Description: Coccolith structure - coccoliths are open tubes with internal septae (walls). The outer tube wall shows hexagonal fabric and the crystallites have
radial c-axes (birefringent in plan view in LM). The fabric of the
septae is not obviously different but they are non-birefringent in plan
view in LM and so the calcite crystallites must have vertical c-axes.

Coccospheres monomorphic, nearly spherical.

Coccolith form - the internal septae define 8-20 pores, tube 10-15 crystallites high, upper surface of coccolith convex; higher in centre than edges. Essentially similar to C. quadriperforatus HOL but larger and with more pores.

Remarks:

Original description:

Size: Liths 3-4 µm long.

Possible life-cycle association: S. schilleri is so similar to the Calcidicus quadriperforatus holococcolith phase that it seems likely that it is a closely related species and so a member of the Calcidiscaceae. This might, however, be a species of Oolithotus or Umbilicosphaera rather than Calcidiscus, so in the absence of direct evidence the species is left in its traditional holococcolith genus Syracolithus.

Synonym:

Holodiscolithus macroporus (Deflandre in Deflandre and Fert, 1954) Roth, 1970 - S. schilleri is sporadically present in Neogene sediments but it is usually identified as H. macroporus, which is probably a junior synonym.