New genera and species of monothalamous Foraminifera from Balaclava and Kazach’ya Bays (Crimean Peninsula, Black Sea)

摘要

We describe two new genera and species of monothalamous Foraminifera from a coastal site in Balaclava Bay, Crimea. Nellya rugosa gen. and sp. nov. has an elongate, approximately oval test, 120–360 μm long, somewhat resembling a rice grain and with a single nipple-like apertural structure located at the distal end, which is often rather truncated. The wall is whitish, opaque, somewhat flexible and composed of jumbled mineral grains, mostly <10 μm in size, overlying an inner organic layer. Cedhagenia saltatus gen. and sp. nov. has an approximately lenticular test, 150–300 μm long, with a single aperture usually associated with a short, delicate, slightly flared extension of test. The wall is whitish, flexible, translucent with shiny highlights, and composed of a thin layer of plate-like mineral grains, mostly <5 μm in size, overlying an inner organic layer. In both N. rugosa and C. saltatus, the cytoplasm is finely granular, without stercomata. A third species, identified as Vellaria pellucidus Gooday and Fernando 1992 and closely resembling the type material of this species from the Vellar Estuary (India), occurs occasionally in our Balaclava Bay material. Samples from another Crimean Bay (Kazach’ya) yielded an undescribed species of Psammophaga that is most similar to a species from Southampton (UK). The agglutinated wall encloses a cell body that is packed with mineral grains. Analysis of the SSU rDNA sequences obtained from these four species confirmed the position of Psammophaga and Vellaria. Nellya is shown to be a sister group to Vellaria + Psammophaga clade but its position is not well resolved. Cedhagenia belongs to a very different clade of monothalamous foraminiferans, which includes also Ovammina and Cribrothalammina.