A collection of juvenile holoplanktic Mollusca (Gastropoda, Pterotracheoidea and Pteropoda) from the Miocene of Trinidad, with the introduction of the new genus Chriskingia

Holoplanktic gastropods isolated from Miocene rock samples collected for foraminifer research at two localities in central Trinidad consist predominantly of juvenile specimens. Nine samples from the Nollis Tunnel section near Tabaquite, from the Langhian (N8 Zone), yielded 12 species (three Pterotracheoidea, eight Pteropoda, one unidentified). From nine samples of the Brasso gorge section at Brasso Village, from the Serravallian (Zones N11-12), four species (all Pteropoda) were isolated, one of which was not represented in the Nollis Tunnel section. Most species could only be identified to genus level. A new genus in the Atlantidae, Chriskingia gen. nov., is introduced. The pterotracheid genus Firoloida Lesueur, 1817 is recorded for the first time from Miocene deposits. The pteropods Limacina valvatina (Reuss, 1867) and Creseis roesti Janssen, in Cahuzac & Janssen, 2010 represent new species for the American Miocene. The numerical occurrence of the species demonstrates considerable differences that are discussed in the context of the oxygen minimum zone occurring in these sections, as discussed by Wilson & McLean (in press).