Catalog - Sphaeroidinellopsis hancocki

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.

Sphaeroidinellopsis hancocki

Citation: Sphaeroidinellopsis hancocki Bandy 1975

Type specimens: pl. 1, figs. 3-7 : holotype (fig. 3), no. 5913; and paratypes, nos. 59 14 (fig. 4), 5915 (figs. 5, 6), and 5916 (fig. 7).

Type sample (& lithostrat): within the uppermost part of the Gilbert Reversed Magnetic series of the geomagnetic polarity reversal stratigraphy (ca. 3.5 m.y. B.P.).

Type age (chronostrat): Upper Miocene, upper Messinian probably equivalent to the Kapitean Stage of New Zealand

Type locality: A depth of 368-370 em. in piston core V 20-163 (in the collections of Lamont-Doherty Geological Observatory of Columbia University), recovered in waters 2706 meters deep, on the eastern scarp of Ninetyeast Ridge, at lat. 17°12' S., long. 88°41' E., eastern Indian Ocean.

Type repository: Los Angeles; Micropaleontology Laboratory, University of Southern California, Los Angeles, California;

Test large, final whorl consisting of from four to five, rarely six, large round chambers arranged in a low trochospire. Early chambers obscured by wall thickening on spiral side, only partially visible through large apertural opening. Spiral suture visible only in later part of last whorl. Sutures between chambers of final whorl slightly depressed, shallow troughs marking approximate positions. Chambers inflated, essentially spherical, those in final whorl being subequal in size, covered by a very thick cortex. The final chamber may be radially elongate in kummerforms. Inner wall densely perforate (punctate), but perforations not opening to exterior surface unless cortex has been dissolved or not formed. Primary aperture a large rounded opening, laterally directed, which opens into a large open umbilicus, umbilical opening bordered by a crenulate and frilled margin. No supplementary dorsal apertures; cortex may be damaged or incomplete dorsally, showing apparent openings on the spiral side that do not extend into interior unless the primary shell has been dissolved or destroyed.

Dimensions. - Holotype (fig. 3), maximum diameter 0.93 mm., thickness 0.67 mm.: paratype (fig. 4), maximum diameter 0.83 mm., thickness 0.58 mm.; paratype (figs. 5, 6), maximum diameter 0.84 mm., thickness 0.59 mm.; paratype, maximum diameter 0.79 mm., thickness 0.56 mm.

Remarks. - Sphaeroidinellopsis hancocki, new species, is distinguished from S. seminulina (Schwager) [Globigerina seminulina, 1866], as neotypified by Banner and Blow (1960, Cushman Found. Foram. Res., Contr., vol. 11 , pt. 1, p. 24), primarily in having a very thick test with large inflated or globose chambers. Sphaeroidinellopsis seminulina has a more flattened test; the maximum diameter of the test (neotype) of 0.56 mm. is about the same as the thickness of the test in this new species. Sphaeroidinellopsis seminulina kochi (Caudri) [Globigerina kochi, 1934] differs from this new species in having a thinner or much more compressed test in edge view, with its later chambers radially elongate, and it also tends to develop an apertural lip in the last chamber, whereas this new species retains a flange. Sphaeroidinellopsis sphaeroides Lamb has three chambers in the final whorl, with a broadly oval test outline, sutures obscure; it is smaller (holotype measures about 0.56 mm. in maximum length), and the aperture is a flanged slitlike opening with no umbilicus. The types of Sphaeroidinellopsis rutschi (Cushman and Renz) [Sphaeroidinella rutschi, 1941] and S. grimsdalei (Keijzer) [Globigerina grirnsdalei, 1945] show them to be more cJosely related to the S. seminulina group. They appear to develop a lip in the last chamber, they are more compressed, and their chambers are more radially elongate rather than equidimensional."

References:

Bandy, O. L. (1975). Messinian evaporite deposition and the Miocene/Pliocene boundary, Pasquasia-Capodarso Sections, Sicily. In, Saito, T. & Burckle, L. H. (eds) Late Neogene Epoch Boundaries. American Museum Natural History Micropaleontology Press, New York 49-63. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Sphaeroidinellopsis hancocki Bandy 1975

Sphaeroidinellopsis hancocki

References:

Add Comment

Comments