Species included: IS: D. cretacea (d’Orbigny 1840) (Plate 12, Figures 1–10) and FDS: D. subplana (Korchagin 2011).

Diagnosis: Directional lineage with chamber ornamented with dome–like and conical pustules; periphery simple in the IS and with imperforate peripheral band throughout the final whorl in the FDS; aperture umbilical in the IS and extraumbilical– peripheral in the FDS.

Description: Test is low trochospiral and consists of subglobular to globular chambers that increase gradually in size. Sutures are distinct and depressed and less visible between the earlier chambers due to the addition of successive layers of calcite. Test shape is asymmetrical, with the spiral side slightly convex and the umbilical side slightly concave; periphery is rounded and simple in the IS and with imperforate peripheral band on all the chambers of the final whorl in the FDS. Aperture is medium high arch in umbilical position in the IS and equatorial–peripheral in the FDS; aperture is bordered by a perforate porticus in the IS and relict periapertural structures occur in the umbilical region. Chamber surface is ornamented with dense dome–like and conical pustules, equally developed on all the chambers in the IS and are more prominent on the earlier ones in FDS. Test wall is calcitic, hyaline, simple and perforate; pores are circular and with a diameter of 0.0012–0.0020 mm.

Remarks: Dorbignya is a directional lineage characterized by rapid evolution of the peripheral imperforate band from the IS to FDS and aperture migration from umbilical to peripheral position. It differs from Liuenella, Allotheca and Vanhintella mainly by not evolving planispiral tests and having the aperture covered by one perforate porticus rather than imperforate lip; the aperture is situated in the umbilical position in the IS of Dorbignya rather than equatorial–peripheral as it is in the IS of the other three lineages. Fissoarchaeoglobigerina was described by Abdel–Kireem (1978) based on the occurrence of secondary sutural openings on the dorsal side; it appears evident from the illustrations of this genus that the sutural openings are the result of diagenesis and therefore Fissoarchaeoglobigerina is unusable.

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