CHAPTER 3

SECTION 5. Order COLEOPTERA

Family ELATERIDAE (click beetles)

Until recently the clickbeetle fauna of the Kuril archipelago had been minimally explored. There were no Soviet studies on this problem. Japanese investigators (Kano, 1933-1934; Miwa, 1929; Kuwayama, 1967) had cited 23 species of clickbeetles for the Kuril Range. The materials we had collected, published in a special article (Gur'eva and Krivolutskaya, 1968), have made it possible to increase the list of species to 49; 4 genera (Stenagostus, Miwacrepidius, Cryptophypnus, Paracardiophorus) have been added; 8 species and 4 genera (Mucromorphus and Miwacrepidius) have proven to be new for the fauna of the USSR and 1 species new to science. All the material we have at our disposal on the Kuril clickbeetles has been reviewed and identified by E. L. Gur'eva; she has described a new species, Hypnoidus (Ascoliocerus) kurilensis (Gur'eva, 1972). Information on the general distribution of particular species has been borrowed from catalogues (Yakobson, 1905; Winkler, 1924) and the papers of A. I. Cherepanov (1957), T. Kano (Kano, 1933-1934), G. Miwa (Miwa, 1934), and H. Blunck (Blunck, 1954). In addition, the distribution of some species was defined more precisely on the basis of ZIN AN SSSR collections.

At the present time, 49 species of clickbeetles, belonging to 20 genera, are known on the Kuril Islands: Stenagostus (1 species), Harminius (1),Miwacrepidius (1), Athous (1), Denticollis (1), Mucromorphus (1), Actenicerus (2), Anostirus (1), Selatosomus (7), Hypnoidus (3), Cryptophypnus (7), Dolopius (2), Sericus (1), Ectinus (4), Silesis (1), Ampedus (11), Hypnocoelus (1), Melanotus (1), Cardiophorus (1), Paracardiophorus (1). Of these, 37 species are cited on the basis of our data, 2 based on published data; 42 have been identified to species level and 7 only to genus level. The latter relates to nearly all the representatives of genus Cryptophypnus and 1 species from genus Ampedus. A large number of the species of these genera have been described by Japanese investigators; it is impossible to identify these reliably by existing descriptions. Some of the species described by Japanese authors will probably become synonyms, as has already happened in relation to Ampedus ainu Lew. and A. orientalis Lew., which have proven to be synonyms of A. pomorum Hbst.

It can seen from this list that only 4 genera which are widely distributed in the Palaearctic are represented by several species (from 4 to 11); the rest are represented by one to three species. The majority of the clickbeetles observed on the Kuril archipelago are rare; many have been encountered only once. Only 2 species can be regarded as relatively abundant and 4 as common. It does not seem possible, due the absence of regional compendia on the clickbeetle fauna of Sakhalin, Japan, and the continental Far East, to make a detailed comparison. But the rare incidence of the majority of the species and the absence on the archipelago of many widespread palaearctic genera (Adelocera, Lacon, Limonius, Agriotes, etc.) suggest an appreciable impoverishment of the Kuril elaterid fauna by comparison with adjacent territories.

The distribution of the clickbeetles over the territory of the Range is uneven; it is determined by historical and to a substantial degree climatological conditions, and coincides with the general patterns of the disposition of the entomofauna on the Kuril archipelago. Thus, 49 clickbeetle species have been noted on the southern islands (Kunashir, Iturup, and Shikotan), i.e., nearly the entire composition of the fauna, only 5 species on the northern islands (Paramushir, Shumshu), and in the central part of the Range, only 3 species on Urup and none on Simushir (possibly due the inadequate exploration of this island). Only 3 species, Hypnoidus litoralis Esch., Ampedus nigrinus Hbst., and A. latiusculus Rtt., have a wider distribution; they are encountered on all parts of the archipelago. Species mainly of the boreal complex (Holarctic, Transpalaearctic, and Beringian) are distributed on the northern islands, and Manchurian and Island species on the southern islands.

The numbers of species on the various southern islands vary in their turn; 37 clickbeetle species are known on Kunashir, of which 20 have been observed only for this island; on Iturup, 17 species, of which 5 have been observed only on that island; on Shikotan, 17 species, of which 4 have been observed only on that island; and 1 species only on Paramushir. There are four species encountered on three southern islands, 4 common to Kunashir and Iturup, and 6 common to Kunashir and Shikotan.

Thus, the clickbeetle fauna is most richly represented on Kunashir, and southern forms that are distributed in Japan and partially in China and on the Korean Peninsula, are included in its composition (Anostirus daimio Lew., Ectinus candezi Lew., Ampedus optabilis Lew., Melanotus legatus Cand., Miwacrepidius subcyaneus Lew., Athous prenobilis Lew., Mucromorphus montanus Miwa., and some others). They are not encountered beyond the boundaries of Kunashir, and are concentrated mainly in the southern third of the island.

The overwhelming majority of the clickbeetles inhabiting the archipelago are associated with various types of forest vegetation, primarily with broadleaved-dark coniferous forests flourishing on the southern islands, and are represented by mesophilic species. They nearly all develop in rotten wood, under the bark of trees, or in soil under the forest canopy. Inhabitants of open spaces that are characteristic for the steppes or dry meadows, for example, representatives of the genus Agriotes Esch., are lacking in the Kuril elaterid fauna.

Selatosomus affinis Pk., which is very common in the meadows and alder stands of Paramushir, and Ectinusdahuricus Cand., which is very common in the mixed forest of the southern islands, are distinguished by somewhat elevated numbers. Some species are encountered sporadically (singly or in groups) on one or several islands, for example, Selatosomus reichardti Denisova, Cryptophypnus sp. 3, Ampedus sanguinolenthus Schrnk., A. optabilis Lew., A. pomorum Hbst., and Paracardiophorus pullatus Cand.

Of the clickbeetles found on the Kuril Islands, the following species are listed in the literature as pests of agricultural crops: Ectinus dahuricus Cand. on Sakhalin (Gusev, 1954), Selatosomus reichardti Denisova on Sakhalin and Japan (Gusev, 1954; Blunck, 1954), and Actenicerus pruinosus Motsch. in Japan (Blunck, 1954). These species do not inflict substantial damage on the Kuril Islands; this is explained by the small numbers and the lack of large areas occupied by agricultural lands. Ectinus dahuricus Cand., as the most numerous among the other species, may be regarded as a potential pest. It usually keeps to roads, meadows, and thinned out stands, and may even cause some damage to vegetable plantings in truck gardens at the present time.

The clickbeetle fauna of the Kuril archipelago is heterogeneous in origin. It is represented by Boreal and Palaearchaearctic complexes, divided into finer groupings in accordance with the ranges of particular species.

The Boreal complex consist of three groups, having a Holarctic, Transpalaearctic, and Beringian distribution. Just 2 species, Stenagostus undulatus Deg. and Ampedus nigrinus Hbst., are included in the Holarctic group. Seven species (Denticollislinearis L., Selatosomus impressus F., S. melancholicus F., S. affinis Pk., Sericus brunneus L., Ampedus sanguinolenthus Schrnk., and A. pomorum Hbst.) are included in the Transpalaearctic group. They have all been observed in the southern part of the archipelago, with the exception of Selatosomus affinis Pk., which is abundant in the north, and goes only as far as Iturup to the south, where it is found to be very rare. The Beringian group includes 2 species, Hypnoidus nocturnus Esch. and H.litoralis Esch. The first of these is distributed only in the north of the Range (Paramushir), on Kamchatka, the Aleutian Islands, in Alaska, Canada, and the northern USA; the second has a wider distribution; it is encountered on nearly all the large Kuril Islands, the Aleutian Islands, and in Alaska; it is known in Primorskiy Kray, and, it would seem, should be on Kamchatka as well.

The Palaearchaearctic complex, represented by Manchurian and Island species, is much richer and more diverse. In the Manchurian group we distinguish species that are fairly widely distributed on the continent, that have invaded the Kuril Islands, but which are lacking in Japan (Selatosomus ecarinatus Step., Ectinus piloselloides Schw., Ampedus nigror Rtt., and A. latiusculus Rtt.) and species which are also encountered in Japan (Actenicerus pruinosus Motsch., Selatosomus reichardti Denisova, Ectinus dahuricus Cand., Melanotus legatus Cand., Cardiophorus vulgaris Motsch., and Paracardiophorus pullatus Cand.). The ranges of these species reflect various stages of ancient links that existed in the geological past between the islands of East Asia and the continent.

The Island group may be regarded as a group of island endemics in the broad sense, since it combines species living on Sakhalin, Japan, and the Kuril Islands, but which are absent on the continent or are observed only on the Korean Peninsula. Depending upon the character of the distribution within the limits of the islands, this group is divided into three subgroups: the Kuril-Japanese (13 species), the Sakhalin-Kuril-Japanese (4 species), and the Kuril proper (4 species). Among the Kuril clickbeetles, the Island group constitutes the main nucleus of the fauna, since it includes about half of all the species. Many of the seven unidentified species will probably turn out to be Island species, which will further strengthen the dominant role of this group.

Some of the species of the Kuril-Japanese subgroup (Miwacrepidius subcyaneus Lew., Mucromorphus montanus Miwa, Anostirus daimio Lew., Selatosomus notabilis Cand., Ectinus sericeus Cand., Silesis musculus Cand., Ampedus optabilis Lew., and A. azurescens Cand.), as they have a patently Japanese origin, invade the Southern Kurils only in the northern part of their range (Kunashir, Shikotan), and in particular cases, the Korean Peninsula. On Kunashir these species are concentrated in the southern part of the island, mainly in the region of the caldera of Golovnin Volcano, at sites where thermophilic plants flourish. But even they are scanty or rare here. Another part (Actenicerus selectus Cand., Cryptophypnus difficilis Lew., Hypnocoelus japonicus Fleut., Dolopius exilis Kishii., and Ectinus candezi Lew.) go approximately as far as Iturup to the north, but are absent on Sakhalin. Of these species, the first three are known only on the Southern Kuril Islands and Hokkaido.

The Sakhalin-Kuril-Japanese subgroup combines species whose range encompasses the southern part of Sakhalin, the Southern Kurils, and the Japanese islands. These include Harminiussingularis Lew., Athous inornatus Lew., Selatosomus mundulus Lew., and Dolopius exilis Fleut. Athousinornatus Lew., which is not distributed in Japan beyond the boundaries of Hokkaido, is distinguished among these. This species in essence belongs to the scanty but highly characteristic Sakhalin-Kuril-Hokkaido subgroup.

The Kuril proper subgroup is made up of species described on the Kuril Islands and not found at other sites: Hypnoidus kurilensis Gur., Ampedus etorupenis Miwa, A. doli Miwa, and A. shakotanensis Miwa. All of these are extremely rare, were described on the basis of one find, and have not been encountered again. Some of these, possibly, will turn out to be true Kuril endemics; others may be found on adjacent territories (Hokkaido and Sakhalin); it cannot be excluded that some will be consolidated in a synonym, as has already occurred with other species. But thus far we regard them as Kuril endemics.

In connection with the fact that we have already published the collected material (find sites and number of specimens) (Gur'eva and Krivolutskaya, 1968), as well as to save space, we present the list of all the clickbeetle species known on the Kuril archipelago in Table 7.