Species diversity of Bacillariophyta in the Nyzhniosulsky National Nature Park (Ukraine)

Results of the study of Bacillariophyta in the water bodies of the Nyzhnyosulsky National Nature Park (NsNNP, Poltava Region, Ukraine) are presented. 38 samples of plankton, benthos, and periphyton were collected during various seasons of 2016-2017. Diatoms were investigated by means of light and scanning electron microscopy. A total of 242 species of diatoms were identified; they belong to 3 classes, 14 orders, 31 families, and 62 genera. The number of diatom species varied widely in the studied water bodies: from 26 (in the Borys R.) to 223 (in the Sula R.) species depending on the type and ecological state of the water body. In taxonomic structure, class Bacillariophyceae (95.9 %) was the most diverse compared to Mediophyceae (2.5 %) and Coscinodiscophyceae (1.6 %). Leading families include Cymbellaceae, Naviculaceae, Bacillariaceae, Gomphonemataceae, Fragilariaceae, Stauroneidaceae, Pinnulariaceae, and Surirellaceae. Genera Navicula, Gomphonema, Nitzschia, and Cymbella were the richest in species. This study increased the number of NsNNP diatoms by 57.4 %; taking the literature data into account, a total of 285 Bacillariophyta species are known for the park water bodies. A number of new taxa were revealed confirming the role of this protected area in nature conservation of the region. 15 species of Bacillariophyta found in the water bodies of the park are first cited for Ukraine. 16 species are new for the Forest-Steppe zone of Ukraine and 10 for the Left-Bank Forest-Steppe. 2 new nomenclature-taxonomic combinations are proposed: Surirella hibernica (W. Smith) D. Kapustin and O.Kryvosheia comb. nov. and Iconella amphioxys (W. Smith) D. Kapustin and O. Kryvosheia comb. nov.