Nannotax Enabling nannofossil research

Description: Coccospheres usually dithecate, Exothecal coccoliths (XCs) highly variable. Endothecal coccoliths are muroliths with 1, 2 or 3 flanges, (the forms with 2 flanges are often placolith-like), these are often differentiated into body coccoliths (BCs), circum-flagellar coccoliths (CFCs) and antapical coccoliths (AACs).

Remarks: About 60 modern species of Syracosphaera are known (Young et al. 2003) and their coccolith morphology is well established. Most Pleistocene specimens of Syracosphaera can be asigned to modrn txa but in older sediemnts the occasional Syracosphaera specimens appear to belong to different species. A few examples are shown below.

Exothecal coccolith structure: As argued by Inouye & Pienaar (1988), Cros (2000) and Young et al. (2004), exothecal coccoliths appear to be modified versions of the endothecal coccoliths, and are composed of the same set of components - rim, radial lath cycle and axial structure. However, the morphology of the coccoliths is highly variable and often radically different to that of the body coccoliths.

LM: Isolated body coccoliths typically show a narrow rim with moderate birefringence and strongly curved isogyres. The central area is weakly birefringent and shows tangential orientation (so blue and yellow sectors show the opposite to normal disposition).

Type species: S. pulchra.

Synonyms: Caneosphaera Gaarder in Gaarder & Heimdal 1977; Deutschlandia Lohmann 1912; Gaarderia Kleijne 1993. NB Caneosphaera and Deutschlandia are usually considered synonyms of Syracosphaera following Jordan & Young (1990). Gaarderia was recombined in Syracosphaera by Young et al. (2003) on the grounds that it showed too few unique features to be regarded as a separate genus.