Belonocystis marina Klimov et Zlatogursky, 2016


Diagnosis: Spherical cells 6-8 µm in diameter with eccentric nucleus about 3-5 µm and a spherical nucleolus. Contractile vacuole absent. Cytoplasm is filled with small granules, yellowish crystals and food vacuoles. Floating or moving along the substratum with fine locomotive pseudopodia. Tightly packed scales surround the cell, being attached to short outgrowths on the cell surface. Individual scales are racket-shaped in optical section, 9-16 µm in length. The bulbous base of the scale is empty and has a latticed wall, consisting of fibrils which are connected with similar fibrils forming a pointed spike. The basal part also bears three circular latticed structures – the “skirts” with a proximal one being less electron-dense and two distal ones being denser and bearing thickened rims. May form large multinucleate cells that show amoeboid movement.


Ecology: Marine; tolerates salinities from 10 to 60‰ in culture. Type locality: Salt marsh near island Matrenin, Chupa inlet, Kandalaksha Bay, the White Sea.


Remarks: Differs from the two other described species because the scale bases are oval in optical section, not pentagonal (B. tubistella) or triangular (B. quadrangularis), and because the scales lack struts supporting the spike, but have “skirts” around the scale bases (the latter two features visible by electron microscopy).