Rabdiaster reticulata
Rabdiaster reticulata
R. reticulata, (l.) from Siemensma (1991) and (r.) Nicholls (1902)

Rabdiaster reticulata (Thomsen, 1979) Mikrjukov, 1999. emend. Nicholls, 2012
( = Pinaciophora reticulata Thomsen, 1979)
( = Rabdiophrys reticulata (Thomsen, 1979) Roijackers & Siemensma, 1988)

Diagnosis: Cells 15 – 25 µm in diameter, with tubular spine-scales 2 – 6 µm long with a solid disc-like base 0.5 – 0.7 µm in diameter and about 0.1 µm thick. The middle region of the spine shaft with parallel walls in optical cross-section, about 0.35 µm in diameter; some spines with internal short, curved rib-like thickenings at irregular intervals throughout the length of the spine shaft. Distal end of the spine-scales flared to about 0.35 – 0.65 µm in diameter with a scalloped rim ornamented with 3-5 tooth-like projections. Plate-scales, 2.5 – 3.2 µm in diameter, comprised of a double layer of siliceous sheeting, unornamented or with a few small depressions in the distal sheet (visible in TEM images of obliquely oriented scales). The space between the double layer is filled with a maze-like pattern of ribs and/or hexagonal or polygonal meshes revealed in TEM images as electron-dense dark lines and forming an elaborate ribbed network  with the largest and more completely structured meshes located near the centre of the scale. Aberrant plate-scales  with non-circular outlines (smaller with rounded polygonal outlines) occasionally present.

Type location: Marine, Dybso Fjord (Denmark).

Rabdiaster reticulata
Rabdiaster reticulata
R. reticulata, from Nicholls (1902)
Recent posts

Difflugia key ovoid

Difflugia Ovoid Group Key characters: Test in cross section rounded. Test with rounded fundus. Pseudostome with smooth circular edge. Test ovoid. 1 Test with collar

Read More »

Difflugia: ovoid tests

Difflugia – group 1 Test < 60 µm. Test in cross section rounded. Test with rounded fundus. Pseudostome with smooth circular edge. Test not spherical

Read More »

Difflugia ampla

Difflugia ampla, after Rampi, 1950 (l) and Gauthier-Lièvre et Thomas, 1958 (r) Difflugia ampla Rampi, 1950 Diagnosis: Test broadly pyriform, with a wide and rounded

Read More »

Difflugia parva

Difflugia parva, from Gauthier-Lièvre et Thomas, 1958 Difflugia parva  (Thomas, 1954) Ogden, 1983 = Difflugia oblonga var. parva Thomas, 1954 Diagnosis: Test pyriform, tapering evenly from

Read More »