Catalog - Sphaeroidinellopsis sphaeroides

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Sphaeroidinellopsis sphaeroides

Citation: Sphaeroidinellopsis sphaeroides Lamb 1969

Type specimens: pl. 1, figs. 1-5 ; pl. 2, figs. 1-3: holotype 688319 (pl. 1, fig. l ; pl. 2, figs. 1-3),; paratypes, nos. 688320-688323 (figs. 2, 3, 5, 4, respectively).

Type sample (& lithostrat): 207-209 cm. in core 64-A-9-SE,

Type age (chronostrat): Upper Pliocene. Ranges down to upper Miocene

Type locality: Texas A & M Sigsbee Knolls core 64-A-9-SE, taken at a depth of 3536 m. at lat. 23° 50' N. , long. 92°24.5'W., Sigsbee Knolls, Gulf of Mexico.

Type repository: Washington, USNM

Test a low trochospire, globigerine in form, usually with three chambers in final whorl. Primary surface of chambers reticulate and pitted with deep pores; later covered by a thick, smooth secondary layer or layers of calcareous material (cortex) which constricts the pores and gives a shiny, finely perforate appearance. Test outline broadly oval to nearly spherical with chambers and sutures obscured by cortex and not clearly visible. Aperture single, intraumbilical with flange-like lips surrounding the a pertural opening; lips developed as extension of the cortex, projecting forward slightly. giving a puckered appearance. Aberrant chambers developed commonly, composed of cortex and usually with no visible internal globigerine chamber.

Diameter up to about 0.7 mm., usually smaller.

Sphaeroidinella seminulina (Schwager). - Parker, 1967, Bull. Amer. Pal., vol. 52. no. 235, pp. 161, 162, pl. 23, figs. 1-4.
Sphaeroidinellopsis seminulina (Schwager). - Poag and Akers, 1967, Cushman Found. Foram. Res., Contr., vol. 18, pt. 4, p. 172, pl. 17, figs. 18-20. - Bermudez, 1961, Congr. Geol. Venezolano, 3rd, Mem., Dir. Geol., Bol. Geol., Publ. Espec., no. 3 (1960), p. 1279, pl. 9, fig. 7. - Ingle, 1967, BulI. Amer. Pal., 1967, vol. 52, no. 236, p. 357, pl. 43, fig. 7.
Sphaeroidinella subdehiscens Blow. - Parker, 1967, op. cit., p. 162, pl. 23, figs. 6, 7.
Sphaeroidinella dehiscens (Parker and Jones). - Parker, 1967 (part), op. cit., p. 160. pl. 23, fig. 8.

Remarks. This species differs from Sphaeroidinellopsis seminulina (Schwager) and Sphaeroidinellopsis subdehiscens (Blow) in having a more spherical test outline and flange-like. protruding lips enclosing the aperture. The species develops from either S. seminulina or S. subdehiscens in Late Miocene by growth of flange-like apertural lips about the aperture, which in the former species are restricted to the early chambers. Individual specimens may show a break in the cortex, or solution pits, along the sutures on the spiral side, but these should not be mistaken for true secondary apertures as seen in Sphaeroidinella dehiscens (Parker and Jones). Forms with one or more aberrant chambers may resemble Sphaeroidinellopsis kochi Caudri.

References:

Lamb, J. L. (1969). Planktonic foraminiferal datums and late Neogene epoch boundaries in the Mediterranean, Caribbean, and Gulf of Mexico. Transactions of the Gulf-Coast Association of Geological Societies. 19: 559-578. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Sphaeroidinellopsis sphaeroides Lamb 1969

Sphaeroidinellopsis sphaeroides

References:

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