Revision of occurrence and phytosociology of Ranunculus pedatus Waldst. et Kit. in Slovakia

: Ranunculus pedatus is a Eurasian species with a northern distribution edge in southern Slovakia. In the nineties of the 20 th century, it was assumed that the species probably occurs only near Štúrovo. Occurrence in the Hron and Ipeľ basins and several localities in the Podunajská nížina lowland between Komárno and Štúrovo was considered historical. Our research was conducted in the field and herbarium collections of 15 herbaria in Austria, the Czech Republic, Hungary, and Slovakia. Except for the well-known occurrence on salt habitats north of Štúrovo, we confirmed the recent occurrence of R. pedatus in Štúrovo town, around Chľaba village and in Ipeľ Basin (Pastovce, Tupá). The new, easternmost Slovak locality was found near the village of Koláre. Recently, 30% of all known sites were confirmed, so we propose reclassifying the species in Slovak Red List from the category critically endangered (CR) to the category endangered (EN). It occurs in salty meadows of the alliance Festucion pseudovinae (class Festuco-Puccinellietea ) and in mesic meadows of alliance Arrhenatherion elatioris and Deschampsion cespitosae (class Molinio - Arrhenatheretea ).


Introduction
Genus Ranunculus includes, in a broad sense, more than 300 species distributed worldwide except lowland tropics (Cook 1993;Tutin & Akeroyd 1993;Whittemore 1997). About 40 taxa are known in Slovakia (Futák 1982;Husák & Slavík 1982), and a half of them belong to relatively common taxa. Twenty-one species are included in the actual Slovak Red List of ferns and flowering plants, where Ranunculus pedatus ( Fig. 1) is evaluated in the category "critically endangered" (Eliáš et al. 2015). The species is a Eurasian perennial species, and its distribution extends from Slovakia, Hungary, Romania and Bulgaria, through the former Yugoslavia, Ukraine, southern and central Russia to Crimea, the Caucasus, Siberia and Turkey (Feráková 1999). From the taxonomical point of view, the species is included in subgen. Ranunculus and sect. Ranunculastrum (Tutin & Akeroyd 1993) or sect. Pterocarpa (Tzvelev 2012). Two subspecies are known to occur within the distribution area; subsp. pedatus is present in most of the area, whereas subsp. trojanus Davis is known in Turkey (Davis 1965 (Tzvelev 2012;Hörandl & von Raab-Straube 2015).
In Slovakia, R. pedatus is considered a halophytic species and occurring in the Festucion pseudovinae and Puccinellion limosae communities. According to current knowledge, the species occurs currently only in the vicinity of Štúrovo, in some areas (the Ipeľ Basin), it has not been found for a long time (Futák 1982;Feráková 1999).
Two aims of our work were: 1) to revise the historical and current occurrence of the species in Slovakia, and 2) based on our phytosociological relevés, to analyse the communities with the presence of R. pedatus.

Material and Methods
The study was carried out during [2017][2018][2019][2020]. The data concerning the distribution of the species was achieved from public herbaria BP, BRA, BRNM, BRNU, KO, LTM, MMI, NI, PMK, PR, PRC, SAV, SLO, W, and ZV. Abbreviations of herbaria are according to Thiers (2020+). Phytogeographical divisions of Futák (1980) are used. The map was prepared in Corel Draw using the map grid described by Niklfeld (1971).
We used only our published (relevés 2, 5, 8 in Tab. 1, Dítě et al. 2010) as well as unpublished phytosociological relevés. The phytosociological relevés were sampled according to the Zürich-Montpellier approach using the adapted nine-grade Braun-Blanquet's scale (Barkman et al. 1964). All relevés were stored in the database, using the TURBOVEG software (Hennekens 1996). The relevés were classified by divisive cluster analysis using program Juice (Tichý 2002). The numerical classification was determined using the TWINSPAN algorithm (Hill 1979). Nomenclature of the flowering plants follows Marhold & Hindák (1998) and the names of syntaxa are according to Hegedüšová Vantarová & Škodová (2014). The syntaxa missing in the mentioned publication are provided with the authors and year of the description.

Distribution
The revision of herbarium vouchers stored in 15 public herbaria showed that the species has occurred at 33 localities (Fig. 2, Appendix) in three phytogeographical districts of the Pannonian flora (Pannonicum): the Podunajská nížina lowland, the Burda hills, and Ipeľsko-rimavská brázda region. For comparison, Futák (1982) listed nine localities and Feráková (1999) listed ten localities, however, she does not specify exact localities in the vicinity of Štúrovo. During our field research, we confirmed the recent occurrence of R. pedatus at ten localities (four of them are new): saline habitats near Kamenín and Kamenný Most, in Štúrovo town (three new localities), around Chľaba village (near Modrá ryba pub and in the alluvium of Ipeľ river), in Ipeľ Basin (Pastovce, Tupá) and near the village of Koláre (new locality). This lastmentioned site represents the easternmost Slovak locality. While R. pedatus has been documented continuously since the middle of the 19 th century (Feichtinger 1862BP, 1899 until today (e.g., Feráková 1999;Melečková et al. 2013) in the salt marshes around Kamenín and Kamenný Most, in the Ipeľ basin has not been confirmed more than 60 years. The first data from the lower course of the river Ipeľ near Chľaba (phytogeographical district Burda hills) are dated from the first half of the 19 th century (Grundl 1855 BRA, 1861 BP; Feichtinger l. c.). However, it was recorded further north near Pastovce and Šahy (phytogeographical district Ipeľskorimavská brázda region) until about 80 years later (Domin 1933, 1938ined. in Futák 1982. R. pedatus was relatively common in the broader vicinity of Šahy town; eleven localities were recorded from WWII to the beginning of the 1960s (David 1987, Appendix). However, most of these localities disappeared, and during field research, we confirmed only one in the village of Tupá. Considering the relative vicinity of the R. pedatus localities around Šahy and near Koláre and the localities in northern Hungary (Sramkó & Magos 2007;Bartha et al. 2015), we could anticipate that other sites may be discovered or confirmed in this area in the future.
Ranunculus pedatus is evaluated in category "critically endangered" (CR) in actual Slovak Red List of ferns and flowering plants (Eliáš et al. 2015). The evaluation took into account only the localities near Štúrovo (salt meadows in Kamenín and Kamenný most, Fig. 3), and other historically known localities were considered disappeared. Our research confirmed about 30% of all known localities, resulting in 10 declared localities (confirmed or newly found), and 23 localities disappeared. Based on that, we propose to reclassify the species in the category "endangered" (EN) according to IUCN methodology (IUCN 2012).

Coenology
We sampled 16 phytosociological relevés in stands with presence of Ranunculus pedatus (Tab. 1). Results showed that the species was recorded in a larger number of phytocoenoses than previously reported. We confirmed the species in communities included to two classes of grassland vegetation: Festuco-Puccinellietea, and for the first time, from Molinio-Arrhenatheretea.
Šmarda (l. c.) as well as Feráková (l. c.) mentioned the species also in the alliance Puccinellion limosae representing plant communities of open and species-poor vegetation dominated by Puccinellia species, developed on strongly salt-affected soils. R. pedatus is actually mentioned in this vegetation, e.g. from Hungary [Borhidi et al. 2012; associations Matricario-Plantaginetum tenuiflorae (Soó 1933) Borhidi 1996 and Limonio-Artemisietum santonici (Soó 1927) Topa 1939], but, we did not record the species in such stands in Slovakia. Futák (1982) also mentioned the occurrence of R. pedatus in stands of the alliance Trifolio-Ranunculion pedati Slavnić 1948, but this vegetation is not present in our territory, because this is typical for saline habitats with variable moisture and slight soil salinity in the Balkans (Šilc et al. 2014;Dajić-Stevanović et al. 2016). Within the halophytic vegetation, R. pedatus is also reported from alliance Peucedano officinalis-Asterion sedifolii Borhidi 1996and Beckmannion eruciformis Soó 1933in adjacent Hungary (Molnár & Borhidi 2003Borhidi et al. 2012).
According to our findings, the majority of current sites with stands of R. pedatus, belong to the class Molinio-Arrhenatheretea including moist and mesophilic meadows and pastures.
In this vegetation class, we found the species in alliance Arrhenaterion elatioris including various types of agronomical used mesophilic meadows with a predominance of forage-valuable grasses and dicotyledonous herbs; the association also includes high-stellar stands of flood dams, ditches, artificial railway and road embankments (Hájková et al. 2014). The latter secondary types also represent stands with the occurrence of R. pedatus near Chľaba and in Štúrovo and we consider them to be atypical ruderalised stages of the association Pastinaco sativae-Arrhenatheretum (Tab. 1, relevés [10][11]. In habitats where soil was rolled up or piled up (edge of the railway line in Tupá, dam near Koláre), we recorded R. pedatus in stands close to the association Alopecuro-Festucetum pseudovinae (Tab. 1, relevés 12-13) from the alliance Cynosurion cristati. The community occurs in not salinized, arid habitats located on ridges or edges of river alluvia that are not flooded or affected by groundwater. This vegetation type represents transitional stands of the Festuco-Brometea and Molinio-Arrhenatheretea classes. The dominant species of association is Festuca pseudovina, F. rupicola, F. pratensis and Poa pratensis are also common (Hájková et al. 2014). Within this alliance, we also found the species in the vegetation of trampled habitats in the urban area of Štúrovo town (near Rego restaurant). In stand, Lolium perenne predominates and significant presence of Cynodon dactylon, Erodium cicutarium, Medicago sativa, Plantago lanceolata and Polygonum aviculare was found. This stand represents the association Lolietum perennis, according to Hájková et al. (2014) it can be considered as one from the most widespread communities in Slovakia. However, we do not have it documented by a phytocenological relevé.
R. pedatus has occupied also alluvium of the Ipeľ river (Chľaba, Pastovce) where we found it in stands of the association Poo trivialis-Alopecuretum pratensis (Tab. 1, relevés [14][15][16], alliance Deschampsion cespitosae. In Slovakia, the occurrence of the association is concentrated in the alluvium of the lower reaches of larger rivers, especially in the Východoslovenská nížina lowland and in the Ipeľ river basin (Hájková et al. 2014).
Based on herbarium data (see Appendix), it is clear that R. pedatus also grew in xerothermic stands of the Festuco-Brometea class in Slovakia, but, we did not confirm this vegetation affinity during our field research. Interestingly, Dúbravková et al (2010) recorded the species rarely in stands of the Stipetum tirsae association (alliance Festucion vallesiaceae) near the village of Szob in Hungary (Ruzsás-hegy Mt., rel. 113), which is close to the Chľaba locality in Slovakia. In addition, the occurrence of R. pedatus in the alliance Festucion valesiaceae is already mentioned in older Hungarian literature (Soó 1980