Turriplaca biparta (Nicholls, 2013)

Diagnosis: Cells spherical, 8-12 um in diameter, covered with both plate- and spine-scales (visible in high magnification, phase contrast light microscopy). Movement is a very slow tumbling action mediated by several fine filopodia about 2 times the cell diameter in length. Plate scales circular to occasionally slight elliptical, 1.7-3.5 µm in diameter (most commonly 2.5-3 µm in diameter) with a slightly thickened rim about 0.8 µm wide. Proximal surface of plate-scales concave, lacking ornamentation; distal surface convex with 3-7 circular holes 0.15-0.25 µm in diameter. Spine-scales in two parts; the basal portion, about 2/5 of the total scale length, consists of a circular base-plate 1.0-1.2 µm in diameter from which arises a sub-cylindrical (weakly hour-glass-shaped) tube of about 0.7 µm diameter in the slightly constricted mid-region. This structure terminates in a flared apex with 3-6 marginal “teeth”. The longer apical portion consists of a sub-cylindrical shaft (slightly constricted in the mid-region) with a mid-section diameter of about 0.3 µm and with 2-3 longitudinal ribs that terminate at the apex in 2-3 small tooth-like projections. Total spine-scale length, 3.0-6.5 µm (most commonly, 4-5 µm).

Habitat: Marine. Benthic near-shore sand, north shore, Sable Island, (Atlantic Ocean, Nova Scotia); Salinity = 33 ppt; collected 20 August, 2007.

Remarks: Plate-scales of T. biparta bear some resemblance to those of Pinaciophora rubicunda (Hertwig & Lesser, 1874) Roijackers & Siemensma, 1988, Thomseniophora paucipora and P. tasmanica, Croome. P. rubicunda, however, has larger and predominantly elliptical scales with much larger and more plentiful centrally located pores on the distal surface. The plate-scales of T. biparta are larger with larger and differently arranged central pores than those of either T. paucipora or T. tasmanica. The highly characteristic bipartite spine-scales of T. biparta are very unlike those of any previously described rotosphaerid species.