Apertural features and surface texture of upper Paleogene biserial planktonic foraminifers: links between Chiloguembelina and Streptochilus.

Several upper Paleogene species of Chiloguembelina have an internal apertural plate that is very similar to the internal plate typical of the Neogene genus Streptochilus. The type species of Chiloguembelina, C. midwayensis midwayensis (Cushman), however, lacks any internal apertural structure or modifications. Therefore, the following 'Chiloguembelina', which have an internal plate, are assigned to Streptochilus: S. cubensis (Palmer), S. martini (Pijpers) and S. sp.aff. S. martini. -Authors