Catalog - Huberella

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Huberella

Citation: Huberella Georgescu 2007

Diagnosis. Test biserial throughout; last-formed chambers with test wall flexure resulting in projections attached to the previous chamber in the row; no accessory apertures are present along the zigzag suture; chamber surface finely costate; test wall calcareous, micrcroperforate.
Description. Test biserial throughout. Proloculus is smaller than the second chamber. Chambers are subglobular to reniform in shape, tilted to the axis of growth at least in the adult portion of the test. Chamber projections attached to the previously formed ones in the row are present in the morphologically advanced tests. Sutures are distinct, depressed, straight to curved, oblique to the test axis of growth. Periphery broadly rounded, without peripheral structures. Aperture is situated at the base of the last-formed chamber and is bordered by two symmetrical periapertural flanges. No accessory apertures are present along the zigzag suture. Chamber surface is ornamented with fine, closely spaced and often discontinuous costae. Test wall is calcareous, hyaline, microperforate.

Remarks. Huberella nov.gen. differs from Pseudoguembelina in lacking accessory apertures along the zigzag sutures. The general appearance of accessory apertures along the zigzag suture is given by the infolding of the test wall. It differs from Heterohelix by the presence of chamber projections attached to the previous chambers of the row. Huberella is a genus that apparently documents the first attempt of the Cretaceous serial planktonic foraminifera to develop accessory apertures along the zigzag suture. Such successful process happened in the late Campanian, within the Heterohelix labellosa Nederbragt 1991-Pseudoguembelina costulata (Cushman) 1938 lineage. Accordingly, no phylogenetic relationship between Huberella nov.gen. (Turonian) and the “true” Pseudoguembelina costulata-P. excolata group of species of the late Campanian- Maastrichtian do exist. This is strongly supported by the differences in ornamentation, which consists of fine, discontinuous costae in Huberella and strong, continuous costae in the typical Pseudoguembelina (pl. 1, figs. 2-3). The latest Campanian- Maastrichtian pseduoguembelinids with finer costae present well-developed apertures along the zigzag sutures (e.g., Pseudoguembelina costellifera, P. hariaensis Nederbragt,1991, P. kempensis and P. palpebra) (pl. 1, figs. 4-7) first occur in the latest Campanian (lower part of the Gansserina gansseri Biozone). There is a gap of approximately 18.5 million years between the last documented stratigraphic occurrence of Huberella and first evolutionary occurrence of the fine costate Pseudoguembelina species (fig. 2). Therefore, the relative similarities between Huberella and the finely costate Pseudoguembelina species are the result of convergent evolution.

Phylogenetic relationships. Huberella evolved from Heterohelix moremani (Cushman) 1938. This is documented by the existence of an evolutionary continuum between Heterohelix moremani, Huberella praehuberi and Huberella huberi. Huberella shares with its Heterohelix moremani ancestor the test symmetry in edge view, similar earlier portions of the tests, similar and symmetrically developed periapertural flanges and microperforate test wall. Its evolution was realized through development of costate ornamentation and gradual development of chamber projections. There is also a gradual reduction of the number of chambers within this lineage: Heterohelix moremani (17-21) Huberella praehuberi (15-17) Huberella huberi (13-14). Huberella became extinct in the proximity of the Turonian/Coniacian boundary leaving no descendants.

Species included: Huberella huberi n.sp. Huberella praehuberi n.sp.

References:

Georgescu, M. D. (2007a). A new planktonic heterohelicid foraminiferal genus from the Upper Cretaceous (Turonian). Micropaleontology. 53: 212-220. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Huberella Georgescu 2007

Huberella

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			Huberella huberi Georgescu 2007 = Huberella huberi
			Huberella praehuberi Georgescu 2007 = Huberella praehuberi
			Huberella yucatanensis Georgescu 2011, in Georgescu et al. 2011