Korotnevella jeppesenii
K. jeppesenii, after Van Wichelen & Vanormelingen, 2016

Korotnevella jeppesenii Van Wichelen & Vanormelingen, 2016

Diagnosis: Locomotive form dactylopodial with a length of 16–41 µm and a width of 6–20 µm. Vesicular nucleus about 2–3 µm in diameter with one slightly eccentrically located nucleolus. Floating form radial, maximally 16 µm long, containing up to 10 long, pointed pseudopodia. Scales elliptical, disk-shaped with a length of 193–327 nm, a width of 124–203 nm, carrying a central spine of 47–97 nm in length. Amoebae occasionally form aggregates during cultivation. Cysts never observed.

Ecology: Presumably highly specific grazer of Microcystis, similar to K. pelagolacustris. Type locality: Strain A4DVDPB was isolated from a Microcystis bloom sample from a fish pond (Drie Vijvers) in De Panne (Belgium)). Strain A1JEPDK was isolated from a Microcystis bloom sample originating from a mesocosm in Silkeborg (Denmark).

Differential diagnosis: K. jeppesenii closely resembles K. diskophora (Smirnov 1999) in its general morphology and size. However the length of the scales is smaller (mean 277) than in K. diskophora (about 350). Its globular floating form with radiating pseudopodia also differs from K. diskophora’s atypical irregular one. Moreover, K. jeppesenii occurs in Microcystis blooms where it specifically feeds on Microcystis cells whereas K. diskophora is a bacterivorous bottom-dweller (Smirnov 1999). K. pelagolacustris is larger in size (max. 65 µm), has larger scales (max. 391 nm) with larger spines (max. 163 nm) and differs in 18S rDNA sequence.

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