Biosystems Diversity Biodiversity of Sciaridae (Diptera) in Ukraine

Sciarids Sciaridae) or black fungus gnats are small, mainly dark coloured insects whose larvae usually devel- op in rotting plant remains permeated by fungal hyphae. Typical habitats for sciarids are shaded forests and wet meadows, but some species can migrate from natural biotopes to anthropogenic ecosystems and live as synanthropes. We have inves- tigated ecological and chorological features of sciarids in Ukraine since 2012. Within this work, we collected imagoes during expeditions and excursions in different biotopes using the Malaise trap, by the method of sweeping and with ex- hauster directly from substrate. Collected imagoes were placed into 5 mL vials with 70% ethanol. In the lab fixed material was dehydrated in absolute ethanol and mounted on the slides in Euparal. Previous registrations are based on 6 field collec- tions, two of them were carried out in the XIX century, 4 observations of “army worms” and two pest records. From published material of these collections 78 sciarid species were known from 17 genera in 8 more or less specified localities of Ukraine. Our sciarid study in the country expanded the data on registered sciarids by adding 18 new species and enriched information about the distribution of sciarids by 86 new findings of previously known species in 12 regions (Volyn, Cher- kasy, Chernihiv, Ivano-Frankivsk, Kharkiv, Khmelnytsk, Kyiv, Lviv, Odesa, Poltava, Rivne and Ternopil) of Ukraine. The current checklist of Sciaridae of Ukraine contains 96 species from 17 genera in 168 localities. Through comparison with Germany, whose sciarid fauna is studied much better, for Ukraine we can predict the presence approximately 400 sciarid species, so the species diversity of Sciaridae in Ukraine still poorly known for the known species does not exceed 25 per- cent of presumed existing species here. The majority of sciarid findings are registered in different types of broadleaf forest biotopes, only a few species have been found also in grassland habitats. Some sciarid species show synanthropic attraction and have been registered in anthropogenic habitats, for example Bradysia fenestralis (pest of cultivated plants in greenhous-es), Corynoptera dentiforceps , Scatopsciara atomaria and Corynoptera tridentata . Larvae of Bradysia placida develop in rotten wood, also development of Corynoptera membranigera preimaginal phases possibly takes place in the fruit bodies of fungi ( Neoboletus luridiformis , Russula sp.) and Mycetozoa ( Fuligo septica ).


Introduction
Black fungus gnats or sciarids are small (length of imago up to 8 mm), mainly dark coloured insects from the Sciaridae Billberg, 1820 family (Diptera). Sciarid larvae usually develop in rotting plant remains permeated by fungal hyphae. Typical habitats for sciarids are shaded forests and wet meadows, but some species can migrate from the natural biotopes to anthropogenic ecosystems and live as synanthropes (Broadley et al., 2018). The world fauna includes more than 2,200 sciarid species from 83 genera (Roscov et al., 2017).  published the latest Palearctic sciarid fauna revision in 2000 and listed there 836 sciarid species from 28 genera. In Europe 32 genera and 673 sciarid species are registered (Menzel & Heller, 2013).
The comprehensive faunistic research on sciarids in Ukraine has not been carried out before (www.catalogueoflife.org). These gnats were only studied in: 1930s -by Bukowski andLengersdorf in Crimea, 1960s -by Mamaev with Krivosheina and1990s -by Dmitrieva in Transcarpathia (Zakarpatska Region) (Bukowski & Lengersdorf, 1936;. From the other regions of Ukraine only a few sciarid findings were known before: five species were registered in Lviv Region by Nowicki, three species were first described from Podolia by Winnertz and per one species was known from Ivano-Frankivsk Re-gion, the western regions, excluding the Carpathians by Osmola and Odesa Region by Nepomyashcha and Uzhevska (Verkhratskyi, 1864;Nowicki, 1864Nowicki, , 1865Winnertz, 1868;Osmola, 1970;Nepomyashcha & Uzhevska, 2010). In total, according to the literature, 17 genera and 78 sciarid species were recorded in our country.
There are many natural biotopes with convenient conditions for sciarid development in Ukraine. First of all, one should note the forest ecosystems, located in the Forest and the Forest-Steppe zones which cover ca. 55% of Ukrainian territory. Moreover, the primeval beech forests of the Ukrainian Carpathians and the ancient oak forests of Polissya are especially promising as natural refugia where endemic and relict Sciaridae probably survive. Also, wet meadows and coastal ecosystems of Ukraine are very interesting as sciarid natural habitats and need to be studied in the framework of sciarid biodiversity research.
In comparison with the well-known sciarid fauna of Germany the species list of Sciaridae registered in Ukraine is remarkably poor. As of 1999 in Germany 342 sciarid species were recorded, but in Ukraine only 78 species were known (Menzel, 1999). Given that the area of Ukraine exceeds the area of Germany almost by 246 000 km 2 and our country is characterized by not worse conditions for sciarids' development, we can expect that the biodiversity richness of Sciaridae in Ukraine will be at least not poorer than in Germany and we can predict the presence up to 400 sciarid species in our country. Thus, it can be concluded that only up to 25% of the species diversity of Sciaridae in Ukraine was known and, of course, needed further research.

Materials and methods
Material was collected during expeditions and excursions from 2013 to 2018 in different forest, meadow and coastal natural habitats and in anthropogenic biotopes of Ukraine. Adult males were collected by the Malaise trap, sweeping with entomological nets and with aspirator directly from a substrate. Collected gnats were kept in 5 mL vials with 70% ethanol. In the laboratory, males were dehydrated in absolute ethanol and mounted on slides in Euparal.
The morphology was studied with MBS-9 and Biolam D11 microscopes equipped with Nikon D90 camera; images processed using NKRemote Version 2.2.1, AxioVision Version 4.6.3 and Photoshop CC 2018 programs; pictures stacked by Helicon Focus 6.7.1 open source software. A map was created using QGIS (version 3.10.10). All of the studied material is kept in Andriy Babytskiy's Private Collection, Kyiv (PABK) and deposited to the public on the Ukrainian Biodiversity Information Network (Babytskiy, A. (2018) The nomenclature and systematics follow the revision of Palaearctic Sciaridae  and Revision of the Black Fungus Gnats (Diptera: Sciaridae) of North America (Mohrig et al., 2013) with consideration of separate genera revisions Vilkamaa & Menzel, 2019).

Results
Since 2012, we have studied the ecological and chorological peculiarities of sciarids in Ukraine. By now, we have accumulated data on the Ukrainian sciarid fauna, previously known sciarid species' localities in our country and supplemented the species list with our own findings. The list of new findings of sciarids in Ukraine is given below.
Other species we collected in the ecotone habitats, as S. (S.) calamophila (coastal willow synusia), C. inundata and P. (P.) brunnea (hanging swamp on the travertine in broadleaf forest). Only in the grassland habitat we collected S. (S.) pusilla (swampy valley of Desna River).
For another species group a slightly wider environmental valence was inherent and they were registered in different types of habitats. Bradysia placida was registered in the different broadleaf forests (hornbeam, alderoak and birch), but also, we collected it on the meadow, hanging swamp, sandy beach and bank of a lagoon. In addition, this species occurred in the countryside near a house. Corynoptera membranigera was indicated in hornbeam, oak, birch, maple-robinia and broadleaved-coniferous forests and in the forestry meadow where its imagoes tend to inhabit wet areas such as ravines, tall or dense grasses, and be distributed on hortobium (grass level), dendrobium (trees and shrubs level) and herpetobium (leaves litter, fungal fruit bodies and rotten wood level), where their larvae evidently develop. Some specimens of C. membranigera male imago were collected on the fungus (N. luridiformis, Russula sp.) and Mycetozoa (F. septica) fruit bodies, which can imply possible existence of trophic links between C. membranigera larvae and specified organisms . Corynoptera tridentata was registered in oak forest, on a meadow and in an anthropogenic vegetable garden, S. (S.) atomaria was collected in birch-hornbeam, alder forests and countryside, S. hemerobioides -in the hornbeam-oak, beech forests and meadowy grassland near a road, Z. (Z.) sciarina -in beech forest and on the bank of a lake, overgrown by willow trees.
Some sciarid species showed synanthropic attraction and have been registered in anthropogenic habitats. One of them was B. fenestralis, which we found only on the windowsill of the university campus. This sciarid was previously recorded as a tomato and cucumber pest, also it was found in a greenhouse with decorative plants in the Altay and in a vegetable store in Kazakhstan (Gerbachevskaja, 1963Sataeva, 2006). C. dentiforceps and S. (S.) atomaria were found in the countryside near the rotten remains of a branch of a walnut tree, which may indicate trophic links of their larvae with rotten wood. From rotten wood, collected in the countryside, male imagoes of B. placida were bred from the larvae. Also C. tridentata was collected in a vegetable garden.
In general, we can conclude that registered sciarids are mostly forest species, but can develop in grassland biotopes with sufficient moisture level and plant remains.

Discussion
According to the results of literature analysis and our research, the current list of sciarids recorded in Ukraine contains 96 species from 17 genera. All previously recorded species and our findings with confirmed identification are listed below. It should be noted that the list contains only previously published data and findings given in this article. Information about found but unpublished sciarid species and unverified material is not included in the list. Approximately, we expect the presence of about 400 sciarid species in the fauna of Ukraine.
Findings of the species known from the literature and our findings that have been published before are provided with appropriate citations, published findings in this article are provided with the numbers of the specimens in the PABK. The number of registered sciarid species in the different regions of Ukraine is shown in the map (Fig. 1).  (Winnertz, 1867). Localities: Crimea [as B. morio (Fabr., 1794]), Zakarpatska Region (Krivosheina & Mohrig, 1986 [as B. mutabilis (Lengersdorf, 1926)]). Mohrig & Krivosheina, 1989. Localities: Volyn Reg. .