Rare spider species (Araneae) of protected steppe areas of the Kharkiv Region (Ukraine)

Europe, and Russocampus polchaninovae in four localities. Northern boundaries of the geographic ranges of Civizelotes pygmaeus , Gnaphosa dolosa , Xysticus marmoratus, X. mongolicus , and the southern boundary of Gnaphosa lugubris run through the Kharkiv Region. On the edges of their areas, these species become habitat specialists and occur only in steppes and/or dry meadows. Xyticus mongolicus inhabits sandy and chalky steppes with sparse vegetation. Gnaphosa taurica has high ecological plasticity in the steppe zone, while in the forest-steppe, it is limited with chalk and limestone outcrops. Some species like Gnaphosa lugubris , G. licenti , G. taurica , Zora pardalis and Eresus kollari, were abundant in our samplings while 19 species were found as singletons. G. taurica , and E. kollari preferred chalky slopes, G. licenti both chalky slopes and top of a southern ungrazed slope, G. lugubris dominated on all slopes in the Velykoburlutskyi Steppe, while Z. pardalis was the most abundant in ungrazed gully bottoms in both Parks. Being not numerous, Altella hungarica , Euryopis laeta, Civizelotes pygmaeus and Drassyllus vinealis occurred annually in the same habitats that may indicate stability of their populations. Given their habitat specificity, even numerous species became vulnerable under the threat of anthropogenic transformation of natural ecosystems. The only way to protect them is to preserve their habitats .


Introduction
To date, the list of spiders of the Kharkiv Region accounts for 426 species. The material was collected in 78 localities, including seven conservation areas (Polchaninova, Prokopenko, 2017, 2019. The largest steppe habitats in the Kharkiv Region are protected in the National Nature Park (NNP) "Dvorichanskyi" and in the Regional Landscape Park (RLP) "Velykoburlutskyi Steppe". Arachnological research in the Velykoburlutskyi steppe was launched in 2003. Since that time, 183 spider species have been recorded, and an ecological study of the spiders of pasture ecosystems has been conducted (Polchaninova et al., 2016). The vicinity of Dvorichna has been under investigation since 2008, prior to the Park establishment. Currently, 147 spider species are known from this territory.
In the course of our study, a bulk of rare spider species has been recorded from the Parks; three species are listed in the Red Data Book of Kharkiv Region (Red Data Book…, 2013). The aim of the present paper is to summarize obtained data and to make a list of threatened species.

Material and methods
The studied Parks are located in the east of the Kharkiv Region, in Dvorichna and Velykyi Burluk districts. The NNP "Dvorichanskyi" hosts a variety of dry grasslands on the chalky slopes, the RLP "Velykoburluthskyi Steppe" presents a net of gullies covered with steppe and meadow vegetation. Spiders were collected in steppe habitats, on mesic floodplain meadows and on the forest edges.

Series "Biology", issue 32, 2019
General habitat characteristics is based on the species distribution in the steppe and forest-steppe zones of the East European Plain (Plochaninova, Prokopenko, 2013;Ponomarev, 2017). Names of geographic areas are adopted from Gorodkov, 1984and Kryzhanovsky, 2002, and explained in Polchaninova, Prokopenko, 2013.

Results and discussion
At present, 233 spider species have been registered in the NNP Dvorichanskyi and RLP Velykoburlutskyi Steppe. Of these, 32 species can assigned to the category of rare in the Kharkiv Region. Despite the fact that the investigated Parks are located in a distance of 40 km and host similar habitats, the long-term studies revealed only eight common species in this list. Eleven species were recorded form the Drorichanskyi Park and 13 species form the Velykoburlutskyi Steppe. This suggests the restrictions of species distribution and their vulnerability thus highlighting value of the Parks' territories for biodiversity conservation.
The most valuable are the finds of species with narrow ranges and patchy distribution: Russocampus polchaninovae has been found in Europe in four localities and Altella hungarica in seven localities only. The second is a group of species with wider European ranges but found in Ukraine in one (Lathys heterophthalma, Euryopis laeta), two (Trachyzelotes lyonetti, Pardosa maisa, Laseola coracina) or three (Talavera aperta) localities. The other species are rare or distributed locally in the Kharkiv Region.
Northern boundaries of the geographic ranges of Civizelotes pygmaeus, Gnaphosa dolosa, Xysticus marmoratus, X. mongolicus and the southern boundary of Gnaphosa lugubris run through the Kharkiv Region. The species existing at the border of their ranges often become habitat specialists. For instance, in the Kharkiv Region, Xysticus mongolicus inhabits only sandy and/or chalky steppes, and Gnaphosa taurica only chalk and limestone outcrops. In main areas of their ranges, both species possess high ecological plasticity.
Gnaphosa lugubris dominated annually all the steppe slopes in the Velykoburlutskyi Steppe being subdominant in the bottoms. In the Dvorichanskyi Park, this species was not abundant and preferred gully bottom. Gnaphosa taurica, in the contrast, occupied the slopes and peaked in number on the bare chalk. Such a habitat distribution of both species at the edge of their geographic ranges is stipulated by the differences in their geographical patterns, northern for the former species and southern for the latter.
Gnaphosa licenti was the most abundant on the ungrazed south-facing slope in the Velykoburlutskyi steppe as well as on the chalky slope in the Dvorichanskyi Park. Eresus kollari preferred chalky slopes being extremely abundant in certain years. Zora pardalis occurred mainly in gully bottoms; if on the slopes, it chose wetter conditions of the northern exposition or dense vegetation. Ozyptila pullata was a chalky slope specialist. Being not numerous, Altella hungarica, Euryopis laeta, Civizelotes pygmaeus and Drassyllus vinealis occurred annually in the same habitats that may indicate stability of their populations.
Inhabiting isolated localities, even numerous species become extremely vulnerable under the threat of habitat loss. The only way to protect them is to prevent anthropogenic transformation of their natural biotops, namely afforestation of steppe slopes, ploughing, and/or quarrying.