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Rhombodinium subtile
Rhombodinium subtile Wilson, 1988
Holotype: Wilson 1988: Plate 18, Fig. 2;
Locus typicus: Waipawa Section, Hawkes Bay, New Zealand
Stratum typicum: Waipawan Stage (Lower Eocene)
Age: Early Eocene (Waipawan)
Original description: Cyst intermediate to large, subrhomboidal, angular, with thin, pale, delicate periphragm and endophragm. Horns fairly prominent; apical horn somewhat rectangular (length up to 15 µm) with a flat occasionally serrate tip; left antapical horn relatively prominent, acuminate (length up to 20 µm); right antapical horn reduced, acuminate (length up to l0 µm). Lateral horns well developed (length up to 20 µm), broad with a notched tip; small solid processes (length up to 3 µm) typically occur at distal extremities of lateral horns and, less conspicuously, on other horns. Periphragm surface smooth, apart from horn extremities, frequently folded. Endophragm smooth, somewhat difficult to discern, in close contact with periphragm, except at horn bases. Archeopyle intercalary, quadrangular, somewhat rounded; operculum free, endoperculum and perioperculum in close contact. Paracingulum indicated by notches in tips of lateral horns and occasionally by somewhat irregular transverse folds in central part of periphragm. Parasulcus not usually indicated.
Dimensions: Holotype: overall length 97 µm, breadth 103 µm, length of endocyst 68 µm, breadth 76 µm. Range: overall length 81(92)111 µm, breadth 86(96)108 µm (n = 7).
Distribution: Recorded only from the Waipawan Stage, Lower Eocene
Discussion: The species is characterised by its very thin, delicate, smooth, frequently folded wall and by the very small processes on the distal extremities of the horns. It represents the earliest occurrence of an essentially smooth-walled member of the Wetzeliella group in the New Zealand sedimentary sequence.
Holotype: Wilson 1988: Plate 18, Fig. 2;
Locus typicus: Waipawa Section, Hawkes Bay, New Zealand
Stratum typicum: Waipawan Stage (Lower Eocene)
Age: Early Eocene (Waipawan)
Original description: Cyst intermediate to large, subrhomboidal, angular, with thin, pale, delicate periphragm and endophragm. Horns fairly prominent; apical horn somewhat rectangular (length up to 15 µm) with a flat occasionally serrate tip; left antapical horn relatively prominent, acuminate (length up to 20 µm); right antapical horn reduced, acuminate (length up to l0 µm). Lateral horns well developed (length up to 20 µm), broad with a notched tip; small solid processes (length up to 3 µm) typically occur at distal extremities of lateral horns and, less conspicuously, on other horns. Periphragm surface smooth, apart from horn extremities, frequently folded. Endophragm smooth, somewhat difficult to discern, in close contact with periphragm, except at horn bases. Archeopyle intercalary, quadrangular, somewhat rounded; operculum free, endoperculum and perioperculum in close contact. Paracingulum indicated by notches in tips of lateral horns and occasionally by somewhat irregular transverse folds in central part of periphragm. Parasulcus not usually indicated.
Dimensions: Holotype: overall length 97 µm, breadth 103 µm, length of endocyst 68 µm, breadth 76 µm. Range: overall length 81(92)111 µm, breadth 86(96)108 µm (n = 7).
Distribution: Recorded only from the Waipawan Stage, Lower Eocene
Discussion: The species is characterised by its very thin, delicate, smooth, frequently folded wall and by the very small processes on the distal extremities of the horns. It represents the earliest occurrence of an essentially smooth-walled member of the Wetzeliella group in the New Zealand sedimentary sequence.