ACTA BOT. CROAT. 77 (2), 2018 193 Acta Bot. Croat. 77 (2), 193–196, 2018 CODEN: ABCRA 25 DOI: 10.2478/botcro-2018-0008 ISSN 0365-0588 eISSN 1847-8476 Short communication Galium divaricatum Pourr. ex Lam. (Rubiaceae) – a new species for the flora of Ukraine Pavel Novák1*, Dominik Zukal1 1 Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, CZ 611-37 Brno, Czech Republic Abstract – Galium divaricatum Pourr. ex Lam. is an annual plant species occurring mainly in dry grasslands. The centre of its distribution range is situated in the Mediterranean region, while in Central Europe it has been known only from a few isolated sites in Slovakia and Hungary. In 2016 we discovered this species in open dry grassland of the class Sedo-Scleranthetea on the upper edge of a basaltic andesite quarry near the village of Siltse, Irshavskyi Dis- trict, Zakarpatska Region, as a new species for the Ukrainian flora. The site is situated in the transitional region be- tween the Pannonian Basin and the Eastern Carpathians. The new locality represents the northernmost recent occur- rence of this species. Keywords: Carpathians, Mediterranean floral element, Pannonian Basin, phytogeography, Sedo-Scleranthetea, Zakarpatska Region * Corresponding author, e-mail: pavenow@seznam.cz Introduction Galium divaricatum Pourr. ex Lam. is a member of the Galium parisiense group, which contains annual species of open dry habitats. Besides G. divaricatum, two other spe- cies of this group occur in Central Europe, G. parisiense and G. tenuissimum. All three of these species are sparsely dis- tributed and occur mainly in the Pannonian Basin and in the warm foothills of the Carpathians (Paucă 1961, Řehořek 2007, Bartha et al. 2015). Of this group, only G. tenuissimum has been known in Ukraine (Mosyakin and Fedoronchuk 1999), where it is limited to Crimea (Yena 2012). This paper focuses on G. divaricatum which was discovered in the Za- karpatska Region (W Ukraine) as a new plant for the Ukrai- nian flora in June 2016. Galium divaricatum was described in France and is con- sidered to be a Mediterranean element of the European flora. The centre of its distribution range is in the Near East and Southern Europe. It is distributed in the Eastern Mediter- ranean Basin including Lebanon, Syria, Turkey and Cyprus and in the whole of the Balkan (e.g. Paucă 1961, Ehrendor- fer and Schönbeck-Temesy 1982) and Italian (Pignatti 1982) peninsulas. It is also known in southern France (Royer and Tison 2014). The westernmost localities of its distribution range are located in the Iberian Peninsula (Ortega Olivencia and Devesa 2007). G. divaricatum is also reported as a neo- phyte in various regions of the world (Lipscomb and Nesom 2007). There are several records of G. divaricatum in Cen- tral Europe (Fig. 1). It is known only in the south-eastern Fig. 1. Distribution map of Galium divaricatum in Central Europe based on literature records (circles) and the new finding in Ukraine (asterisk). NOVÁK P., ZUKAL D. 194 ACTA BOT. CROAT. 77 (2), 2018 part of this region. Its northern distribution limit has been assumed to occur in southern Slovakia (Řehořek 2007) and western Hungary (Bartha et al. 2015). There are historical records from volcanic bedrock at the southern edge of the Western Carpathians in Slovakia. It has been reported there in five sites near the villages of Blhovce, Fiľakovské Kováče, Plášťovce, Šiatorská Bukovinka and Tešmák (Řehořek 2007). The second site represents its northernmost occurrence in its native distribution range (48°17' N). However, it is currently supposed to be an extinct species of the Slovak flora (Eliáš et al. 2015). There are also several localities mentioned in Ro- manian Transylvania (Paucă 1961, Pop and Hodişan 1964). Nevertheless, it has not been known in Ukraine until now (cf. Mosyakin and Fedoronchuk 1999), when it was found in the western part of the country (Zakarpatska Region). The Zakarpatska Region has been investigated by botanists for more than one hundred years. However, their research (e.g. Thaisz 1911, Stojko et al. 1982) has focused mainly on the higher altitudes of this area and on a few sites with ther- mophilous vegetation in the volcanic Carpathian foothills (Fodor 1974, Votkalchuk 2012). In contrast, the flora of the flat lowland part of the region and the lower volcanic hills has not been sufficiently studied, as is reflected by several re- cent findings of new vascular plant species in this area (e.g. Felbaba-Klushyna 2015). G. divaricatum prefers open nutrient-poor dry grassland vegetation developed on substrates of various pH (Paucă 1961, Royer and Tison 2014). To our knowledge, the on- ly phytosociological relevé with G. divaricatum recorded in Central Europe was published in the above mentioned pa- per from Romanian Transylvania (Pop and Hodişan 1964). It occurs there in dry grassland dominated by Festuca valesi- aca with the occurrence of several annual species indicating disturbance. This grassland probably belongs to the alliance Festucion valesiaceae Klika 1931. The aim of this study is to report the occurrence of G. di- varicatum in Ukraine, to describe the new site and to put this finding into a broader phytogeographical context. Materials and methods The Zakarpatska Region is located in the transitional zone between the Pannonian and Carpathian biogeographi- cal regions (Fekete et al. 2016) which makes its position quite unusual for Ukraine. Its low-altitudinal south-western part, including the locality of G. divaricatum, belongs to the dis- tinctive Pannonian Province of the forest-steppe geobotani- cal zone (Didukh and Shelyag-Sosonko 2007). The mean an- nual temperature of the surroundings of the G. divaricatum site is around 9 °C and annual precipitation is around 800 mm (Andó 1999). The climate supports the development of forest vegetation on zonal sites with deep soils on flysch or loess. Therefore, remnants of dry grasslands are limited to small patches with shallow dry soils situated on sunny slopes of the volcanic hills that are scattered in the lower part of the region (Fodor 1974). G. divaricatum was determined using identification lit- erature (e.g. Paucă 1961, Ehrendorfer and Schönbeck-Teme- sy 1982, Royer and Tison 2014) and herbarium vouchers stored in the Herbarium of Masaryk University, Brno, Czech Republic (BRNU). The determination was confirmed by an expert in the G. parisiense group Vladimír Řehořek (Ma- saryk University, Brno). The herbarium specimens of G. di- varicatum from the new site have been deposited in BRNU. The nomenclature of plants in the article follows Euro+Med PlantBase (2006–). Fig. 2. Galium divaricatum (left) and its site in a basaltic andesite quarry (right) above the village of Siltse near Irshava taken from the south. The place in which the species occurs is indicated by an arrow (photo P. Novák, 10 June 2016). GALIUM DIVARICATUM IN UKRAINE ACTA BOT. CROAT. 77 (2), 2018 195 Results and discussion During phytosociological research into dry grassland vegetation near the village of Siltse (Irshavskyi District) on 10 June 2016, we discovered several dozen individuals of an annual plant species belonging to the Galium parisiense group. It was subsequently recognised as G. divaricatum, a new species for the Ukrainian flora (cf. Mosyakin and Fe- doronchuk 1999). The new locality of G. divaricatum is a basaltic andesite quarry on a south-facing slope of a hill above the village of Siltse (Fig. 2). The hill is part of the Vihorlat–Gutâi Volcanic Belt (Andó 1999). G. divaricatum grows on the upper edge of the quarry near a footpath to the hilltop (48°17'36.1" N, 22°59'17.6" E) at an altitude of 200 m. It was recorded in open grassland containing mainly thermophilous acidotol- erant therophytes such as Anthemis arvensis, Arenaria ser- pyllifolia, Bromus hordeaceus, Filago arvensis, Polycnemum arvense, Scleranthus annuus and Vulpia myuros. Some pe- rennial species occurred there as well, e.g. Centaurea stoe- be, Chondrilla juncea and Rubus sp. This temporary pioneer vegetation type may be classified within the class Sedo-Scler- anthetea Br.-Bl. 1955. Remnants of dry grasslands dominat- ed by Festuca valesiaca s.l. (class Festuco-Brometea Br.-Bl. et Tüxen ex Soó 1947) were developed on the hilltop above the quarry. However, G. divaricatum was not found in this veg- etation. The soil pH of the rocky dry grassland near the site with G. divaricatum was 5.6 (measured in a distilled water suspension). The flora of the region contains many thermophilous species of both subcontinental (e.g. Koeleria glauca and Sti- pa pulcherrima) and sub-Mediterranean (e.g. Fraxinus or- nus, Quercus cerris, Q. pubescens, Ventenata dubia) floral elements. The co-occurrence of these elements is highly characteristic for the region (Fodor 1974) as well as for the whole of the Pannonian Basin (Fekete et al. 2016). There- fore, the new occurrence of G. divaricatum fits well into the character of the regional flora. Since the species is consid- ered extinct in Slovakia (Eliáš et al. 2015), the newly discov- ered site in Ukraine represents the northernmost outpost of its current occurrence. The origin of this newly discovered population is unclear. It cannot be ruled out that it was brought to the site by hu- man activities; this hypothesis is supported by the fact that the species was not observed in the surrounding dry grass- land vegetation during our field survey. Nevertheless, it is considered to be a native species both in Hungary (Bartha et al. 2015) and Slovakia (Řehořek 2007). If the native status of the new population is confirmed, it should be classified as a critically endangered species (CR) of the Ukrainian flo- ra with the application of criteria B1a + B2ab (iii, v) of the IUCN standards (2016). Acknowledgements We would like to thank Vladimír Řehořek who kindly re- vised the herbarium specimen of Galium divaricatum from Ukraine, Kryštof Chytrý and Kateřina Píšťková for taking care of the field herbarium, Martin Večeřa for preparing the distribution map, Lubov Borsukiewicz and Iveta Škodová for providing some regional literature and Milan Chytrý and Ve- ronika Kalníková for valuable comments on the manuscript. 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