NEW RECORDS AND DISTRIBUTION OF SPECIES FROM GENUS ARCTOPHILA SCHINER, 1860 (DIPTERA: SYRPHIDAE: ERISTALINAE) IN SERBIA

The genus Arctophila comprises large, bumblebee-like species of hoverflies (Diptera: Syrphidae). In Europe occur three species from this genus: A. bequaerti, A. bombiforme and A. superbiens and all of them were recorded in Serbia. Species from this genus were registered only on few mountains in Serbia and are considered rare in the country. During a survey conducted in 2018 and 2019, all three species were registered at several localities. The new findings of these species, photographs, maps of distribution and flight period diagram are presented in this paper. The descriptions of localities and observations related to the ecology of the species are also presented.


INTRODUCTION
Hoverflies (Syrphidae) are one of the most species-rich families of Diptera, with over 6000 described species belonging to 188 genera (THOMPSON, 2013). In Europe occur about 870 species, while the hoverfly fauna list in Serbia contains 412 species (SPEIGHT, 2016;. This family is widespread in the world and is an ecologically important group of insects that perform ecosystem services, like plant pollination, predation of plant pests and nutrient recycling (ROTHERAY and GILBERT, 2011).
Genus Arctophila Schiner, 1860 contains large robust bumblebee-mimic flies with long hairs on thorax and abdomen. The wing contains characteristic wedge-shaped dark spot in the middle, arista is feathered with long hairs and face is extended downwards so it forms a conical snout. Species from this genus may be confused with other bumblebee-like syrphids like Pocota Le Peletier & Serville, 1828 and Criorhina Meigen, 1822 (though they have bare arista) or Volucella Geoffroy, 1762 (with closed R1 vein on the wing) ( VAN VEEN, 2004

MATERIAL AND METHODS
Field surveys were conducted during 2018 and 2019 at several localities in Serbia (Table  1.). Specimens were observed and caught by the entomological net and prepared by standard procedure. The identification of specimens was based on morphological characters and performed with the use of key SPEIGHT and SARTHOU (2017). The exact coordinates and altitudes were recorded on the spot using GPS devices, and all the data were systematized in our database Alciphron (http://alciphron.habiprot.org.rs/), after field surveys. The maps of distribution were made using QGIS 2.18 (www.qgis.org). The collected material is deposited in the private collection of the first author and at the Department of Biology and Ecology, University of Novi Sad (FSUNS).

Description of localities
Đerekare is a place in the western part of Serbia, between Pešter plateau and the border with Montenegro. Dominant forests are of beech (Fagus sp.), spruce (Picea abies (L.) H.Karst.), silver fir (Abies alba Mill.) with some mountainous grasslands. Quite a lot of cattle can be found in the area, especially cows.
Locality Bijela Voda is montane grassland, close to a beech-evergreen forest and with abundant livestock. The most numerous plants are Poaceae, Veratrum sp., Gentiana lutea L. and Parnassia palustris L.
Locality Stari Krst is situated next to the road, in the spruce-silver fir forest. A stream is flowing nearby, and dominant plants are Vaccinium myrtillus L., Rubus idaeus L., Sambucus racemosa L. and Cirsium sp.
Jadovnik is a mountain in the southwestern part of Serbia, on the western edge of Pešter plateau, close to the town of Prijepolje. On mountain slopes dominant are forests of beech, spruce and fir, while higher parts are covered with meadows and pastures with shrubs of Juniperus communis L., Rubus idaeus L., Ribes sp. and Chamaecytisus sp. (MARKOVIĆ, 1990). In many places was evident intensive logging that can destroy pristine habitats and endanger the survival of lignicolous organisms.
Locality Mali Jadovnik is subalpine grassland surrounded by evergreen forests with dominant plants of the Asteraceae family (Cirsium sp., Centaurea sp., Carduus sp) and shrubs of Juniperus communis L.and Rubus idaeus L.
The plateau of Vlasina is in the southeastern Serbia, close to the border of Bulgaria. The lowest altitude at Vlasina is around 1200m a.s.l., making this area one of the widest and highest plateaus in the country. The area is surrounded by mountains that belong to the Rhodope Massif: Vardenik, Čemernik, Gramada (Plana) and Bukova Glava (STANKOVIĆ and LAUŠEVIĆ, 1997; RANĐELOVIĆ and ZLATKOVIĆ, 2010). Vlasina is a water-rich area with many small springs, streams and rivers. Extensive hydro technical interventions caused the formation of Vlasina Lake (BELIJ et al., 2014), located in the center of the area. Geology and water caused the forming of acid soils. This is a zone of dystric brown forest soil, which develops in mountainous regions within a beech forest zone but is nowadays mostly eroded and covered by grassy vegetation. Inside of this zone, eugley and dystric cambisol (swamp) soil types are also present (RANĐELOVIĆ and ZLATKOVIĆ, 2010). Zonal beech forests are very fragmented nowadays and have been replaced by dry grassland vegetation due to strong anthropogenic pressure in the past. Other major vegetation types include silver birch (Betula pendula Roth) forests, developing as a succession stage and hygrophilous vegetation communities along streams and the lake itself (RANĐELOVIĆ and ZLATKOVIĆ, 2010).
Localities Cvejina Dolina and Srednja Reka are situated in a valley between beech forests, near to the confluence of Plavilo river into Cvejina Reka river and along the course of the Srednja Reka river. In vicinity, dominant are beech forests, shrubs such as Rubus idaeus and Vaccinium myrtillus L., umbellifers, composites and Filipendula sp.
Locality Dejanova Reka is situated next to the road where beech forests and fragmented mires are present. Dominant are plants that prefer mires and wetlands: Succisa pratensis Moench, Epipactis palustris (L.) Crantz, Equisetum sp. and Salix sp.
Locality Gadžini is situated next to the road in the beech-birch forest. Present are numerous shrubs of Vaccinium myrtillus L.
Locality Jančin Potok is located next to the road, on the beech forest edge and dominant plants are Epilobium angustifolium L. and Rubus idaeus L.
Locality Jančini is situated next to the road, between Pinus sylvestris L. forest and beech-birch forest.
Locality Mali Čemernik is situated in the beech forest on Čemernik mountain. Present are little puddles and numerous rotten beech trunks.
Localities Plavilo 1 and Plavilo 2 are situated next to the Plavilo river on the Čemernik mountain. The river is surrounded by flooded meadows overgrown with Polygonum bistorta L., Filipendula sp., Potentilla sp., Valeriana officinalis L. and spruce forest. In the forest present are springs, puddles and semi-liquid mud that may be a habitat for larval development.
Locality Polom is a place in the beech-birch forest where concrete pipes were laid for transferring water from Polomska Reka river to Vlasina Lake accumulation. In this site a very pronounced anthropogenic influence is evident. 154 Locality Taraija is the edge of willow forest with a spring. In the surrounding area also present are forests of pine, spruce and birch.
Locality Teskovo is situated near Vlasina River, on the edge of a willow forest. The most numerous plants by the river are Mentha sp. and Scabiosa sp.
Locality Veliki Čemernik is situated on Čemernik mountain, along the course of a stream winding through coniferous forest. Quite a lot of cattle use it for pasture and water in stream is contaminated with cow feces. Stream shores are overgrown with Vaccinium myrtillus L., Chamaecytisus sp. and Polygonum bistorta L.
Locality Vlasina Rid is a settlement above Vlasina Lake. There are many private houses, few streams and beech-birch forests.

RESULTS AND DISCUSSION
Altogether 41 specimens of all three Arctophila species occuring in Serbia and Europe were collected -A. bequaerti, A. bombiforme and A. superbiens.  Notes: A. bombiforme is a species whose presence has long been known in Serbia (GLUMAC, 1955) and is widespread in Europe. The species is present in Scandinavia, mountainous parts of much of Europe, including Pyrenees, Apennines, the Alps, Balkan, mountain ranges in Spain, Crete and Turkey (SPEIGHT, 2015). In Serbia A. bombiforme was recorded on mountains Kopaonik, Šar planina, Zlatar and Jadovnik (RADENKOVIĆ, 2008;MILIČIĆ et al. 2018). At localities Jadovnik, Mali Jadovnik, Đerekare and Bijela Voda specimens were collected while feeding on Scabiosa sp. flowers in subalpine grasslands. On 156 locality Đerekare, Stari Krst adults were observed in copulation which lasted a few seconds during the flight, some two meters above the ground. At the same spot noted were specimens frequently fling around Vaccinium myrtillus L. shrubs next to the stream contaminated with cow feces. At localities on Vlasina plateau specimens were mostly spotted in wetlands, marshes, at forest edges and near streams and springs. The exception is Polom, where one specimen was collected while resting on the concrete pipe transfering water from Polomska Reka river to the Vlasina Lake accumulation. A. bombiforme was recorded together with A. bequaerti at localities Jančin potok, Plavilo 1, Plavilo 2 and Vlasina Rid. This species may be also present on Karamanica Mt. (42.353432 22.337244) (Fig. 1F) and Sopotnica (43.289428 19.744572) where bumblebee-like hoverflies were also observed at beech forest edges but were not caught. Adults were observed feeding on flowers: Succisa pratensis Moench (Fig. 2D), Scabiosa sp. (Fig. 2E), Gentiana asclepiadea L. and Cirsium sp.