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Pseudoraphidocystis dentata
P. dentata from Prokina et al., 2020

Pseudoraphidocystis dentata  Prokina, Radaykina, Mylnikov, 2020

Diagnosis: Details of the protoplast structure are unknown. Cell covered by funnel-shaped spine and
oval plate scales. Spine-scales 1.88-3.15 μm long, with conically expanding funnel-shaped distal part (1.93-2.55 μm long) and hollow cylindrical stalk (1.05-1.85 μm long). Distal edges of the widened part of scale uneven, with pointed teeth of various lengths; diameter of the widened part 2.17–3.03 μm. Stalk diameter 0.25-0.68 μm in the narrowed part; the basal part expands into the flattened base of 0.65-0.98 μm in diameter. Plate scales 2.4-2.75 × 1.32-1.36 μm, with weakly pronounced axial ridge.

Ecology: Marine. Benthic samples collected near the city of Nha Trang, Vietnam.

Remarks: P. glutinosa (Penard 1904) Mikrjukov 1997 has textureless spine-scales with even distal edges of the funnel-shaped part of the scale. P. flabellata (Dürrschmidt 1987) Mikrjukov 1997 and P. umbraculiformis (Dürrschmidt 1987) Mikrjukov 1997 differ by having radial ribs, as well as by the weakly developed and short stalk; in the subspecies P. flabellata ssp. novae-zelandiae, the foot is completely absent. P. umbraculiformis is also distinguished by having a short stalk. Small funnel-shaped spine-scales are also characteristic of members of the genus Raphidocystis, but differ by having the second type of spine scales, long tube- or pipette-shaped, as well as by the morphology of the plate-scales with a reticular structure and a wide hollow marginal rim.

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