"Blow suggested that Biglobigerinella kerisensis Suleymanov (1966) might be a senior synonym of P. sharkriverensis. Biglobigerinella kerisensis was described from the upper Eocene of Kizil Kum, central Asia of the former Soviet Union. Scanning electron micrographs of the holotype of this species (Pl.14.4, Figs. 13-15) show a deformed specimen with an asymmetrical ultimate chamber which extends over and obscures the umbilical area of one side. Although the specimen appears to be planispiral, it is difficult to make a meaningful morphological comparison with P. sharkriverensis without additional specimens"
Olsson, R.K. & Hemleben, C. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Globanomalina, Planoglobanomalina n. gen and Pseudohastigerina. <em>In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. Allen Press, Lawrence, Kansas.</em> 413-432.