Belonocystis quadrangularis, Nicholls, 2012

Nicholls, Kenneth H., 2012, Structure of Organic Spines in the Rhizarian Protist Belonocystis tubistella Rainer, 1968, and a Description of Belonocystis quadrangularis n. sp. (Cercozoa, Insertae Sedis), Acta Protozoologica 51 (1), pp. 21-28 : 23

Belonocystis quadrangularis n. sp.; Fig. 3a–j

Diagnosis: Cells spherical, 5–9 µm in diameter with a prominent eccentric nucleus 3–4 µm in diameter and 1–3 contractile vacuoles up to 3 µm in diameter. Cells, lacking chloroplasts, phagotrophic, motility by fine pseudopodia, covered with a single type of organic spine consisting of a long, tapered, hollow shaft with a pyramid-shaped base comprised of four arms or struts 1.6–1.8 µm long, originating from an irregularly shaped nodal swelling at the base of the main spine shaft. Base of the main spine shaft distal to the basal struts, 0.23–0.30 µm in diameter and tapering over a total length of 15–20 µm to a distal tip that is about 0.07 µm in diameter.

Etymology: The specific epithet ( quadrangularis ) denotes the 4-sided pyramidal structure of the spine bases of this taxon comprised of four spreading struts serving to anchor the spine near the surface of the cell (L. quadrangularis – four-sided, quadrangular).

Type specimen: Holotype, Fig. 2g . Several paratype specimens mounted in Canada Balsam on a glass slide, is retained at the Canadian Museum of Nature (Invertebrate Zoology Division), Ottawa , Ontario, Canada; Catalogue No CMNI-2012-000x.

Type locality: Pond #7, Snowdon Township, Haliburton County, Ontario, Canada 44°49′28″N, 78°32′00″W .

Material from type locality: Retained by the author in sample No. V-553, collected by K. Nicholls, 24 October, 1983.

Figures

Fig. 2. Belonocystis tubistella scale structure. a–c – whole cells, died, TEM images showing the investiture of radiating spines; d–f – diagrammatic depiction of the arrangement (d) and structure of spine bases showing meshed structure of an intact scale base (e) and the collapsed state of a dried spine base (f). The meshed structure is not included in f, to visualize better the collapsed shape of the spine; g–h – TEM images showing the meshed structure of the spine bases. The arrows in h are examples of the distorted (high “shoulder” effect) shape of collapsed spine bases (as illustrated with the arrow in f).