Catalog - Hendersonia

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Hendersonia

Citation: Hendersonia Georgescu&Abramovich 2008

Type species: Guembelina carinata Cushman, 1938

Type age (chronostrat): Upper Santonian-Campanian (from the upper part of the Dicarinella asymetrica Biozone throughout Radotruncana calcarata Biozone)

Type locality: USA (Texas, Alabama, Mississippi, New Jersey), Africa (Nigeria, Tunisia), Gulf of Mexico (Yucatan outer shelf), South Atlantic Ocean (Falkland Plateau, Rio Grande Rise and São Paolo Plateau).

Diagnosis.– Heterohelicidae with test wall flexure on the lateral sides of the test, resulting in carinate appearance.

Description.– Test is biserial throughout. Chambers are globular to subrectangular in lateral view, increasing gradually and moderately in size as added. Sutures are distinct and depressed, straight to slightly oblique to the test axis of growth. Periphery is subacute due to the development of a test wall flexure, which results in the duplication of the test wall in the periphery region. Aperture is arch-shaped, situated at the base of the last formed chamber. Two small and symmetrical periapertural flanges, rimmed or not, border the aperture on the lateral sides. Apical part can be smooth. Pustulose periapertural area is present above the aperture. Chamber surface ornamented with costae, which can be parallel to the periphery, longitudi- nal or oblique to the test axis of growth. Ornamentation thickenings can be present on the earlier chambers in the proximity of the central ‘zigzag’ suture. Test wall calcareous, hyaline perforate; pores can be simple, or situated in the center of a crater-like structure in the evolved species.

Genus named after Dr Charles M. Henderson (University of Calgary) in appreciation for his outstanding contributions in paleontology and biostratigraphy.

Remarks.– Hendersonia nov. gen. is characterized by the development of the test wall flexure in the periphery area. Another species with peripheral structures of the Upper Cretaceous (upper Campanian-Maastrichtian) is Gublerina rajagopalani Govindan, 1972. It was described by Govindan (1972, p. 170) as having the test periphery “… ornamented with thick, strongly raised, longitudinal costae.” Nederbragt (1991) re-evaluated the morphology of this species and considered the “Periphery of early part of test acute to keeled, becoming more rounded in the adult chambers.” (Nederbragt, 1991, p. 348). Examination of well preserved material from DSDP Site 356 (São Paolo Plateau, South Atlantic Ocean), DSDP Site 357 (Rio Grande Rise, South Atlantic Ocean) and ODP Holes 761B and 762C (Exmouth Plateau, East Indian Ocean) confirmed the original description by Govindan, the keeled appearance of the earlier portion of the test being given by the development of thick costae. Accordingly, Gublerina rajagopalani appears phylogenetically unrelated to any species of Hendersonia, in which the subacute test periphery is the result of the development of a test wall flexure.

Species included.– Gümbelina carinata Cushman, 1938 (p. 18, pl. 3, fig. 10); Hendersonia hendersoni nov. sp.; Hendersonia jerseyensis n. sp.
Phylogenetic relationships.– Hendersonia nov. gen. evolved from the Heterohelix planata (Cushman, 1938) group of species and is the ancestor of Paraspiroplecta nov. gen. (Fig. 4).

Georgescu and Abramovich (2008b) described the new genus Hendersonia, and two new species of Hendersonia, but it was later discovered that the name was already occupied by a gastropod genus, so it was renamed Hendersonites (Georgescu and Abramovich 2009b)

References:

Georgescu, M. D. & Abramovich, S. (2008b). Taxonomic revision and phylogenetic classification of the Late Cretaceous (upper Santonian-Maastrichtian) serial planktonic foraminifera (Familiy Heterohelicidae Cushman, 1927) with peripheral test wall flexure. Revista Española de Micropaleontología. 40: 97-114. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Hendersonia Georgescu&Abramovich 2008

Hendersonia

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			Hendersonia hendersoni Georgescu&Abramovich 2008
			Hendersonia jerseyensis Georgescu&Abramovich 2008