Pontosphaera trena

Discolithus trenus Kamptner, 1967

In this Pontosphaera species, the walls are relatively high, and the proximal plate is perforated by pores arranged in a single complete concentric cycle, with additional randomly arranged pores in the centre. The distal cover over the proximal plate is low, leading to weaker interference colours in the central area than in the wall in the plan view under XPL. Pontosphaera trena exhibits laevogyre-inclined extinction lines, with a typical extinction angle of about 62° on the distal side, and shows length-fast (−) elongation.

Pontosphaera trena can be distinguished from Pontosphaera sparsiforata by its smaller size, being less than 10.0 μm.

Kamptner, E. 1967. Kalkflagellaten - Skelettreste aus Tiefseeschlamm des Südatlantischen Ozeans. Annalen des Naturhistorischen Museums in Wien. 71: 117-198.

Varol, O. 1989a. Calcareous nannofossil study of the central and western Solomon Islands. In: Vedder, J.G. & Bruns, T.R., (Eds.), Geology and offshore resources of Pacific island arc-Solomon Islands and Bougainville, Papua New Guinea Regions: Houston, Texas, Circum-Pacific Council for Energy and Mineral Resources Earth Sciences Series. 12: 239-268.