Guide to Gogorevia

The genus Gogorevia was recognized based on genomic and morphologic data (Kulikovsky et al. 2020). The genus includes the former Achnanthes exigua Grunow (= Achnanthidium exiguum (Grunow) Czarnecki), and had also been transferred to Lemnicola (Plinski and Witkowski 2011, Shi et al. 2020). Gogorevia differs from Achnanthidium and Lemnicola by the shape of the valves, uniseriate striae, raphe morphology, and the presence of a distinct sternum.

Valves ends ends are rostrate, with broadly rounded apices. The axial area is narrow, linear, and opens to a broad central area.

Raphe valves possess a narrow, rectangular to wedge-shaped fascia that may extend to the valve margin in some species. Striae are radiate, becoming more strongly radiate near the apices. Striae are uniseriate and composed of small, rounded areolae. The raphe is straight, with straight, expanded proximal raphe ends. The distal raphe ends are deflected to opposite sides and terminating in expanded pores. Internally, the distal raphe ends terminate in helictoglossae.

Rapheless valves possess an asymmetric central area. One side of the central area has a hyaline area, while the other side of has more broadly spaced, uniseriate striae. The striae are nearly parallel, becoming more radiate near the apices. Areolae are round to elongated. Externally, the narrow sternum is evident.