Denisea magna

Set number: 531

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Denisea magna, Late Paleocene, DSDP Leg 39, Sites 354, Ceará Rise, North Atlantic Ocean

Set number: 530

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Denisea magna, Middle Paleocene, DSDP Leg 25, Site 245, Mozambique Channel (Davie Ridge), Indian Ocean

Set number: 529

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Denisea magna, Late Paleocene, DSDP Leg 25, Site 245, Mozambique Channel (Davie Ridge), Indian Ocean

Set number: 527

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10µm

Denisea magna, Late Paleocene, DSDP Leg 25, Site 245, Mozambique Channel (Davie Ridge), Indian Ocean

Set number: 528

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10µm

Denisea magna, Middle Paleocene, DSDP Leg 25, Site 245, Mozambique Channel (Davie Ridge), Indian Ocean

Final Epithet

Denisea magna Varol, 2022

Basionym

Denisea magna Varol, 2022

Etymology

From Latin magna, meaning " very large", it refers to its large and vacant central area.

Dimensions Of Holotype

Maximum diameter: 10.30 μm, the diameter of the central area: 4.96 μm, the width of the pelaga: 2.67 μm; thickness: 3.87 μm.

Inclination angles of holotype: Distal shield: 75.0°; proximal shield: 62.3°; sutures between the shields: 74.1°; suture between the tube cycle and the shields: 32.2°.

Description

Large (9.0–12.0 μm) Denisea species have a birefringent tube cycle, two shields, and a wide vacant central area. The diameter of the central area is greater than or equal to the width of the pelaga but not twice as much. The separation of the tube cycle and shields is more clearly visible in bright-field and phase-contrast illuminations.

Remarks

Denisea magna, Denisea constricta, and Denisea polymegalo have similar sizes (9.0–12.0 μm), but their central area sizes distinguish them. The central area is narrower than the width of the pelaga in Denisea constricta. The diameter of the central area is at least twice the width of the pelaga in Denisea polymegalo. In Denisea magna, the central area is larger than the width of the pelaga but not twice as much. Denisea magna differs from Denisea aliquanta, Denisea foramena, and Denisea subpertusa by being larger than 9.0 μm. The overall size of Denisea aliquanta, Denisea foramena, and Denisea subpertusa ranges between 5.0 and 9.0 μm.

References

Varol, O. 2022. Denisea, a new genus of Paleocene calcareous nannofossils. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 304/2 (2022): 159-186.