Senelia plevrotos Varol, 2023
In honour of the late geologist Dr Mustafa Şenel, Ankara, Turkey. Mustafa’s geological and stratigraphical work on the Taurus Mountains contributed significantly to the compilation and publication of Turkey’s 1/100,000, 1/250,000, and 1/500,000-scale geological maps at the MTA Geological Studies Department.
A circular coccolith comprising a non-birefringent distal shield, a broad tube cycle without distal protrusion, and an appressed proximal shield.
The number of segments that construct the distal shield is between 26 and 40. The tube cycle and proximal shield combination create an asymmetrical X-shape structure in the side view (Plate 16, Figs. 3, 7; Plate 17, Figs. 2, 6 in Varol, 2023). The broad tube cycle is flush with the distal shield. The narrowest point of the central area lies at the boundary between the tube cycle and its proximal shield, which corresponds to the sharp tapering inner end of the distal shield.
Senelia includes two new species in the original publication, Senelia plevrotos and Senelia perifanos. Senelia plevrotos and Senelia perifanos differ by the shape of their tube cycle and the distal shield in their side view. The distal shield has pointed ends in Senelia perifanos and rounded ends in Senelia plevrotos. The width of the X-shape structure is much greater than its height in Senelia perifanos. The smooth tube cycle’s diameter is often two times wider than the width of the shield in Senelia perifanos; this can be seen in both the side view (Plate 16, Fig. 3,7 in Varol, 2023) and plan view (Plate 16, Fig. 14 in Varol, 2023). In Senelia plevrotos, the periphery of the tube cycle is serrated, and its diameter is about equal to the width of the shield.
Optical properties: In cross-polarised light, identifying the curved direction of the inclined extinction lines (symmetrical) is challenging. Senelia displays laevogyre extinction lines distally (Plate 17, Figs. 10,14 in Varol, 2023) and dextrogyre extinction lines proximally (Plate 17, Figs. 11,15 in Varol, 2023). With the gypsum plate inserted, the blue sectors correspond to the horizontal axis on the distal side (Plate 17, Fig. 14 in Varol, 2023). In contrast, the blue sectors correspond to the vertical axis on the proximal side (Plate 17, Fig. 15 in Varol, 2023).
Senelia differs from Noelia and Mauriceblackia by lacking a distally protruding tube cycle above the distal shield. Senelia is distinguished from Davidbukrya and Carlamuelleria by having an appressed proximal shield. Davidbukrya has no proximal shield, and Carlamuelleria has a vestigial, diminutive proximal shield.
The spaced proximal shield is present in Coccolithus formosus (Plate 2, Figs. 2, 6 in Varol, 2023), Markalius astroporus (Plate 1, Figs. 15,19 in Varol, 2023) and Mauriceblackia media (Plate 2, Figs. 14,18 in Varol, 2023). In Senelia, the appressed proximal shield is contracted and bound to the inner perimeter of the distal shield
Varol, O. 2023. New paleocene calcareous nannofossils: Carlamuelleria, Davidbukrya, Mauriceblackia, Noelia and Senelia. Marine Micropaleontology. 180: 1-41.