Watznaueria cauveryensis
Set number: 3246
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10µm
Watznaueria cauveryensis Varol, in prep.
Large, subcircular species (10.0–13.0 µm) of Watznaueria, characterised by a broad inner tube cycle that completely closes the central area. The narrow outer tube cycle is clearly discernible under phase-contrast and bright-field illumination. The width of the tube cycles exceeds that of the shields.
Named after the type locality, Cauvery Basin, India
In plan view under cross-polarised light, the shields exhibit first-order yellowish-white interference colours, while the inner tube cycle shows first-order white interference colours. The outer tube cycle presents first-order whitish-yellow interference colours. All structures display inclined extinction lines and have a length-fast (–) elongation. In distal view, the extinction angles are approximately 73° in the shields and about 60° in the tube cycles. The locking cycle exhibits interference colours, producing a transitional boundary between the tube cycle and shield, but the variation in the orientation of extinction lines between the tube cycles and the shield facilitates recognition of a narrow outer tube cycle, complementing observations under phase-contrast and bright-field illumination.
Watznaueria cauveryensis is distinguished from subcircular Watznaueria angustoralis by its larger size (>10.0 µm). In Watznaueria cauveryensis, the outer tube cycle displays first-order yellow interference colours, whereas in Watznaueria angustoralis it exhibits first-order white interference colours. Extinction angles are otherwise similar in both species.
Watznaueria cauveryensis further differs from Watznaueria paenepelagica and Watznaueria deflandrei in its subcircular rather than elliptical outline, larger size (>10.0 µm), and broader central area relative to shield width. In addition, extinction angles can be measured in the inner tube cycles of Watznaueria cauveryensis, whereas they cannot be directly measured in Watznaueria paenepelagica and Watznaueria deflandrei due to the oblique orientation of their constituent elements.
Lauer, G. 1972. Nannofossilen aus dem Wienerwald, In: Grün, Walter, et. al. Studien in der Unterkreide des Wienerwaldes: [Austria]. Jahrbuch der Geologischen Bundesanstalt, 115: 103–186.
Noël, D. 1965. Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Essai de classification des coccolithes fossiles. Éditions du Centre National de la Recherche Scientifique, Paris. 1-129.
Reinhardt, P. 1964. Einige Kalkflagellaten-Gattungen (Coccolithophoriden, Coccolithineen) aus dem Mesozoikum Deutschlands. - Monatsberichteder Deutschen Akademieder Wissenschaftenzu Berlin. 6: 749-759.
Reinhardt, P. 1971. Synopsis der Gattungen und Arten der mesozoischen Coccolithen und anderer kalkiger Nannofossilien. Teil III. – Freiberger Forschungshefte. C267: 19–41.
Stover, L. E. 1966. Cretaceous coccoliths and associated nannofossils from France and the Netherlands. Micropaleontology 12(2): 133-167.