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Oligosphaeridium saghirum
Oligosphaeridium saghirum Slimani et al., 2012, p.342–344, fig.4A–J.
Holotype: Slimani et al., 2012, fig.4A–F.
Age: late Maastrichtian–Danian.
Original description (Slimani et al., 2012)
Holotype. Sample OH 0, slide 2, England Finder D39 (Fig. 4A–F).
Type locality and bed. Ouled Haddou section, north of Taza, northern Morocco; marl 10 m below the K/T boundary, upper Maastrichtian.
Etymology. From ‘saghir’ (Arabic): small, with reference to the small size of the cyst.
Diagnosis. A small, smooth and thin-walled Oligosphaeridium species. Distal extremities of the hollow processes flared and funnel-shaped with entire to slightly undulate distal margins. Archeopyle apical of type (tA); operculum mostly free, sporadically in place.
Description. The small, chorate dinoflagellate cyst has an ovoid to spherical central body. The thin, smooth, hyalin autophragm has a maximum thickness of 1 μm. The thin-walled and hollow processes are simple and tubiform. The processes are distally open and flared or funnel-shaped with an entire to slightly undulate margin (Fig. 4C, G). The number of processes is generally 18 and their position is intratabular. The length of the processes is usually smaller than the diameter of the central body. The width and length of the processes is approximately constant on a specimen, but varies slightly within the species. The observed tabulation is gonyaulacoid (4′, 6′, 6′′, 1p, 1′′) and is indicated by the position of the processes and the archeopyle. The cingular and sulcal processes are absent. The archeopyle is apical and is of type (tA). The margin of the archeopyle is distinctly zig-zag shaped. The operculum is simple and mostly free. The operculum consists of four plates indicated by four intratabular processes (Fig. 4C).
Dimensions. Holotype: central body diameter, 22 μm; process length, 13–14 μm. Range: central body diameter, 20(22)26 μm; average length of process, 13(16)18 μm (10 specimens measured).
Remarks. Oligosphaeridium saghirum sp. nov. is identical to ?Homotryblium sp. of Brinkhuis & Zachariasse (1988) in being small and in having distally flared and funnel-shaped processes with entire to slightly undulate distal margins. Oligosphaeridium levimarginatum Marheinecke, 1992 is of approximately the same size, but differs in the buccinate shape of its processes. The distal extremities of the processes of Oligosphaeridium buciniferum Corradini, 1973 appear similar. However, the dimensions of the cyst and processes of the latter species are twice as large.
Stratigraphic occurrence. Samples OH 0–16, planktic foraminiferal Abathomphalus mayaroensis Zone (upper Maastrichtian), Guembelitria cretacea and Parvularugoglobigerina eugubina zones (lower Danian), Ouled Haddou section. Planktic foraminiferal Abathomphalus mayaroensis Zone (upper Maastrichtian), from Guembelitria cretacea to Neogloboquadrina pseudobulloides zones (Danian), El Kef section (Tunisia; Brinkhuis & Zachariasse 1988
Holotype: Slimani et al., 2012, fig.4A–F.
Age: late Maastrichtian–Danian.
Original description (Slimani et al., 2012)
Holotype. Sample OH 0, slide 2, England Finder D39 (Fig. 4A–F).
Type locality and bed. Ouled Haddou section, north of Taza, northern Morocco; marl 10 m below the K/T boundary, upper Maastrichtian.
Etymology. From ‘saghir’ (Arabic): small, with reference to the small size of the cyst.
Diagnosis. A small, smooth and thin-walled Oligosphaeridium species. Distal extremities of the hollow processes flared and funnel-shaped with entire to slightly undulate distal margins. Archeopyle apical of type (tA); operculum mostly free, sporadically in place.
Description. The small, chorate dinoflagellate cyst has an ovoid to spherical central body. The thin, smooth, hyalin autophragm has a maximum thickness of 1 μm. The thin-walled and hollow processes are simple and tubiform. The processes are distally open and flared or funnel-shaped with an entire to slightly undulate margin (Fig. 4C, G). The number of processes is generally 18 and their position is intratabular. The length of the processes is usually smaller than the diameter of the central body. The width and length of the processes is approximately constant on a specimen, but varies slightly within the species. The observed tabulation is gonyaulacoid (4′, 6′, 6′′, 1p, 1′′) and is indicated by the position of the processes and the archeopyle. The cingular and sulcal processes are absent. The archeopyle is apical and is of type (tA). The margin of the archeopyle is distinctly zig-zag shaped. The operculum is simple and mostly free. The operculum consists of four plates indicated by four intratabular processes (Fig. 4C).
Dimensions. Holotype: central body diameter, 22 μm; process length, 13–14 μm. Range: central body diameter, 20(22)26 μm; average length of process, 13(16)18 μm (10 specimens measured).
Remarks. Oligosphaeridium saghirum sp. nov. is identical to ?Homotryblium sp. of Brinkhuis & Zachariasse (1988) in being small and in having distally flared and funnel-shaped processes with entire to slightly undulate distal margins. Oligosphaeridium levimarginatum Marheinecke, 1992 is of approximately the same size, but differs in the buccinate shape of its processes. The distal extremities of the processes of Oligosphaeridium buciniferum Corradini, 1973 appear similar. However, the dimensions of the cyst and processes of the latter species are twice as large.
Stratigraphic occurrence. Samples OH 0–16, planktic foraminiferal Abathomphalus mayaroensis Zone (upper Maastrichtian), Guembelitria cretacea and Parvularugoglobigerina eugubina zones (lower Danian), Ouled Haddou section. Planktic foraminiferal Abathomphalus mayaroensis Zone (upper Maastrichtian), from Guembelitria cretacea to Neogloboquadrina pseudobulloides zones (Danian), El Kef section (Tunisia; Brinkhuis & Zachariasse 1988