The ground beetles (Coleoptera, Carabidae) of southern Kuril Islands, Russia

Abstract Background We compiled a list of the ground beetles that have been confirmed to occur to date in the southern Kuril Islands, Russian Far East. The list includes 168 species, all of which are known from Kunashir Island and the species richness on the remaining islands ranges from 68 (Shikotan Island) to 21 species (Tanfil'eva Island). The species richness is shown to depend sublinearly on island area, this being unusual for island faunas (Triantis et al. 2011). New information A large part of data is published here for the first time on the records of ground beetles in the southern Kuril Islands with precise localities. This allows not only the taxonomic composition of the faunas, but also the composition of local faunas to be discussed.


Introduction
Starting with the paper by Kuwayama (1967), who listed 20 species of ground beetles in Kunashir Island, about fifteen studies containing information on the fauna of the islands have since been published. For example, Krivolutskaja (1973) listed 66 carabid species in Kunashir and 75 for the southern Kuril Islands in her monograph on the insects of the entire Kuril Archipelago, while Kryzhanovskij et al. (1975) recorded already 113 species.
Later, the data on the ground beetles of Kunashir were replenished even more. For example, the research of G. Sh. Lafer (Lafer 1989, Lafer 1992, Lafer 1996 increased the number of ground beetle species to 140, whereas as a result of a series of subsequent papers (Sundukov 2001, Sundukov 2008, Makarov and Sundukov 2011, Sundukov 2011, Sundukov 2013, Makarov and Sundukov 2014, already 158 species have been confirmed in the Island's fauna. Moreover, we predicted (Sundukov and Makarov 2016) that at least 170 ground beetle species could be found on Kunashir.
The Global Biodiversity Information Facility (GBIF) repository, aside from the general list of animal species of Kunashir (Kozlovsky et al. 2020) comprising 157 species of ground beetles (applying the modern understanding of a number of taxa), contained no information on the composition and distribution of the carabid fauna of the southern Kuril Islands.
The body of information accumulated so far makes it possible to discuss both the differences in the faunas of the individual islands studied and the heterogeneity of the species composition within Kunashir as the largest island.

Project description
Title: Carabidae of South Kuriles

Sampling methods
Study extent: The studies were conducted on the southern islands of the Kuril The climate of the southern Kuril Islands is moderate humid maritime, with a strong influence of the Sea of Okhotsk and the Pacific Ocean. The Islands are characterised by a harsh wind regime (with gusts up to 35-50 m/s), high rates of precipitation (1200-1500 mm per year), relatively mild winters and cool summers (average temperature of the coldest month is -5.6°C and of the warmest month, +15.5°C). Waters of the warm Soya current approach the Okhotsk coast of the Archipelago and the cold Kuril-Kamchatka (Oyashio) current approaches the Archipelago from the Pacific side.
Kunashir is the southernmost and one of the largest islands of the Great Kuril Chain. The terrain of the Island is mainly volcanic and it consists of three mountain ranges formed by four active volcanoes: in the northern part, the isolated Tyatya Volcano (1819 m a.s.l.) and the Ruruy Volcano (1485 m a.s.l.) as the highest place of the Dokuchaeva Mountain Ridge; in the central part, the Mendeleev Volcano (886 m a.s.l.); and the Golovnin Volcano (541 m a.s.l.) in the southern part. The mountain ranges are separated by isthmuses: Yuzhnokurilskiy and Sernovodskiy, which are composed of marine sediments and volcanic folded Neogene rocks. Kunashir, along with Iturup, has the greatest landscape diversity amongst the islands of the Kuril Archipelago. The dense river network is formed by numerous mountain and lowland rivers and streams, many of which have high temperatures and mineralisation content. Amongst the two dozen lakes on the Island, the largest freshwater lake in the Kuril Islands is Lake Peschanoe, while the largest thermal lake is caldera Lake Goryachee.
The vegetation of Kunashir is noticeably richer and more diverse than on the other islands of the Archipelago (Figs 2, 3). According to V. Yu. Barkalov (Barkalov 2009), 1087 species  water. There are no rivers, but only short streams with narrow depressed channels and swampy banks and two rather large freshwater lakes. The Island is completely devoid of forest vegetation. Its elevated shore banks are covered with dense herb meadows and wild rose thickets (Fig. 5a), while the central part and floodplains of streams are covered with sedge, reed or sedge-moss bogs (Fig. 5b).
c d e f  Yurii Island is located in the south of the Lesser Kuril Chain. The coastline is heavily indented, with deep bays over the entire extent of the western coast. The shores are mostly rocky. The terrain is formed by four undulating land massifs connected by low isthmuses. The height of the watersheds ranges from 20 to 30 m a.s.l., the highest elevation being 44 m a.s.l. The isthmuses are occupied by low-level swamps and small lagoon lakes. There are sand beaches in the larger bays, while the remaining shore is occupied by pebble or large-block beaches. There are only small streams with narrow channels depressed into the clay soil and swampy banks. There is no forest vegetation, the upland areas being covered with dense herb meadows (Fig. 5c) and the lowlands with sedge-moss bogs (Fig. 5d).
Tanfil'eva Island is the southernmost island of the Lesser Kuril Chain, located 5 km off the north-eastern coast of Hokkaido. The landscape is flat, with the greatest elevations reaching up to 16 m a.s.l. The coastline is strongly indented, forming wide bays and headlands that protrude far into the sea. Short streams and several lagoon lakes, the largest of which are located near the east coast, represent the hydrographic network of the Island. The relief and vegetation are similar to those on Polonskogo Island (Fig. 5e, f).

Traits coverage
Altogether, 168 carabid species are known to occur in the southern Kuril Islands, on the basis of both literature data and museum collections. We exclude four species (Table 1) from this list which are known from single records from Kunashir Island, as we later conducted large-scale surveys at the locations of those records, but obtained none of these species.  Figure 6.
Ground beetle collecting localities Table 1.

Species of ground beetles from Kunashir Island not included in the present study.
The ground beetles (Coleoptera, Carabidae) of southern Kuril Islands, Russia Thus, the richness of the ground beetle fauna of the southern Kuril Islands totals 168 species. All these species are known from Kunashir Island [there are records of five species of ground beetles from Shikotan Island which have not been found on Kunashir to date (Kryzhanovskij et al. 1975, Lafer 1989; however, none of those records has been confirmed by our material]. The faunas of ground beetles of the other Islands resemble versions of the fauna of Kunashir impoverished to varying degrees and ranging between 68 and 21 species (Table 2). We exclude data for the Zelenyi and Anuchin Islands from further analysis due to insufficient material. The number of species depending on island area (Fig. 7) is well approximated by the power function S = 9.0968 a (R = 0.9811). However, as the power coefficient is close to 1, the dependence does not differ from the linear one which describes the observed pattern just as well (R = 0.9748).
The obtained parameters of the classical power dependence S = Ca ( Sugihara 1981, Dengler 2009) are partially comparable with those known for the faunas of island beetles (Niemelä et al. 1987, Niemelä 1988, Browne and Peck 1996, Kotze et al. 2000, Fattorini 2002, Zalewski and Ulrich 2006, Trichas et al. 2008): C = 9.0968 (the cited publications report on values ranging from 0.525 to 11.321). However, the power coefficient Z = 0.9811 is significantly outside the range (0.06-0.449) indicated in the literature sources. Earlier, high Z values were suggested to indirectly indicate a large role of extinction processes (Fattorini and Borges 2012) in the formation of island beetle faunas. This is consistent to some extent with the history of Kuril Archipelago: the more ancient islands of the Lesser Kuril Chain are gradually decreasing in area under the impact of multidirectional tectonic processes (Razzhigaeva et al. 2009) and erosion (Markov 2009).
As we demonstrated earlier, the beetles of the Kunashir Island form at least two local faunas, "northern" and "southern", the border between both roughly corresponding to the Yuzhnokurilskiy isthmus (Makarov et al. 2013).
The features of the "northern" local fauna are determined by the endemic Bembidion ruruy Makarov et Sundukov, 2014, which we consider a rare case of a Pleistocene endemic to 2 0.9811 2 2 Z Table 2.
Island areas and the number of ground beetle species in the southern Kuril Islands.
the Kunashir fauna (Makarov and Sundukov 2014), as well as a number of ground beetle species known only from the Dokuchaeva Mountain Ridge or its spurs: Trechus nakaguroi Uéno, 1960, Bembidion lucillum lucillum Bates, 1883, Diplous sibiricus atratus Habu, 1951and D. depressus (Gebler, 1829. In addition, the Dokuchaeva Ridge is the only habitat for a number of vertebrate and insect species from different orders on Kunashir Island (Sundukov and Makarov 2016).
The fauna of the "southern" block is more heterogeneous. On the one hand, the endemic subspecies Cylindera elisae (Motschulsky, 1859) and Bembidion sanatum Bates, 1883 are known from the Mendeleev Volcano. On the other hand, the peculiarity of this fauna is determined by the species found in the very south of the Island and widespread in Japan (Bembidion yokahamae (Bates, 1883), Amara chalcophaea Bates, 1873), for which a recent (and possibly repeated) penetration into the Island seems to be most likely.

Data coverage of traits
The dataset  includes finds of 168 species on five islands of the Kuril Archipelago -a total of 1320 locations Temporal coverage Notes: 1990Notes: , 2008Notes: , 2009Notes: , and 2011Notes: -2018 years