Catalog - Globorotalia (Clavatorella) prolata

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Other pages this level: G. (Clavatorella) oveyi, G. (Clavatorella) prolata

Globorotalia (Clavatorella) prolata

Citation: Globorotalia (Clavatorella) prolata Belford 1984

Type specimens: Holotype (CPC 21996), and paratypes A to 0 (CPC 21997 to 22000)

Type age (chronostrat): Early Miocene; planktonic zone N.8

Type locality: Sample F.434, Kindan section, locality 100, Wabag 1:250000 Sheet area, Papua New Guinea

Type repository: Canberra, Australia; Commonwealth Palaeontological Collection

Diagnosis: A species of Clavatorella with well-separated chambers, test surface finely reticulate, also finely hispid on some specimens. Aperture with narrow portieus, and relict aperture on penultimate chamber of some specimens.

Description: Test low, trochospiral, umbilicus wide, open, consisting of 10 to 12 chambers in two whorls, 4 or 5 chambers visible from ventral side. Chambers of first whorl tightly coiled, increasing only slowly in size, those of second whorl increasing rapidly in size and becoming radially elongate, more loosely coiled and distinctly separated. Dorsal and ventral sutures narrow, deeply depressed, radial. Wall of test perforate, surface finely reticulate. on some specimens also finely hispid. Aperture interiomarginal, umbilical-extraumbilical, arched, with imperforate umbilical extension (porticus) developed on last two chambers of some specimens: a relict aperture is present occasionally along umbilical margin of porticus of penultimate chamber.

Remarks: The new species prolata is placed in the sub-genus Clavatorella following the criterion given by Blow (1969), namely that this is a useful taxonomic category for turborotalid forms with clavate, radially elongate adult chambers. Small forms of G. (C.) prolata sp. novo show its turborotaliid relationships. The test is clearly trochospiral and there is no development of an apparent biumbilicate test, as noted by Blow (1969) for G. (C.) bermudezi.
G. (C.) prolata sp. novo does not have as highly arched an aperture as does the type-species of this subgenus, G. (C.) bermudezi (Bolli), particularly towards the equatorial periphery. Blow (1965) suggested that the aperture originally shown for G. (C.) bermudezi is a misdrawing. Edge views of bermudezi published by Blow (1965; 1969) show that the aperture is strongly arched near the equatorial periphery, and can give the impression of elongation of the aperture into the apertural face in the plane of coiling. The aperture of prolata sp. novo is uniformly arched, and is not strongly developed on small forms.
The chambers of G. (C.) prolata sp. novo are more clearly separated than are those of other described species of this subgenus.
Blow (1965) noted that Clavatorella is the Neogene analogue of the Cretaceous genus Clavihedbergella Banner & Blow, 1959, but differs in that it lacks a porticus or well-marked relict apertures. On some specimens of G. (C.) prolata sp. nov., a relict aperture can be seen on the penultimate chamber. G. (C.) oveyi Buckley, 1973 is the only other described species referred to Clavatorella which has distinct relict apertures and portici.

References:

Belford, D. J. (1984). Tertiary foraminifera and age of sediments, Ok Tedi-Wabag, Papua New Guinea. Australia Bureau of Mineral Resources Geology and Geophysics, Bulletin. 216: 1-52. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia (Clavatorella) prolata Belford 1984

Globorotalia (Clavatorella) prolata

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