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Batiacasphaera bergenensis
Batiacasphaera bergenensis, Schreck and Matthiessen, 2014, p.102–103, pl.1, figs.1–16.
Holotype: Schreck and Matthiessen, 2014, pl.1, figs.1–9.
Type locality: ODP Site 907, eastern Iceland Plateau (69°14.989′N, 12°41.894′W).
Stratigraphic horizon: ODP Hole 907A, 169.10 mbsf; lower Serravallian (upper Middle Miocene), Subchron C5ABn, calibrated age 13.39 Ma.
Stratigraphic occurrence: In Iceland Sea ODP Hole 907A, Batiacasphaera bergenensis sp. nov. ranges from the uppermost Langhian (13.68 Ma) through lower Tortonian (11.09 Ma).
Age: latest Langhian–early Tortonian.
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Original description: [Schreck and Matthiessen, 2014]:
Diagnosis:
A species of Batiacasphaera having a spherical central body, thin solid inner wall layer and thicker outer wall of non-tabular irregular high (up to 5 μm), narrow solid septa which form a continuous tectum of closely adjoining blisters with polygonal to elongate outline.
Archeopyle apical, and operculum free, other tabular features absent.
Description:
Small to medium sized holocavate proximate cyst with a spherical central body, but undulating outline in cross-section (Plate I, 4, 5 and 11). The cyst wall consists of two layers; a thin (b1 μm) pedium that appears solid under light microscope, and a luxuria, which comprises non-tabular, distributed solid septa of uneven height (c. 2–5 μm on individual specimens) that expand distally to create a tectum in the form of numerous closely adjoining blisters. Cysts are rarely crumpled or folded due to the thick wall. Where they branch distally, septa are indented, and sometimes slightly thickened as seen under light microscope. Larger specimens usually have higher septa (Fig. 5), and variation of septa height occurring on the same cyst and indentation at intersections account for the undulating outline of the central body in optical section. Under SEM, individual septa may additionally branch and/or fuse at random height over entire length (Plate I, 15). Spacing between septa varies on individual specimens. The variations in septa height and spacing result in a continuous but irregular tectum comprising densely spaced blisters. The shape of blisters is irregular rounded polygonal to rectangular, sometimes elongated with significant variations in size (Plate I, 9 and 14), and they may appear as a reticulum under light microscope due to ‘LO’ effect (Plate I, 8 and 9).
The distribution pattern of blisters does not reflect any tabulation pattern. This ornament spreads over the entire surface of the cyst without variation, and extends to the archeopyle margins without modification.
The archeopyle is apical with a low to moderately angular principal suture that appears slightly thickened (Plate I, 1, 12 and 16), and lacks accessory sutures. The shape of the archeopyle indicates that it is presumably formed by loss of 3 apical plates. The operculum is free and was not observed on any specimen.
There is no other expression of tabulation.
Dimensions:
Holotype: Central body maximum diameter (without luxuria), 36 μm, maximum septa height, 4 μm.
Range: Central body maximum diameter (without luxuria), 21(30.6)36 μm, maximum septa height, 2(3.5)5 μm. Thirty-five specimens were measured (see also Fig. 5).
Affinities/Discussion:
This species has been assigned to the genus Batiacasphaera due to its spherical central body, low surface ornament, and apical archeopyle presumably consisting of 3 apical plates. It possesses a slightly thickened principal archeopyle suture, which is typical for some Batiacasphaera species. It differs from all other Batiacasphaera species in having a cyst wall composed of a thin pedium that supports a luxuria of solid, high septa which form a tectum rather than two closely appressed wall layers as typical for the genus. In Kallosphaeridium de Coninck 1969 the multiplate apical archeopyle is attached to the sulcus. Blysmatodinium argoi McMinn, 1992 differs in having a type tA apical archeopyle, and being thin walled. In addition, the blisters of B. argoi are broadly spaced rather than closely adjoined and show evidence of alignment parallel to the cingulum. Batiacasphaera bergenensis sp. nov. differs from Habibacysta tectata Head et al., 1989b in having an apical archeopyle, and septa rather than columellae. Filisphaera filifera Bujak 1984, which has a similar internal wall structure, has a precingular archeopyle and shorter septa that form a microreticulum instead of blisters.
Holotype: Schreck and Matthiessen, 2014, pl.1, figs.1–9.
Type locality: ODP Site 907, eastern Iceland Plateau (69°14.989′N, 12°41.894′W).
Stratigraphic horizon: ODP Hole 907A, 169.10 mbsf; lower Serravallian (upper Middle Miocene), Subchron C5ABn, calibrated age 13.39 Ma.
Stratigraphic occurrence: In Iceland Sea ODP Hole 907A, Batiacasphaera bergenensis sp. nov. ranges from the uppermost Langhian (13.68 Ma) through lower Tortonian (11.09 Ma).
Age: latest Langhian–early Tortonian.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Schreck and Matthiessen, 2014]:
Diagnosis:
A species of Batiacasphaera having a spherical central body, thin solid inner wall layer and thicker outer wall of non-tabular irregular high (up to 5 μm), narrow solid septa which form a continuous tectum of closely adjoining blisters with polygonal to elongate outline.
Archeopyle apical, and operculum free, other tabular features absent.
Description:
Small to medium sized holocavate proximate cyst with a spherical central body, but undulating outline in cross-section (Plate I, 4, 5 and 11). The cyst wall consists of two layers; a thin (b1 μm) pedium that appears solid under light microscope, and a luxuria, which comprises non-tabular, distributed solid septa of uneven height (c. 2–5 μm on individual specimens) that expand distally to create a tectum in the form of numerous closely adjoining blisters. Cysts are rarely crumpled or folded due to the thick wall. Where they branch distally, septa are indented, and sometimes slightly thickened as seen under light microscope. Larger specimens usually have higher septa (Fig. 5), and variation of septa height occurring on the same cyst and indentation at intersections account for the undulating outline of the central body in optical section. Under SEM, individual septa may additionally branch and/or fuse at random height over entire length (Plate I, 15). Spacing between septa varies on individual specimens. The variations in septa height and spacing result in a continuous but irregular tectum comprising densely spaced blisters. The shape of blisters is irregular rounded polygonal to rectangular, sometimes elongated with significant variations in size (Plate I, 9 and 14), and they may appear as a reticulum under light microscope due to ‘LO’ effect (Plate I, 8 and 9).
The distribution pattern of blisters does not reflect any tabulation pattern. This ornament spreads over the entire surface of the cyst without variation, and extends to the archeopyle margins without modification.
The archeopyle is apical with a low to moderately angular principal suture that appears slightly thickened (Plate I, 1, 12 and 16), and lacks accessory sutures. The shape of the archeopyle indicates that it is presumably formed by loss of 3 apical plates. The operculum is free and was not observed on any specimen.
There is no other expression of tabulation.
Dimensions:
Holotype: Central body maximum diameter (without luxuria), 36 μm, maximum septa height, 4 μm.
Range: Central body maximum diameter (without luxuria), 21(30.6)36 μm, maximum septa height, 2(3.5)5 μm. Thirty-five specimens were measured (see also Fig. 5).
Affinities/Discussion:
This species has been assigned to the genus Batiacasphaera due to its spherical central body, low surface ornament, and apical archeopyle presumably consisting of 3 apical plates. It possesses a slightly thickened principal archeopyle suture, which is typical for some Batiacasphaera species. It differs from all other Batiacasphaera species in having a cyst wall composed of a thin pedium that supports a luxuria of solid, high septa which form a tectum rather than two closely appressed wall layers as typical for the genus. In Kallosphaeridium de Coninck 1969 the multiplate apical archeopyle is attached to the sulcus. Blysmatodinium argoi McMinn, 1992 differs in having a type tA apical archeopyle, and being thin walled. In addition, the blisters of B. argoi are broadly spaced rather than closely adjoined and show evidence of alignment parallel to the cingulum. Batiacasphaera bergenensis sp. nov. differs from Habibacysta tectata Head et al., 1989b in having an apical archeopyle, and septa rather than columellae. Filisphaera filifera Bujak 1984, which has a similar internal wall structure, has a precingular archeopyle and shorter septa that form a microreticulum instead of blisters.