described from southern Dinarides. Ten are known from Albania and Montenegro, and one from Bosnia and Herzegovina (Hlavac et al., 2017). Both species N. dalmatinus and A. taxi are troglobites highly specialized to live in the subterranean habitat. The family Staphylinidae was represented by one specimen, that was caught in the entrance zone of the small cave Niebieska. It was not identified to the species range.

Diplopod species representing three different orders were collected. Apfelbeckia insculpta (order Callipodida) is a widespread species, trogloxenic in nature, which is confirmed by the presence of ocelli and a high level of pigmentation (Kime 8s Enghoff, 2011). Glomeris pulchra (order Glomerida) is a troglophile recorded from a large number of caves, as well as from woodlands and bushes on the surface (Attems, 1959; Kime 8s Enghoff, 2011). Macrochaetosoma bertiscea (Fig. 4E) (order Chordeumatida) is a troglobiont species described in 2015 from Gornica Pit, Montenegro (Antic 8s Makarov, 2015). It is pigmentless, blind, and has elongated appendages, like all members of the Macrochaetosomatinae subfamily (Antic et al., 2015). This is the first record of this species from the Albanian part of the Prokletije Mountains. Inversotyphlus ammirandus (order Julidae) is a recently described hydrophilous and troglobiont species, which is one of the few millipede species with highly modified mouthparts, presumably due to a filtering diet. It was described from Cave Ru, on the Albanian side of the Prokletije Mountains (Antic 8s Akkari, 2023). This is the first record of that species from Montenegro. There were also two taxa (one Julid and one Polydesmid), which could not be reliably identified due to being either juveniles or females.

The collected spiders are mostly subterranean species. Typical troglobionts are Troglohyphantes pretneri&nd T. lesserti (Fig. 4F) (Naumova et al., 2019; Komnenov, 2020). These species are characterized by small eyes or their complete reduction (Deeleman-Reinhold, 1978; Nentwig et al., 2024). Typical troglophiles include Stygopholcus montenegrinus, a species characteristic only for Albania and Montenegro, and Meta menardi, which is widespread in Europe (Naumova et al., 2019; Komnenov, 2020; Nentwig et al., 2024).

CONCLUSIONS

In summary, the Prokletije Mountains appear to be a promising habitat for cave-dwelling fauna, both in terms of species richness and species diversity. This area is worth continuing the study, especially in the ecological aspects of occurring subterranean fauna, terrestrial and aquatic as well. Nonetheless, it is necessary to design long-term studies in some caves with more comprehensive methods, which can help settle if this area has the potential to be the next subterranean biodiversity hotspot region or rather not. It is worth noting that ice caves are unique due to their large reserves of stored clean water, which, in the context of climate change (e.g., global warming), represent a reservoir of potential freshwater for ecosystems and communities in the studied and surrounding areas (Zorn et al., 2020). Further research will focus not only on understanding the unique biodiversity but also on examining the microclimatic conditions that determine the specificity of cold-adapted fauna inhabiting these environments.

ACKNOWLEDGEMENTS

We are grateful to the Speleologia Polska Foundation for giving a chance to participate in the expedition in 2021 and for ensuring formal permission to conduct research. We are particularly appreciative to Wielkopolski Klub Taternictwa Jaskiniowego for taking us on 2022 and 2023 for their expeditions and Agencija za zastitu zivotne sredine/Environment Protection Agency of Montenegro for permission to conduct the research. We would like to thank Dr Robert Rozwalka for determining spiders and Opiliones from Albania, and Dr Ivo M. Karaman (University of Novi Sad; Serbia) for helping with arachnids from Montenegro. We would also like to thank Sara di Ferrante for sharing the pictures and Krzysztof Najdek for sharing the topographic map of the Prokletije Mts. Special thanks to every participant of the expeditions for helping with collecting specimens. The molecular analyses were carried out using equipment of MCBR UO (International Research and Development Center of the University of Opole, Poland), which was established as part of a project co-financed by the European Union under the European Regional Development Fund, RPO WO 2014-2020, Action 1.2 Infrastructure for R8sD. Agreement No. RPOP.01.02.00-16-0001/17-00 dated 31 January 2018. We also thank the reviewers for their careful reading of our manuscript and their many insightful comments and precious suggestions.

Authorship statement: JKZ provided the idea of the article, field study, collected the data, wrote the text, prepared figures. IS determined the Empididae species, wrote the text, made the linguistic corrections. PD conducted molecular analyses, wrote the text. JB determined millipedes and wrote the text. DMSz determined arachnids, wrote the text. DSz identified arachnids, wrote the text. HMSz determined arachnids, wrote the text. AJW identified Heleomyzidae and other flies, wrote the text. PS determined beetles, overview the text.

References

REFERENCES

Absolon, K., Landrock, K., 1932. Eine neue eualpine hohlenbewohnende Fliege aus der Herzegowina. Konowia (Vienna), 11, 266-272.

Antic, D., Akkari, N., 2023. The genus Inversatyphlus Strasser, 1962, stat. nov. and Inversotyphlus ammirandus sp. nov., a new bizarre, highly modified troglobiotic millipede (Diplopoda, Julida, Julidae) from Albania, Balkan Peninsula. ZooKeys, 1184, 65-80. https://doi.org/ 10.3897/zookeys. 1184.113498

Antic, D.Z., Drazina, T., RaSa, T., Tomic, V.T., Makarov, S.E., 2015. Review of the family Anthogonidae (Diplopoda, Chordeumatida), with descriptions of three new species from the Balkan Peninsula. Zootaxa, 3948(2), 151-181. https://doi.org/ 10.11646/zootaxa. 3948.2.1

Becker, T., 1889. Neue Dipteren aus Dalmatien. Berliner Entomologische Zeitschrift, 33, 335-346.

Attems, C, 1959. Die Myriopoden der Hohlen der Balkanhalbinsel Nach dem Material der "Biospeologica balcanica ". Annalen des naturhistorischen Museums in Wien, 281-406.

Bezzi, M., 1907. Ulteriori notizie sulla ditterofauna delle caverne. Atti della Societa Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano, 46, 177-187.

Bezzi, M., 1914. Ditteri cavernicoli dei Balcani raccolti dal dott. K. Absolon (Brunn) (Seconda contribuzione). Atti della Societa Italiana di Scienze Naturali Milano, 53, 207-230.

Culver, D.C., Pipan, T., 2010. Climate, abiotic factors, and the evolution of subterranean life. Acta Carsologica, 39, 577-586.

Culver, D.C., Deharveng, L., Bedos, A., Lewis, J.J., Madden, M., Reddell, J.R., Sket, B., Trontelj, P., White, D., 2006. The mid-latitude biodiversity ridge in terrestrial cave fauna. Ecography, 29, 120-128.

Culver, D.C., Deharveng, L., Pipan, T., Bedos, A., 2021. An overview of subterranean biodiversity hotspots. Diversity, 13(10), 487. https://doi.org/10.3390/dl3100487

Czerny, L., 1924. Monographic der Helomyziden. Abhandlungen der zoologish-botanischen Gesellschaft in Wien, 15, 1-166.

Deeleman-Reinhold, C.L., 1978. Revision of the cave-dwelling and related spiders of the genus Troglohyphantes Joseph (Linyphiidae), with special reference to the Yugoslav species. Slovenska Akademija Znanosti in Umetnosti, Razred za Prirodoslovne Vede, Classis IV, Historia Naturalis (Prirod. Vede), 23, 1-220.

Deharveng, L., Bedos, A., Pipan, T., Culver, D.C., 2024. Global subterranean biodiversity: a unique pattern. Diversity, 16(3), 157. https://doi.org/10.3390/dl6030157

Delic, T., Pipan, T., Ozimec, R., Culver, D.C., Zagmajster, M., 2023. The subterranean species of the Vjetrenica cave system in Bosnia and Herzegovina. Diversity, 15(8), 912. https://doi.org/10.3390/dl5080912

Dundarova, H., Dedov, I., Ljubomirov, T., Zhalov, A., Deltshev, C, 2015. Preliminary research on the cave fauna in three caves in Lure Mountain (Albania). In: Calic, J. (Ed.), Proceedings of the 8th Symposium on karst protection, Pirot, p. 139-145.

Engel, E.O., 1918. Das Dipterengenus Atalanta Mg. (Clinocera 01). Deutsche Entomologische Zeitschrift, 1-80.

Engel, E.O., 1939. Empididae. In: Linder, E. (Ed.), Die Fliegen der palaearktischen Region. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, p. 105-152.

Folmer, O., Black, M., Hoeh, W., Lutz, R., VrijenhoekR., 1994. DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology, 3, 294-299.

Gorodkov, K.B., 1970. Helomyzidae (Heleomyzidae), Opredelitel nasekomyh Evropeiskoy chasti SSSR, 5(2), 306-325 (in Russian).

Hlavac, P., Perreau, M., Cepllk, D., 2017. The subterranean beetles of the Balkan peninsula. Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, 267 p.

Howarth, F.G., Moldovan, O.T., 2018. The ecological classification of cave cnimals and cheir adaptations. In: Moldovan, O., Kovac, L., Halse, S. (Eds.), Cave ecology. Ecological Studies, Springer, Cham, vol. 235, 41-67. https://doi.org/10.1007/978-3-319-98852-8 4

Janak, J., Moravec, P., 2018. A new species and a new record of Neotrechus from Albania (Coleoptera: Carabidae: Trechinae). Studies and Reports Taxonomical Series, 14(2), 391-396.

Joseph, G., 1882. Systematisches Verzeichnis der in den Tropfstein-Grotten von Krain einheimischen Arthropoden. Berliner Entomologische Zeitschrift, 26, 1-50.

Kicihska, D., Pawlak, J., Stienss, J., 2023. An attempt to identify source areas of clastic deposits from selected caves of the Prokletije Mountains (Montenegro): a mineralogical and U-series geochemistry approach. International Journal of Speleology, 52(2), 109-122. https://doi.Org/10.5038/1827-806X.52.2.2473

Kime, R.D., Enghoff, H., 2011. Atlas of European millipedes (Class Diplopoda), volume 1, orders Polyxenida, Glomerida, Platydesmida, Siphonocryptidae, Polyzoniida, Callipodida, Polydesmida. Fauna Europaea Evertebrata, 3, 1-282.

Koch, L.C., 1947. System der Myriapodem mit den Verzeichnissen und Berichtungen zu Deutschlands Crustaceen, Myriapoden und Arachniden, 1-10, p. 270.

Kocot-Zalewska, J., Polok, M., Slupihska, M., Pereswiet-Soltan, A., 2021. Wyniki dzialah eksploracyjno-kartograficznych i badah biospeleologicznych w jaskiniach otoczenia Doliny Valbony w Albanii. In: Urban, J. (Ed.), Materialy 55 Sympozjum Speleologicznego, Bartkowa, p. 61-62.

Komnenov, M., 2011. Preliminary report on the results of investigation on the cave spider fauna in the frame of international speleological expedition to Mountain Hekurave, south slope of Prokletije, Albania. Progressione, 57 (April), 144-146. http: / /www, boegan. it/ index. php?id=562

Komnenov, M., 2020. Subterranean spiders (Arachnida, Araneae) of Montenegro. The Montenegrin Academy of Sciences and Arts, Proceedings of the Section of Natural Sciences, 23, 119-169.

Kozel, P., Pipan, T., Sajna, N., Polak, S., Novak, T., 2017. Mitigating the conflict between pitfall-trap sampling and conservation of terrestrial subterranean communities in caves. International Journal of Speleology, 46(3), 359-368. https://doi.Org/10.5038/1827-806X.46.3.2123

Krzeminska, E., 2021. Key and atlas to the genus Trichocera Meigen in Europe (Diptera, Trichoceridae). Acta Zoologica Cracoviensia, 64(1), 157 p. https://doi.org/10.3409/azc.64.01

Leruth, R., 1939. La biologie du domaine souterrain et la faune cavernicole de la Belgique. Memoires du Musee Royal d'Histoire Naturelle de Belgique, 87, 1-506.

Loew, H., 1863. Gymnomus troglodytes, eine neue osterreichische Fliegengattung. Wiener Entomologische Monatsschrift, 7, 36-38.

Lukic, M., Fiser, C, Delic, T., Bilandzija, H., Pavlek, M., Komericki, A., Drazina, T., Jalzic, B., Ozimec, R., Slapnik, R., 2023. Subterranean fauna of the Lukina Jama-Trojama cave system in Croatia: the deepest cave in the

Dinaric karst Diversity, 15(6), 726. https://doi.org/10.3390/dl5060726 Naumova, M., Lazarov, S., Deltshev, C, 2019. Faunistic diversity of the spiders in Montenegro (Arachnida:

Araneae). Ecologica Montenegrina, 22, 50-89. https://doi.Org/10.37828/em.2019.22.5 Nentwig, W., Blick, T., Bosnians, R., Gloor, D., Hanggi, A.,

Kropf, C, 2024. Spiders of Europe. Version 08.2024.

Online at https://www.araneae.nmbe.ch [accessed on

August 11, 2024]. https://doi.Org/10.24436/l Njunjic, I., Perrard, A., Hendriks, K., Schilthuizen,

M., Perreau, M., Merckx, V., 2018. Comprehensive evolutionary analysis of the Anthroherpon radiation (Coleoptera, Leiodidae, Leptodirini). PLoS ONE, 13(6), eO198367. https://doi.org/10.1371/iournal.pone.0198367 Ozimec, R., Lucie, I., 2009. The Vjetrenica cave (Bosnia & Herzegovina) - one of the world's most prominent biodiversity hotspots for cave-dwelling fauna.

Subterranean Biology, 7, 17-23. Papp, L., Woznica, A., 1993. A revision of the Palaearctic species of Gymnomus Loew (Diptera, Heleomyzidae).

Acta Zoologica Hungarica, 39, 175-210. Pavicevic, D., Popovic, M., Komnenov, M., Njunjic, I., 2012. Diversity of arthropod fauna in caves and pits

of Kamena Gora (Serbia) and its surroundings. Fauna

Balkana, 1, 151-176. Pavlek, M., Ozimec, R., 2009. New cave-dwelling species of genus Troglohyphantes (Araneae, Linyphiidae) for

Croatian fauna. Natura Croatica, 18(1), 29-37. Polak, S., 2005. Importance of discovery of the first cave beetle Leptodirus hochenwartii Schmidt, 1832. Endins, 28, 71-80. Polak, S., Bedek, J., Ozimec, R., Zaksek V., 2012.

Subterranean fauna of twelve istrian caves. Annales,

Series Historia Naturalis, 22(1), 7-24. Polak, S., Pipan, T., 2021. The subterranean fauna of

Krizna Jama, Slovenia. Diversity, 13(5), 210.

https://doi.org/10.3390/dl3050210 Polovic, L., 2024. Biodiversity of Montenegrin caves. In:

Barovic, G. (Eds.), Speleology of Montenegro. Cave and karst systems of the world. Springer, Cham, 79-84.

https://doi.org/10.1007/978-3-031-49375-l 6 Roder, V., 1897. Uber die Dipteren Gattung "Gymnomus Low". Festschrift zur Feier des funfzigjahrigen

Bestehens des Vereins fur schlesische Insektenkunde in Breslau, 85-89.

Schmidt, F., 1832. Beitrag zu Krein's Fauna. Illyrisches Blatt, 3.

Sinclair, B.J., 2008. Systematics of New World Clinocera Meigen (Diptera: Empididae: Clinocerinae). Ottawa: NRC Research Press, 245 p.

Sket, B., 2008. Can we agree on an ecological classification of subterranean animals? Journal of Natural History, 42(21), 1549-1563.

Slowihska, I., Jaskula, R., 2020. First record of Wiedemannia Ijerkae Ivkovic et Sinclair, 2017 (Diptera: Empididae) from Albania with an updated checklist of aquatic dance flies occurring in the country. Oceanological and Hydrobiological Studies, 49(4), 421-427. https://doi.org/10.1515/ohs-2020-0037

Stoev, P., Enghoff. H., 2008. A revision of the millipede tribe Apfelbeckiini Verhoeff, 1900 (Diplopoda: Callipodida: Schizopetalidae). Steenstrupia, 39(1), 47-66.

Stojanovic, D.Z., Antic, D.Z., Makarov, S.E., 2021. A new cave-dwelling centipede species from Croatia (Chilopoda: Lithobiomorpha: Lithobiidae). Revue Suisse de Zoologie, 128(2), 425-438. https: / / doi. org/10.35929/ RSZ. 0054

Slupinska, M., Ridush, B., Pereswiet Soltan, A., 2023. International cave exploration and science expedition Albania Valbona 2023. Summary Report. In: Colzato, N. (Ed.), UIS Bulletin, 65(1-2), 49-51.

Winkler, O., 1926. Revision der Neotrechus-Arten. Koleopterologische Rundschau, 12, 81- 96.

Yang, D., Zhang, K., Yao, G., Zhang, J., 2007. World catalog of Empididae (Insecta: Diptera). China Agricultural University Press, Beijing, 599 p.

Zagmajster, M., Culver, D.C., Sket, B., 2008. Species richness patterns of obligate subterranean beetles (Insecta: Coleoptera) in a global biodiversity hotspot - effect of scale and sampling intensity. Diversity and Distributions, 14, 95-105. https://doi.org/10.1111/j. 1472-4642.2007.00423.x

Zagmajster, M., Malard, F., Erne, D., Culver, D.C., 2018. Subterranean biodiversity patterns from global to regional scales. In: Moldovan, O.T., Kovac, L., Halse, S. (Eds.), Cave ecology, Ecological Studies. Springer International, Cham, 195-227.

Zorn, M., Komac, B., Carrey, A., Hrvatin, M., Ciglic, R., Lyons, B. 2020. The disappearing cryosphere in the southeastern Alps: Introduction to special issue. Acta Geographica Slovenica, 60(2), 109-124. https: / / doi. org/10.3986/AGS. 9396