Carlamuelleria tuezueniorum Varol, 2023
In honour of renowned nannofossil specialist Dr Carla Müller, Germany.
A circular to subcircular coccolith comprising a nonbirefringent distal shield, a tube cycle and a vestigial diminutive proximal shield.
Carlamuelleria is a coccolith with a non-birefringent lenticular distal shield made up of between 17 and 45 segments joined along most of their length. The tube cycle is often flush with the distal side of the shield. The combination of the tube cycle and the vestigial diminutive proximal shield creates a brandy goblet-shaped structure in side view.
Optical properties: In plan view, the optical properties of the tube cycle and the shield are aligned in opposite directions. The blue interference patterns on the shields are aligned diagonally in the NW-SE direction on the distal and proximal sides. The oblique inclined extinction lines are dextrogyre on the distal side but laevogyre on the proximal side. The extinction angle assists in the identification of the distal or proximal side.
The presence of an elliptical tube cycle distinguishes subcircular Carlamuelleria karacuhae from other species of Carlamuelleria. The number of segments in their distal shield distinguishes Carlamuelleria bramlettei (<22 segments) from Carlamuelleria tuezueniorum (>23 segments). Fig. 5 in Varol (2023) shows the segment count in a mobile mount for Carlamuelleria bramlettei and Carlamuelleria tuezueniorum from DSDP Site 245A and Site 354.
In the mobile mount, in side view, Carlamuelleria and Davidbukrya are easily differentiated by the presence of a proximal shield (e.g., Carlamuelleria has a vestigial proximal shield, whereas Davidbukrya lacks one). The tube cycle and proximal shield create an X-shaped structure in Noelia and Senelia, but generate a brandy goblet-shaped structure in Carlamuelleria.
Mapping the optical properties of the proximal and distal sides enables Carlamuelleria to be distinguished from Davidbukrya, Noelia and Senelia in plan view. In cross-polarised light with a gypsum plate, the interference colours of the tube cycle are aligned axially in Davidbukrya, Noelia and Senelia but diagonally in Carlamuelleria. Moreover, the blue sectors are aligned in the same direction on the tube cycle and the shield in Davidbukrya, but the blue sectors of the tube cycle and shield are aligned in opposite directions in Carlamuelleria.
In a mobile mount, in side view, Carlamuelleria and Markalius are easily differentiated by the characteristics of their proximal shields; Carlamuelleria has a vestigial proximal shield, and Markalius has a spaced proximal shield with an acute inclination angle.
Carlamuelleria can be distinguished from Markalius in plan view using optical properties. In cross-polarised light with a gypsum plate, the blue sectors are aligned in opposite directions in the tube cycle and on the shield in Carlamuelleria and Markalius. The interference colours of the tube cycle are aligned axially in Markalius but diagonally in Carlamuelleria. It is possible to obtain additional evidence when identifying Markalius in bright-field and phase-contrast illumination by detecting the proximal shield with careful focus (Plate 1, figs. 4,8,16,20 in Varol, 2023).
Varol, O. 2023. New paleocene calcareous nannofossils: Carlamuelleria, Davidbukrya, Mauriceblackia, Noelia and Senelia. Marine Micropaleontology. 180: 1-41.