Abstract

Exceptionally large quantities of outstandingly well-preserved, free specimens of larger foraminifera from late Miocene sediments of the Dominican Republic invite an analysis of their structure in detail. The structures of the porcelaneous larger foraminifera reveal that most of them are not candidates for a direct ancestry of the species living today in the Caribbean. Although the late Miocene period has produced Caribbean endemists, in particular within the agglutinated group of the textulariellids and the lamellar-perforate group of the amphisteginids, the porcelaneous archaiasines and soritines are more closely related to the early Miocene forms of the Neotethys than to the Recent Caribbean endemists. These relationships are derived from their relative structural similarity and call for the proposition of appropriate additional taxa on the generic and specific levels. Miocene Miarchaias new genus develops several centimeters large, cyclical agamonts with meandropsinid structures covering the lateral surface of the disc (M. meander new species) whereas species of smaller shell size do not have cyclical generations (M. modestus new species). On the other hand, populations of cyclical schizonts and/or gamonts exhibit structures similar to the Recent, spiral Androsina: Androsinopsis radians new genus and species. The other new taxa erected here, Annulosorites spiralis new genus and species and Cyclorbiculina miocaenica new species, reflect differences in the apertural face and the respective arrangement of radial partitions as used to differentiate Recent Sorites from Amphisorus. Specimens to be attributed to the genera Cycloputeolina and Parasorites are present in the late Miocene of the Dominican Republic. They exhibit an exoskeleton in contrast to true soritids, and will need an eventual worldwide revision on the species level.

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