Abstract
A new benthic foraminifer, Helenina davescottensis nov. sp., is described from an oligohaline carbonate marsh (palustrine environment) located in a sinkhole on Grand Bahama Island, The Bahamas. The uppermost stratigraphy in the sinkhole is characterized by up to 260 cm of peat, which is overlain by 5–10 cm of carbonate sediment that contain H. davescottensis . Ontogenetic variability is illustrated with a full sequence of individuals from two chambers (proloculus + first chamber) through eight chambers. Chamber arrangement is planispiral evolute in juveniles that have fewer than three chambers, but arrangement changes to trochospiral evolute when the fourth chamber is added. Adults rarely exceeded 6–7 chambers and were never observed with more than 8 chambers. Supplementary apertures are common and diverse, and multi-chambered individuals typically achieve 100–200 μm in diameter. Helenina davescottensis was found co-occurring with other low-oligohaline microfossils ( Jadammina macrescens , testate amoebae, charophytes, and hydrobiid gastropods), but not other common euryhaline hyaline foraminifera (e.g., H. anderseni , Ammonia tepida ). Given the sinkhole stratigraphy, perhaps H. davescottensis was an early colonizer of a recently generated palustrine environment.
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