Acanthocystis aff. amura Zlatogursky et al., 2017

Prokina, Kristina I., Zagumyonnyi, Dmitry G. & Tikhonenkov, Denis V., 2018, Centrohelid Heliozoans (Centroplasthelida Febvre-Chevalier et Febvre, 1984) from Different Types of Freshwater Bodies in the Middle Russian Forest-steppe, Acta Protozoologica 57 (4), pp. 243-266 : 245

Acanthocystis aff. amura Zlatogursky et al., 2017 ( Fig. 2A–E)

Description: Spine scale consists of a straight cylindrical shaft and a circular flattened base. Shaft is 3.88– 5.98 µm in length, 0.12–0.21 µm in diameter, base is 0.63–0.93 µm in diameter. Tip of shaft divided into 4 rounded furcae ( Fig. 2D) or hooks ( Fig. 2C) 0.10–0.16 µm in length. Oval plate scales are 1.98–2.47×1.42– 1.68 µm, with medial thickening (0.75–1.51×0.12–0.19 µm) and dense margins.

Remarks: A. amura was previously found only in the Far East and Orenburg Region, Russia ( Zlatogursky et al. 2017). The presence of two types of spine scales was noted for this species: long spine scales (1.3–6.2 µm) with rounded hooks on tips; short spine scales (1.0–3.4 µm) with 3–5 pointed furcae. We observed only long spine scales with round hooks or round furcae. Morphology of plate scales agreed well with the original description.