Gyroidina

Gyroidina orbicularis, from here.

Belongs within: Rotaliida.

Gyroidina is a genus of trochoid Foraminifera known from the Lower Cretaceous to the present (Cushman 1940).

Characters (from Cushman 1940): Test trochoid, ventral side usually convex, umbilicus small and deep, spiral suture with depressed channel; wall calcareous, finely perforate; aperture a low arched opening on ventral side toward umbilical area.

Gyroidina d’Orbigny 1826 C40
    |--*G. orbicularis d’Orbigny 1826 C40
    |--G. altiformis Stewart & Stewart 1930 [=G. soldanii var. altiformis] H03
    |--G. broeckiana JW99
    |--G. depressa C40
    |--G. girardana C40
    |--G. komatsui Aoki 1964 [incl. Gyrodinoides shinjiensis Nomura 1986] H03
    |--G. neosoldanii H90
    |--G. nitida JW99
    |--G. profunda Aoki 1964 H03
    `--G. soldanii LT64

*Type species of generic name indicated

REFERENCES

[C40] Cushman, J. A. 1940. Foraminifera: Their classification and economic use 3^rd ed) Harvard University Press: Cambridge (Massachusetts).

[H03] Hanagata, S. 2003. Miocene-Pliocene Foraminifera from the Niigata oil-fields region, northeastern Japan. Micropaleontology 49 (4): 293–340.

[JW99] Jian, Z.-M., L.-J. Wang, M. Kienast, M. Sarnthein, W. Kuhnt, H.-L. Lin & P.-X. Wang. 1999. Benthic foraminiferal paleoceanography of the South China Sea over the last 40,000 years. Marine Geology 156: 159–186.

[LT64] Loeblich, A. R., Jr & H. Tappan. 1964. Sarcodina: chiefly “thecamoebians” and Foraminiferida. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt C. Protista 2 vol. 1. The Geological Society of America and The University of Kansas Press.