KEROPLATIDAE, MYCETOPHILIDAE) IN THE KOSTOMUKSHA STATE NATURE RESERVE, RUSSIA

Fungus gnats represent an informal assemblage of insect families in the superfamily Sciaroidea. This is a highly diverse group comprising nearly 1000 species in Fennoscandia. Fungus gnats are comparatively well studied in the Republic of Karelia, although the coverage is uneven. Hence, any new data from poorly known areas would provide a better background for further analysis of zoogeographical patterns both at local and at Fennoscandian level. With just 100 known species, the fauna of fungus gnats in the Kostomuksha State Nature Reserve has until recently been insufficiently studied. The paper presents the results of faunistic research in the Kostomuksha State Nature Reserve since 1993. The revised checklist is based on original material and includes 177 species of fungus gnats belonging to the families Bolitophilidae, Diadocidiidae, Keroplatidae and Mycetophilidae. Eighty-five species were added to the fauna, and eight species were removed from the list. The revealed diversity is comparatively low and most of the recorded taxa are common in Fennoscandia. However, a number of rare and remarkable species was found, indicating a potentially rich fauna. Five species (Mycomya obliqua, Sciophila krysheni, Syntemna morosa, Mycetophila devioides, Mycetophila haruspica) are reported for the first time from the Republic of Karelia and Russia. Mycomya obliqua is also new for the Palaearctic region. All remarkable records are commented, and male genitalia images are provided for poorly known species. Two species of presumably western origin (Sciophila krysheni and Mycetophila devioides) and one Nearctic species (Mycomya obliqua) are discussed in more details. A relatively low diversity is explained by an insufficient earlier collecting activity and concentration of recent Malaise trapping on small islands with a poorer fauna. The need for further studies in the Kostomuksha State Nature Reserve, with a better coverage of habitats and using additional collecting methods, is substantiated.


Introduction
The informal name «fungus gnats» is used by most authors to designate an assemblage of five families in the superfamily Sciaroidea: Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae and Mycetophilidae. This is a highly diverse group, including more than 5000 species worldwide (Pape et al., 2011) and nearly 1500 species in the Palaearctic region (Søli et al., 2000). In Europe, the diversity of fungus gnats increases northwards, with the richest fauna in the boreal zone. Fungus gnats are well known in Scandinavian countries, largely due to growing interest since the beginning of the XXI century. Nowadays, the number of known species exceeds 750 in Finland and Sweden Jakovlev, 2014), and 600 (only for the family Mycetophilidae) in Norway (Søli & Rindal, 2012), and may reach around 1000 in the whole of Fennoscandia (Salmela & Kaunisto, 2015).
The Republic of Karelia (hereafter -Karelia), with 676 known species of fungus gnats , is one of the best-studied regions in Russia. However, with a few exceptions, collecting in its territory has been sporadic (Polevoi, 2000;Yakovlev et al., 2003), giving a rather fragmented picture of the fungus gnat distribution. This hampers the analysis of zoogeographical patterns at local and Fennoscandian level, and makes any new data from insufficiently studied areas very important. Kostomuksha State Nature Reserve is one of the places with a poorly known fauna of fungus gnats. The available species list, including 95 species, dates back to the late 1990s and is based on irregular sampling in several locations (Polevoi, 1997). Five species were added in previous publications (Polevoi, 2001a(Polevoi, , 2003Polevoi & Hedmark, 2004;Jakovlev & Polevoi, 2008). Besides, there are numerous recent, unpublished additions to the fauna, and the existing list needs taxonomic revision, too. Some of the published species were split into separate taxa, others are differently interpreted nowadays.
In this paper, we aimed to incorporate all available data from the Kostomuksha State Nature Reserve in a revised species list, provide additional information on poorly known species and briefly discuss the zoogeographic patterns observed in the local fauna.

Material and Methods
The Kostomuksha State Nature Reserve is located in the central part of Karelia, near the border with Finland. This area belongs to the northern taiga subzone and is mostly covered by coniferous forests. More information on ecosystems can be found in Lindholm et al. (1997).
Material was collected during several short expeditions in 1993-1995 and in 2012. Additional data were obtained in 2017 as a result of a Malaise trapping project. Twelve portable Malaise traps were installed on islands in Lake Kamennoe and in the forests along its shores. The traps were deployed on 12-14.06.2017 and checked twice a month until 05-06.09.2017, when all the traps were removed. Collecting points were grouped into seven localities ( Table), and Malaise trap sites were assigned to the nearest named locality (Fig. 1). Details on collecting methods and habitats for each locality are given in Table. All the material is stored in the collection of the Forest Research Institute in Petrozavodsk (if not stated otherwise). The or-der of families and nomenclature in the species list follows .

Results
The fauna of the Kostomuksha State Nature Reserve includes 177 species of fungus gnats. Five species (Mycomya obliqua (Say, 1824), Sciophila krysheni Polevoi, 2001, Syntemna morosa Winnertz, 1863, Mycetophila devioides Bechev, 1988, Mycetophila haruspica Plassmann, 1990) are reported for the first time from Karelia and Russia. Mycomya obliqua is also new for the Palaearctic region. Additionally, six previously undescribed species will be considered elsewhere, and they are not included in the present list. Eighty-five species (marked with an asterisk) were added to the fauna of the Kostomuksha State Nature Reserve. Eight species, earlier published from this Protected Area, should be removed from the list. Additional comments are provided for species erroneously reported in previous publications and for rare species with poorly known distribution.

Discussion
Considering the relatively low number of species recorded, a detailed discussion on the zoogeographical structure of the fauna is hardly possible, but several aspects are worth mentioning. Most of the species found in the Kostomuksha State Nature Reserve are common and widely distributed, not only in Karelia or Fennoscandia, but also in the Palaearctic region as a whole. Due to the location of the study area in the northern taiga subzone and its proximity to the western border of Karelia, we could expect to find western and northern elements in the fauna. However, only Sciophila krysheni and Mycetophila devioides can be tentatively considered as a species of western origin, based on their known distribution. As to typical northern species, it appears that such taxa are mostly limited to the northern boreal, subarctic and arctic zones, dispersing southwards not farther than the northern flanks of spruce (Picea abies (L.) H.Karst.) forests. The record of Mycomya obliqua as a new species for the Palaearctic region is remarkable, but not something extraordinary. As our knowledge of the regional fauna increases, more and more Nearctic species are being found (Polevoi, 2010;Jakovlev et al., 2014;Salmela & Kaunisto, 2015;Polevoi & Salmela, 2016). It becomes clear that a substantial part of fungus gnats occurring in the northern boreal zone have a circumpolar range. Therefore, we can expect further findings of Nearctic species in the Palaearctic region and vice versa.
It is evident that the collecting activity in the Kostomuksha State Nature Reserve prior to 2017 was insufficient. The phenology in Sciaroidea is not uniform and certain species groups may be active in various periods during the flight season (Polevoi, 2000). So, a more or less complete coverage of the fauna can only be achieved through continuous sampling from early spring to late autumn. The Malaise trapping in 2017 satisfied these requirements and produced quite a good catch, which almost doubled the number of known species. Still, 177 species is a relatively small number of taxa, compared with other local faunas in Fennoscandia. For example, 277 to 320 species were reported from several localities in Norway (Økland & Zaitzev, 1997;Kjaerandsen & Jordal, 2007;Søli & Rindal, 2012); 248 species were found in the Tyresta National Park in Sweden ; and 310 species -in the Koitajoki Protected Area in Finland (Polevoi, 2001b). In the Pasvik State Nature Reserve (Murmansk region, Russia), 329 species were detected during just two years (Polevoi, 2010). Such an unexpectedly low diversity can be explained by the placement of most Malaise traps on small islands, where the fauna may be considerably poorer.

Conclusions
We can definitely state that the fungus gnat fauna of the Kostomuksha State Nature Reserve is far from being comprehensively studied. On the other hand, a range of remarkable records and the finding of previously undescribed species may indicate a potentially high diversity of fungus gnats in this area. More studies are needed, which should not only cover the whole flight activity period, but also include various habitats. Although Malaise traps appear to be one of the best methods for catching fungus gnats, there are other approaches (window traps, sweet bait traps, pitfall traps and colour plates, emergence traps) which probably should be used, too.