Acanthocystis costata Zlatogursky, 2015

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 costata Zlatogursky, 2015 ( Fig. 2F–I)

Description: Straight or slightly curved spine scales consist of a hollow shaft and circular base. Shaft is 5.0– 10.78 µm in length and 0.29–0.34 µm in diameter, base is 0.96–1.21 µm in diameter. Tip of shaft divided on 4–6 furcae (0.43–0.65 µm in length). Oval plate scales are 3.18–3.78×1.59–2.15 µm, with concave lateral sides, medial thickening (0.55–0.72 µm in length) and dense margins. Some plate scales have numerous small granules ( Fig. 2I), others are ornamented with about 50 short (0.15–0.27 µm) radial slits ( Fig. 1H ).

Remarks: This species was previously noted only once from the freshwater pool in the greenhouse of the botanical garden of St. Petersburg State University, St. Petersburg, Russia ( Zlatogursky 2015). Morphology of observed scales completely corresponds with the original description.

Figures

Fig. 1. Morphology of living cells of some observed centrohelid species (DIC):A – Acanthocystis nichollsi; B – A. pectinata (from plant debris and silt of Usman’ River); C – A. turfacea (from plant debris and silt of Lake Chistoye); D – Raphidocystis symmetrica (from plant debris and silt of Lake Chistoye); E – Choanocystis aculeata (from sand of Lake Maklok); F – Raphidiophrys capitata (from sand of Lake Maklok). Abbreviations: ax – axopodia; pr – protoplast; sc – scales. Scale bar: 20 µm.