Cephalogullmi acaudata gen.nov., sp.nov. (Rhizaria, Foraminifera) - a monothalamous foraminifera from the Sea of Japan
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Abstract
We describe anew species and genus of soft-walled monothalamous foraminifera from the Sea of Japan. Material was collected in the area of the Primorsky shelf, during cruise 64 of the R/V "AkademicOparin" (June 17 –July 08 2021). Bottom sediments were sampled at 17 stations in the depth range 0.3 to 86 m. The species described here was found at depths 13 and 86 m. The elongate organic-walled test of Cephalogullmia caudata sp.nov. has an inflated anterior (apertural) part, which gradually narrows towards the adaperturalend. The length varies from 550 to 1180 µm, the width at the widest part (the “head”) from 40 to 135 μm and the narrowest part from about 10 to 20 μm. A single apertural structure (diameter 10-28 µm) is located at the widest end of the shell. The apertural structure is slightly elevated, in some specimens resembling a nipple. The nucleus is visible only in some specimens; its dimension is about 16x12 µm to30x15 μm. The comparative analysis has shown that the new genus Cephalogullmia differs from Micrometula Nyholm, 1952 in the shape of the test, which has more rounded and inflated apertural end, compared to the slender conical test of Micrometula. The new genus differs from Cylindrogullmia Nyholm, 1974 in having a more or less tapered test, rather than one that is cylindrical. It also differs from another elongate organic-walled monothalamid, Bowseria Sinniger et al., 2008, in having a darker protoplasm and a narrowed (tail-shaped) distal end.