Gyroidina, d'Orbigny, 1826

Setoyama, Eiichi & Kaminski, Michael A., 2015, Neogene benthic foraminifera from the southern Bering Sea (IODP Expedition 323), Palaeontologia Electronica (International ed. in English) 76 (4), pp. 1-30 : 18-20

Gyroidina ? sp. A

Figures 7.3a–c, 7.4a–c

Description. Test small, trochospiral, tightly coiled with a flat spiral side and more convex umbilical side, bluntly angled periphery and eight chambers in the final whorl. Umbilicus very small. Chambers increasing in size gradually. Sutures clear, straight, flush, or slightly depressed, radial on the umbilical side. Wall smooth or slightly rough, finely perforated. Aperture a basal slit or a low arch with a lip. It is not clear if there is a bipartitor.

Remarks. This form may be a juvenile of Parrelloides or Hansenisca , which are recorded in this study. The extent of the aperture varies among specimens, but the aperture and the lip do not extend clearly onto the spiral side so that it is not likely that they belong to the genus Cibicidoides . This particular form is found only in two samples.

Figures

FIGURE 7. All scale bars are 100 µm. 1. Quadrimorphina laevigata, 13H-3, 146–148 cm; a. dorsal view; b. ventral view; c. edge view. 2. Oridorsalis umbonatus, 3H-CC; a. dorsal view; b. ventral view; c. edge view. 3. Gyroidina? sp. A, 36H-5, 148–150 cm; a. dorsal view; b. ventral view; c. edge view. 4. Gyroidina? sp. A, 36H-CC; a. dorsal view; b. ventral view; c. edge view. 5. Hansenisca sp. A, 9H-3, 146–148 cm; a. dorsal view; b. ventral view; c. edge view showing a basal slit aperture. 6. Hansenisca sp. A, 16H-3, 146–148 cm; a. dorsal view; b. ventral view; c. edge view showing a low arch aperture. 7. Epelistoma sp. A, 63X-3, 146–148 cm, lateral view. 8. Lenticulina sp. A, 26H-5, 147– 149 cm; a. lateral left view; b. edge view. 9. Lenticulina sp. B, 62X-5, 146–148 cm; a. lateral left view; b. edge view. 10. Hemirobulina sp. A, 9H-5, 146–148 cm; a. lateral left view; b. edge view. 11. Reussoolina apiculata, 28H-CC, lateral view. 12. Lagena cf. Lagena tagusensis, 12H-3, 146–148 cm; a. lateral view; b. apertural view. 13. Lagena striata, 10H-3, 146–148 cm; a. lateral view; b. apertural view. 14. Oolina squamosa, 10H-3, 146–148 cm; a. lateral view; b. apertural view. 15. Glandulina ovula, 36H-5, 148/150 cm, lateral view.