Hansenisca sp. A

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 : 20

Hansenisca sp. A

Figures 7.5a–c, 7.6a–c

Description. Test of medium size, trochospiral, spiral side evolute and flat to slightly elevated, umbilical side involute and elevated, with an small open umbilicus with subangular shoulder, with nine to ten chambers in the final whorl. Periphery more angular than rounded. Chambers increasing in size gradually. Sutures flush or very slightly depressed, curved backwards on the spiral side, radial and straight on the umbilical side. Wall calcareous, very finely perforate, smooth. Aperture an interiomarginal small pore-like opening placed between the umbilicus and the periphery with a narrow lip. A second aperture is present at the umbilicus with a flap.

Remarks. This form resembles species of Gyroidina , such as Gyroidina soldani ( d’Orbigny, 1826) , but differs by possessing a second aperture at the umbilicus. The size of the umbilicus varies greatly, and it is almost closed in some specimens. A very similar form was reported as Gyroidinoides sp. A from the Izu-Bonin Arc (ODP Legs 125 and 126) by Kaiho (1992, pl. 8, fig. 8).

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.