Sphenolithus philippinensis

Sphenolithus philippinensis Varol, in prep.

After the Philippines, where I first noted this species.

Medium to large size (>5.0µm), elongated cylindrical species of Sphenolithus Deflandre in Grassé, 1952 having segments arranged in three cycles. The cylindrical proximal cycle predominates the low lateral cycle and the diminutive biconical clustered apical spine. In cross-polarised light, the apical spine is extinct (dim) at 0° and shows maximum birefringence at 45°.

In the axial section, the inner ends of the segments in the proximal cycle joined most of their length along the longitudinal axis but not joined nearer the proximal end thus creating a shallow conical proximal cavity.

Sphenolithus philippinensis is easy to identify from Sphenolithus disbelemnos Fornaciari & Rio, 1996 by being larger and having a biconical clustered apical spine whereas the latter has a bouquet shape clustered apical cycle.

Sphenolithus philippinensis differ from Sphenolithus quasibelemnos Varol, in prep. by being larger and cylindrical whereas the latter has a triangular shape in the axial section.

Deflandre, G., 1952. Classe des Coccolithophoridés. (Coccolithophoridae. Lohmann, 1902). In: Grassé, P. P. (ed.), Traité de Zoologie. Masson, Paris 439-470.

Fornaciari, E., Rio, D., 1996. Latest Oligocene to early Middle Miocene quantitative calcareous nannofossil biostratigraphy in the Mediterranean region. Micropaleontology 42(1), 1-37