Korotnevella leshevi, Udalov & Völcker, 2022

Udalov, Ilya A. & Völcker, Eckhard, 2022, Is scale’s structure still a good character to delimitate species of Amoebozoa? case of the genus Korotnevella (Amoebozoa, Dactylopodida), Organisms Diversity & Evolution (New York, N. Y.) 22 (1), pp. 17-33 : 21

Korotnevella leshevi sp. nov.

Locomotive cells have the shape of an irregular triangle ( Fig. 1A ) or rectangle ( Fig. 1B, C ). Cells form short subpseudopodia during locomotion ( Fig. 1A–C ). Length of locomotive form is 28–66 μm (average 50.2 μm), breadth is 10–29 μm (average 16.1 μm), and L/B ratio is 1.6–5.1 (average 3.3). Single nucleus of ellipsoid shape ( Fig. 1D ) is 6.9–9.4 μm in length (average 8.2 μm) and 4.0–6.6 μm in breadth (average 5.2 μm). The nucleolus is ball-shaped ( Fig. 1D ), while in some cells, it contains a small transparent lacuna ( Fig. 1D ). The diameter of the nucleolus is 0.9–3.1 μm (average 2.0 μm). Cells have two contractile vacuoles ( Fig. 2A, B ).

In our cultures, amoebae form cysts with a thick cyst wall ( Fig. 1E ). The diameter of the cytoplasmic body of the encysted cell is 11 ‒ 15 μm (average 12.4 μm), while the diameter of the cyst including its wall is 14 ‒ 20 μm (average 15.8 μm).

Cell surface is covered with two types of scales: large basket-shaped and small dish-shaped ( Fig. 1F, G ). The length of the basket-shaped scales is 372–562 nm (average 456 nm); breadth 173–287 nm (average 240 nm); and height 130–221 nm (average 175 nm). The length of the dish-shaped scales is 78–140 nm (average 107 nm); breadth 42–85 nm (average 60 nm); and height 12–28 nm (average 19 nm). Large scales include basal plate and latticework basket in the shape of a closed hammock supported with two apical and ten lateral columns ( Fig. 1F, G ).

Figures

Fig.1 Korotnevella leshevi sp. nov. Light (phase contrast (A–C) and DIC (D, E)) and electron micrographs (critical point dried cells, SEM (F), and whole mounts of air-dried cells, TEM (G)). A–C Locomotive forms in a Petri dish. D Cell compressed with coverslip showing nucleus. E Cyst compressed with a coverslip. F A region of cell coverings showing scales. G Whole mounts of air-dried scales. Arrows indicate a direction of cell movement. Abbreviations: ac, apical column; cv, contractile vacuole; ds, dish-shaped scale; bp, basal plate; l, lacuna; lc, lateral column; lb, latticework basket; ls, layer of scales; n, nucleus; nu, nucleolus; pf, perforated flange. Scale bars=10 μm (A–E), 0.1 μm (F, G)

Fig. 2 Light micrographs of Korotnevella sp. 1 (A–F), Korotnevella sp. 2 (G–K), K. hortobotanici sp. nov. (L–P), and Korotnevella sp. 3 (Q–V). Locomotive forms in a Petri dish, phase contrast (A–D, G, H, L–N, Q–S). Nucleus, DIC (E, I–K, O, P, T, U). Cyst, DIC (F,