Pterocystis scaposa (Dürrschmidt, 1987) Siemensma, 1991
Diagnosis: Periplast, ca. 10 µm in diameter (measurement based on whole mount); details of protoplast unknown. Scales of two types. Plate scales, 1.2-1.5 X 0.6-0.8 µm, are patternless, except for a vestigially developed axial thickening. Spine scales, (1.1) 1.9-2.3 (7.2) µm long, consist of shaft, base-plate and lateral wings. Shaft narrow, non tubular, tapering to a blunt apex. Wings, ca. 0.08 µm broad, to be found on either side of the shaft. They are broadest just beyond the base-plate but then narrow gradually towards the distal end of the shaft. Base-plate, ca. 0.5 µm in diameter, reniform or heart-shaped, surrounded by a narrow peripheral rim.
Ecology: from the Banado Cruces, southern Chile (Dürrschmidt, 1985). Distribution: Chile, Sri Lanka.
Remarks: A. scaposa is remarkable in that two otherwise always separate characteristics are combined in its spine scales: lateral wings and heart-shaped base-plates.
Variation within A. scaposa is most noticeable with regard to the size of the spine scales. Whereas those from the majority of the Chilean habitats and from Sri Lanka vary from 1.9 to 2.3 µm, those from a swamp near Puerto Montt, Chile are 1.2 µm long. There is, however, no reason to believe that this difference should be considered anything but infraspecific variation. It may indicate the presence of different clones, or different stages in the cell or life cycle.