First report of the Uvigerinids of the Central Equatorial Indian Ocean

The Central Equatorial Indian Ocean (CEIO) is known for its cross-basin exchange since it is influenced by both southwest and northeast monsoon. The present investigation is the first report of the Uvigerinids of CEIO. Here, we document the complex morpho diversity of Uvigerinids and propose a classification based on surface ultrastructure. The twenty seven Uvigerinid species were recorded through the present study and sixteen of them are reported for the first time from the CEIO. The recorded new species are Uvigerina rustica, U. ampullacea aff. auberiana, U. farinosa, U. mantaensis, Siphouvigerina ampullacea aff. aculeata, Siphouvigerina pseudoampullacea, U. lappa, Uvigerina aff. mexicana, U. macrocarinata, U. tumeyensis, U. cubana, U. cocoaensis, U. continuosa, U. flintii, U. semiornata urnula, Hopkinsina shinboi. Based on the various morpho classifications available for Uvigerinids from the World Oceans, we propose to classify the recorded Uvigerinids into hispid-spinose, spinose-pustulous, spinose-costate, serrate-costate, platy-costate, and miscellaneous species. The distribution pattern of Uvigerinids in the study area suggests the CEIO exhibits moderate to high productivity, upwelling and is significantly influenced by glacial-interglacial cycles. This preliminary investigation suggests that CEIO can be a unique area to investigate the evolutionary trajectory of Uvigerinids from the Tertiary period to Recent times.