Raphidiophrys heterophryoidea
Raphidiophrys heterophryoidea, after Zlatogursky (2012)

Raphidiophrys heterophryoidea Zlatogursky, 2012

Diagnosis: Cell body spherical. Periplast composed of both radial spicules and tangential plate scales. Scales are siliceous, elliptical, with hollow inflected margin. The material forming the upper plate of the scale is present in the central part only. Spicules organic, spindle-shaped, smooth, radially arranged. Septa between two plates of a scale sometimes branching or terminating before reaching the central part of a scale.

Dimensions: cell body ca. 24 µm in diameter, plate scales 4-7 X 2-6 µm, length:width ratio 1.1-1.9; spicules 10-26 µm long.

Ecology: Fresh water; Sphagnum bog and lake sediments in Russia.

Remarks: Raphidiophrys heterophryoidea has two unique features within this genus, i.e. spindle-shaped spicules and branching septa. The plate scales of the new species cannot be attributed to any known scale type. They are similar in size to the scales of R. minuta Nicholls and Dürrschmidt, 1985, but, contrary to the latter species, not radially symmetrical (Nicholls and Dürrschmidt 1985). They are oval and not elongated, as in R. capitata Siemensma and Roijackers, 1988, and R. viridis Archer, 1867. They are similar to the scales of R. ovalis (Dürrschmidt, 1985) Siemensma and Roijackers, 1988 with regard to the partial absence of the upper plate (as seen under SEM), but have a different shape, size and length/width ratio (Siemensma and Roijackers 1988)

Raphidiophrys heterophryoidea
Raphidiophrys heterophryoidea, silica scales (shown in red); organic spicules (shown in blue). – Photomicrograph: Vasily Zlatogursky
Raphidiophrys heterophryoidea
Raphidiophrys heterophryoidea, siliceous cyst scales. Mosaic scales of outer layer (shown in light-green) and overlapping scales of inner layer (shown in dark-green) – Photomicrograph: Vasily Zlatogursky
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