Belongs within: Rotaliida.
The Chilostomellidae are a group of trochospiral Foraminifera known from the Jurassic to the present day (Loeblich & Tappan 1964).
Characters (from Loeblich & Tappan 1964, as Chilostomellinae): Test trochospiral, with few chambers to whorl, planispiral and involute; aperture interiomarginal on umbilical side.
<==Chilostomellidae [Chilostomellinae]
| i. s.: Quadrimorphina Finlay 1939 [=Gyromorphina Marie 1941; incl. Pallaimorphina Tappan 1957] LT64
| |–*Q. allomorphinoides (Reuss 1860) [=Valvulina allomorphinoides] LT64
| `–Q. ruckerae (Tappan 1957) [=*Pallaimorphina ruckerae] LT64
|–Allomorphina Reuss in Cžjžek 1849 C40, LT64 [Allomorphininae]
| |–*A. trigona Reuss 1850 C40
| |–A. cretacea M08
| |–A. pacifica JW99
| `–A. paleocenica QS03
`–+–Allomorphinella Cushman 1927 C04
| `–*A. contraria (Reuss 1851) [=Allomorphina contraria] LT64
`–+–Chilostomelloides Cushman 1926 C40
| `–*C. oviformis (Sherborn & Chapman 1886) [=Lagena (Obliquina) oviformis] C40
`–Chilostomella Reuss 1850 C40
|–*C. ovoidea Reuss 1850 C40
`–C. oolina Schwager 1878 H03
*Type species of generic name indicated
REFERENCES
[C40] Cushman, J. A. 1940. Foraminifera: Their classification and economic use 3rd 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. 2. The Geological Society of America and The University of Kansas Press.
[M08] McMillan, I. K. 2008. Reappraisal of foraminiferal assemblages of the Santonia-Campanian Mzamba Formation type section, and their correlation with the stratigraphic succession of the KwaZulu Basin. African Natural History 4: 25–34.
[QS03] Quattrocchio, M. E., & W. A. S. Sarjeant. 2003. Dinoflagellates from the Chorrillo Chico Formation (Paleocene) of southern Chile. Ameghiniana 40 (2): 129–153.