S. coleoptrata is an indigenous species in the Mediterranean region, which is largely introduced by human activities throughout Europe, Asia, North America and South America (Andersson et al. 2005). In the Abrau Peninsula, the species occurs in the mesophitic and xerophitic forests and shrublands. It is also frequently recorded in urban sites.

This species is widespread in the Caucasus (Zalesskaja 1978). In the Abrau Peninsula, the specimens were collected from the leaflitter layer.

The most common and abundant species in the European part of Russia (Zalesskaja 1978). It is known from the Caucasus in the south to the Altai Mountains in the east. The species also occurs north of the Polar Circle (Zalesskaja 1978, Palmén 1988). In the Caucasus, it was found in the upper soil layer (0-10 сm) and, less frequently, in the leaflitter layer of coniferous and mixed forests. The species is also known from steppes.

This species is widespread in Central Asia, the Caucasus and the Crimea reaching the Chinese Karakoram in the east, and Greece and Romania in the west (Eason 1997, Stoev 2004). It is often found at high elevations, and shows preference for meadows, sometimes also recorded from caves (Zalesskaja 1978). In the Abrau Peninsula, L. ferganensis occurs in a wide range of habitats: from mountanious deciduous forests (e.g. Q. petraea, F. orientalis, C. caucasica forest) to P. mutica - Juniperus shrubland on dry slopes and open areas. The specimens were collected mainly from the upper soil and compressed FH layers, as well as under the bark of decaying trees.

L. forficatus is an eurytopic species, showing a pan-Holarctic distribution pattern, widely distributed from Great Britain to Turkey and Georgia, the eastern boundary of its range reaching the Ural Mountains (Zalesskaja 1978). The species has also been introduced in the Far East, Africa, North and South America, etc. (Zapparoli 2009). In the studied area, the species occurs in the leaf litter layer, under the stones and under the bark of dead trees in deciduous forests.

This species is known from mesophilous woodlands (e.g. beech and fir-beech forests) in Central Europe, Italy, Bulgaria, Greece, the southern part of Russia and Ukraine, including the Crimea (Zalesskaja 1978, Stoev 2004, Zapparoli 2009). In the Abrau Peninsula the species occurs in different habitats, from open areas to deciduous forests, where it inhabits top soil (0-20 cm) and leaf litter layers.

L. peregrinus displays a mostly Mediterranean distribution pattern. The species is known from Italy, Croatia, Montenegro, Serbia, Macedonia, Albania, Greece, Bulgaria, Russian and Georgian sectors of Caucasus. It is also introduced into Great Britain, Panama, Bermuda Islands, and South Africa (Zalesskaja 1978, Zapparoli 1992). In the Abrau Peninsula it inhabits litter and microbiotopes under the bark of dead trees of deciduous forests.

This South European species is distributed from Spain to Turkey and southern Ukraine (Askania Nova Biosphere Reserve). It is especially common in the Crimea Peninsula (Zalesskaja and Schileiko 1991, Zapparoli and Iorio 2012). The species has also been recorded in Central Europe and has been introduced into Great Britain and, probably, North America (Zapparoli and Iorio 2012).​ In the study area it was found beneath the stones and in the soil.

This Centralasiatic-European species ranges from Great Britain and Iceland in the north to Morocco and Turkey in the south and Uzbekistan and Tajikistan in the East. The species has also been introduced into North America, some Atlantic and Pacific islands (Zapparoli 2009), and is widespread in the Caucasus (Zalesskaja and Schileiko 1991). In the Abrau Peninsula, the species occurs in the leaf litter and soil layer, under the bark of dead broadleaf trees (Q. petraea, F. orientalis, C. caucasica) forests.

This species is widely distributed in the Mediterranean. It is common in Crimea and the Caucasus, known from Iran, Turkey and Middle Asia (Zalesskaja and Schileiko 1991, Zapparoli 2002). In the studied region, the species occurs almost exclusively in ecosystems with xerophytic sub-Mediterranean vegetation.

This species was originally described by Seliwanoff in the Crimea Peninsula (Seliwanoff 1884) and, until now, has been known as the endemic to Crimea. In the study area it was found mainly beneath the stones of deciduous forests.

C. caucasicus is a species with the Caucasian and eastern Anatolian distribution (Bonato et al. 2011). The species was found in compressed fermentation-humus (FH) layer and soil.

This species inhabits soil and litter layers of various forests in Russia and Ukraine surrounding the Black Sea. It is also known to occur in the Balkans and extends to the Carpathians in the north. Several records are known from some Aegean islands and Anatolia (Bonato et al. 2011).

D. conjungens is found in the Crimea, and also recorded in the Balkan Peninsula, throughout the entire Anatolia from the western coast and southern Sporades islands to the easternmost part of Western Armenia, northwards to the Pontic mountains and southwards to the Tauric mountains (Bonato et al. 2008).

In habitus, the studied material strongly resembles G. oligopus, although our localities are situated far away from the currently known range of the species. Until now, G. oligopus has mostly been known from the Alpine-Dinaric area, being also recorded in the Carpathians (Christian 1996, Dányi 2007). In the Abrau Peninsula, the specimens were found beneath stones.

P. ferrugineum is widely distributed through most parts of the Palaearctic (Palmén 1988, Simaiakis and Mylonas 2003). In Russia it is known from Southern to Far Eastern federal districts and from Murmansk region through Central Russia and Caucasus to Armenia. The species shows preference for various types of pine forests and for seashores, less frequently it is found in mixed and deciduous forests, steppes, meadows and agricultural areas (Zalesskaja et al. 1982). In the Abrau Peninsula it was mainly collected from the compressed FH layer and beneath the stones.

A common soil-dwelling European species, distributed from the Great Britain to Macaronesia and through the Mediterranean region to Rostov region of Russia (Zalesskaja et al. 1982, Bonato et al. 2005). S. nemorensis tends to occur in the soils of open areas, less frequently in coniferous and deciduous forests, steppes and agricultural landscapes (Zalesskaja et al. 1982). In the Abrau Peninsula, the representatives of the species were collected from the soil and beneath the stones.

P. trivittatus is known from Israel, western Turkey and Greece; P. aegeus is found in Rhodes (Short and Huynh 2010). The identification of these two species is extremely difficult. Due to their strikingly similar structural details, they could even be synonyms. The question of the taxonomic status of these two species remains open (Short and Huynh 2010). In the region, specimens were collected by way of whipping the branches of bushes and trees.

L. coecus is widespread throughout Europe, particularly in Eastern Europe with its distribution extending to Central Asia (Short 2015). In Abrau Peninsula, the species was collected from the soil and litter layers of various forest types.

This species is known from Colchis, Georgian and Russian parts of the western Caucasus (Golovatch et al. 2006). In the study area the animals were found in leaf litter, upper soil layers and under fallen twigs.

T. costata is known from parthenogenetic populations in Central and Eastern Europe, as well as in some areas in the Caucasus, while bisexual populations are restricted to southern Romania, the Balkans, Anatolia, Israel, most of the Caucasus, and Crimea (Golovatch 2008, Golovatch 2012). Quite often specimens are found in caves (Golovatch 2008). In the Abrau Peninsula, the species was collected from the upper soil and lower leaf litter layers.

The species distribution covers southern Russia, Abkhazia, Georgia, north-western Azerbaijan and eastern Turkey (Golovatch et al. 2015). H. roseum is known as a typical leaf litter dweller. In the Abrau Peninsula, some individuals were collected from the compressed FH layer densely colonized by saprotrophic mycelium. This may be due to the altered, siphon-like mouthparts of Hirudisomatidans, which are presumably used for uptaking fluid food (e.g. hyphal contents) (Read and Enghoff 2009).

N. kochii is recorded widely across the continent. It has been introduced to New Zealand, North and South America (Enghoff and Kime 2005). The habitats of Nopoiulus species are closely related to decaying wood. In the area, some individuals were collected from leaf litter in broad-leaf forests.

The species is known from Turkey, Armenia, Azerbaidjan, Georgia and southern Russia (Jensen et al. 2002, Enghoff 2006). In the area, it is strictly associated with decaying wood of fallen trees.

Identification of the above species was difficult as only females and juveniles were found. C. flexum is a common and abundant species in the Krasnodar region (Chumachenko, in litt.), it was also reported from Georgia, Stavropol region and the montane parts of the Republic of Adygea, Russia (Zuev 2014). In teh study area the specimens were collected from the thick layer of leaf litter, also from overmoistening sites, rarely under barks of fallen trees.

This is most likely a new species that requires description. All specimens were collected from the leaf litter and under barks of fallen trees in all types of broad-leaf forests.

J. colchicus is known from Turkey, Georgia, Abkhazia and the southern regions of Russia (Enghoff 2006, Zuev 2014). The specimens were collected from the leaf litter of broad-leaf forests.

M. rossicum is known from the south and center of European Russia, Crimea and the Caucasus, reaching Ural Mountains in the East (Golovatch 1992). In the region, the species was collected from the upper leaf litter layers.

P. krivolutskyi is mostly known from the Caucasus (Mauries et al. 1997, Mikhaljova and Golovatch 2004). In the study area, this species was collected from the deciduous forests with thick, fairly moist litter, where it builds burrows laid with dung.

This is most likely a new, yet undescribed species. The specimens were found in broad-leaf forests, under the bark of fallen trees and branches, rarely in leaf litter.

B. furcatus was described in the Northern Caucasus (Lohmander 1936), but the exact range of the species remains unknown. In the studied region, it occurs in broad-leaf (T. begoniifolia and F. orientalis) forests, mainly in the upper soil and the compressed FH layers.

The species is known from the western part of Turkey, Adsharia and Abkhasia (Enghoff 2006). In the Abrau Peninsula, it occurs in compressed FH layer of broad-leaf forests.

The species is widespread in the Caucasus (Stavropol and Krasnodar regions of Russia and Western Georgia), where it occurs in a wide range of habitats (Zuev 2014). In the Abrau Peninsula, it is frequently found in leaf litter, rarely beneath the stones, and under the bark of fallen trees.