Original Description Diagnosis.– Tests low trochospiral, with radially elongate chambers in the adult; elongation axis is perpendicular, rarely backwards tilted; last formed chambers in the evolved species with a bulbous projection at the distal end; earlier species have pustulose test surface, evolved ones can be smooth.
Description.– Tests low trochospiral, with chambers that increase gradually in size. Chambers of the juvenile stage globular; last formed ones radially elongated, subcylindrical or dorso-ventrally compressed in edge view and with the elongation axis perpendicular or at a high angle (> 85°) to the previous whorl. Sutures are distinct and depressed, often limbate due to the lack of chamber overlapping. Periphery is rounded and simple. Aperture is a low to medium high arch, umbilical-peripheral in position and bordered by an imperforate lip; relict periapertural structures and apertures can occur in the umbilicus. Chamber surface of the earlier species ornamented with dome-like scattered pustules, denser on the earlier chambers; evolved species are mostly smooth. Test wall calcitic, hyaline and perforate; pores show gradual increase in size along the lineage. Size: Etymology: Genus named in honor of Dr Emile A. Pes- sagno Jr. (University of Texas) for his studies on the Creta- ceous planktic foraminifera of USA, Mexico and Puerto Rico. Extra details from original publication Remarks.– Pessagnoina differs from Clavihedbergella by the pustulose chamber surface in the primitive species and radially elongate last formed chambers with bulbous distal projections in the evolved ones. It differs from Pseudoclavihedbergella by the more elongate chambers, which have a bulbous distal projection in the evolved species and the absence of the peripheral band with lower pore density and smaller pores that occasionally occurs in the latter. The test wall is simple, contrasting to the cancellate wall of the upper Turonian tests with radially elongate chambers. Eohastigerinella lineage of the Santonian is a homeomorph of Pessagnoina; the two lineages document the iterative pattern in developing radially elongate chambers with bulbous projections in the upper Cenomanian (i.e., Pessagnoina) and Santonian (i.e., Eohastigerinella). Pessagnoina differs from Eohastigerinella by being trochospiral, in contrast to the latter that has a clear trend to develop planispiral tests in the evolved species.
Hastigerinella simplex – Morrow, 1934, p. 198, pl. 30, fig. 6;
Hastigerinella moremani – Cushman, 1931, p. 86, pl. 11, figs 1-3.
Stratigraphical range.– Upper Cenomanian-lowermost Turonian (from the R. cushmani Biozone to W. archaeocretacea Biozone). Geographic distribution.– USA (Georgia, Kansas, Texas, Washington State, Wyoming), Canada (Manitoba and southern Saskatchewan) and northern Africa (Egypt). Editors' Notes
Georgescu, M. D. (2009d). Upper Albian-lower Turonian non-schackoinid planktic foraminifera with elongate chambers: morphology reevaluation, taxonomy and evolutionary classification. Revista Española de Micropaleontología. 41: 255-293. gsVO
Pessagnoina compiled by the pforams@mikrotax project teamviewed: 6-2-2023