Ecological and geographical features of the Western Pamir-Alai endemic Ranunculus botschantzevii Ovcz

New information is presented about the endemic of the western Pamir-Alai Bochantsev's buttercup. As a result of the revision of herbarium materials and field studies, new locations of this species were identified, and distribution data were updated. The features of ecological limitation and some morphological and eco-biomorphological characteristics of plants from different parts of the area are compared. Taking into account the vision of modern taxonomy, the taxonomic position is presented for the first time, as well as a list of collected samples from all known locations of this species. Ranunculus botschantzevii is an endemic plant known from several locations in the western part of the Pamir-Alai on the spurs of the Gissar (Uzbekistan) and Zeravshan (Tajikistan) ranges. This is an autochthonous representative of the mountain Central Asian flora, which emerged in the process of regional adaptive diversification of ancient Mediterranean predecessors. Until the 1970s of the last century, Bochantsev's buttercup was known only from the Beshnau mountains (Gissar range), from where it had been described. Later, in the process of collecting materials for Flora of Tajikistan (1953), the second location of this species was found in the Valangi-Daroz tract (Mogian River). The research materials were the results of an audit of the herbarium collections of the genus Ranunculus L. in Middle Asia (TASH, TAD, LE, KG, AA, MW, LE, TK), as well as the results obtained during the expeditionary and stationary work of the authors in Uzbekistan, Tajikistan and Kyrgyzstan in 2017-2019. Field studies were carried out by the route method, conducted on the Baysuntau ridge (Uzbekistan) in the second half of May 2012 and 2019 in the area of Hodzha-Gurgur-ata mountain, as well as in the Machai-Darya river basin, at an altitude of 2300-2700 m above sea level. Studies on the Zeravshan ridge (Tajikistan) were carried out in June 2019 in the vicinities of Iskanderkul Lake and to the south along the Kanchoch River, at an altitude of 2500-3050 m above sea level. Subsequently, the geographical coordinates of the previously known locations were refined, and all information was entered into the database for subsequent point mapping. Field surveys made it possible to clarify the ecological-phytocoenotic limitation and some morphological parameters (especially the characteristics of basal leaves, the degree of branching of stems, plant height, etc.) in different parts of the area of Bochantsev's buttercup. A more diverse than the previously known spectrum of morphological variability of basal leaves was found. It was noted that in the western and eastern parts of the area, the general habitual changes of this species manifest themselves in different ways, as well as environmental features. Signs of ephemeroidity in this species are combined with the characteristics of a typical alpine plant. Obviously, varying the boundaries of altitudinal distribution and some ecological and morphological plasticity of the buttercup are directly related to the possibilities of expansion and displacement of phenological phases in the summer months, in contrast to real ephemeroid plants. At present, four main locations of Ranunculus botschantzevii Bochantsev's buttercup are known within the borders of Uzbekistan, and two are within Tajikistan. As a result of our field surveys, the species was found at two points at the Baysuntau ridge, as well as in a new place at the Zeravshan ridge. Presumably, the distribution of this endemic is limited to the mountains of the western part of the Pamir-Alai. Despite the fact that this buttercup is rare, its new findings are likely. Since the habitats of Bochantsev's buttercup are inaccessible and are not subject to direct anthropogenic impact, it does not yet need special protection measures. However, its features such as narrow-local distribution, rare occurrence and small populations require, at least, monitoring attention. The paper contains 4 Figures and 22 References. Acknowledgments: The authors express the gratitude to the National Center for Biodiversity and Biosafety Committee for Environmental Protection under the Government of the Republic of Tajikistan for their cooperation. The Authors declare no conflict of interest.

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