Hymenomonas uralensis Ignatenko & Yatsenko-Stepanova sp. nov. (Fig. 15)

Coccoliths are elliptical muroliths. Each coccoliths composed of an organic base plate and calcified elements. The base of the coccolith (0.93–1.2 × 0.8–0.96 µm, n=15) has a jagged edge, followed by a tubular part with more or less straight sides and the expanding part (1.3–1.6 × 0.97–1.3 µm) is formed by overlapping elements. The height of the coccolith is 0.36–0.51 µm, the width of the rim is 0.22–0.3 µm. In most coccoliths a single rim element at each end of the coccolith is extended distally as a rectangular block protruding above the rim (width 0.18–0.33 µm, height 0.25–0.43 µm).

Type: —The specimen with Hymenomonas uralensis coccoliths on SEM stub number 49_I_3 deposited at the Herbarium of the Steppe Institute of the Ural Branch of the Russian Academy of Sciences, Orenburg (ORIS). Material from the Ural River (51°25ʼ55”N, 56°28ʼ58”E), Orenburg Region, Russia. Sample collected 27th of July, 2021, by M. Ignatenko .

Type Locality: —RUSSIA: Orenburg region, Ural River. 51°25ʼ55”N, 56°28ʼ58”E. 27 July 2021.

Etymology: — Hymenomonas uralensis is named after the Ural River, where this species was discovered.

Distribution: —Besides the type locality this species was found from the backwater of the Ural River in the vicinity of the Nikolskoye village (see Table 2).