Catalog - Globigerina quinqueloba egelida

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.

Globigerina quinqueloba egelida

Citation: Globigerina quinqueloba egelida Cifelli & Smith 1970

Type specimens: PLATE 3: FIGURES 4, 5, 6, 7

Type age (chronostrat): Recent - plankton

Test trochospirally low with a rounded, lobate periphery, and with up to three and occasionally part of four whorls; chambers subspherical. enlarging fairly rapidly and at an even rate, usually with four and a half to five in the peripheral whorl which are visible on both sides of the test, and averaging a total of 13 or 14 in the adult test, forming a low. conical spire on most specimens but almost planar in others, final chamber often itself extended or with a thin lip or flap extending downward to partially cover the aperture, occasionally a reduced final chamber or a bulla covering the aperture; aperture interiomarginal, umbilical to umbilical-extra umbilical subrounded; sutures distinct, narrow, depressed, radial on both sides: wall finely perforate, thin, finely hispid or spinose but with occasional speccimins having a few coarser spines around the peripheral parts of the chambers, sometimes in combination with a reduced final chamber: direction of coiling about equally divided between left and right.

Globigerina cf. quinqueloba Natland. Todd and Bronnimann, 1957, p. 40, pi. 12: figs. 2, 3. Bé, 1959, pl. 1: figs. 21, 22.
Globigerina aff. G. quinqueloba Natland. Cifelli, 1965, p. 13, pl. 2: figs. 3,4.

According to F. L. Parker (personal communication) paratypes of Globigerina quinqueloba Natland presumably deposited at the Scripps Institution of Oceanography are not there, so that the holotype, deposited at the National Museum of Natural History is the only available primary type. The holotype of Globigerina quinqueloba Natland resembles G. quinqueloba egelida, but does not fall within the range of variation of the North Atlantic assemblages included within this new subspecies. The chief differences are that the test of the holotype is thicker walled, more compact, with less depressed sutures and a less lobulate periphery. Of these differences, the only one possibly a result of the holotype being a bottom-sediment specimen is the thicker wall. Moreover, the holotype is thicker with respect to its maximum diameter than G. quinqueloba egelida and also appreciably larger in maximum diameter. In G. quinqueloba egelida, the aperture is small and either open and semicircular, often with a thin lip, or modified and partially covered by the final chamber which may form a flap that obscures, but does not completely close over the aperture (bullae are seldom seen). State of preservation of the holotype prevents determination of whether there may be a thin lip at the base of the flap. In contrast to G. quinqueloba egelida, however, the flap of the holotype is a gross feature that extends across the aperture, attaching to the chamber below, almost completely closing over the apertural area. Most adult specimens of G. quinqueloba egelida have a total of 13 chambers with between four and half and five in the peripheral whorl, which is the same as the holotype of G. quinqueloba.

Comparison between Globigerina quinqueloba egelida, new subspecies, and G. quinqueloba, sensu stricto, has been made from a suite of specimens from the approximate type-locality, kindly furnished us by F. L. Parker. This suite of specimens appears to show a gradation between the holotype of G. quinqueloba and G. quinqueloba egelida. As a group, the specimens are closer to the holotype in the thicker, more coarsely hispid and perforate wall, compactness and thickness of test, relatively slight depression of sutures and the pronounced apertural coverings and flaps. The majority of specimens, however, are not as thick or as compact as the holotype, and the holotype, therefore, appears an end member of the populations of the species that we have seen.

All assemblages of Globigerina quinqueloba that we have observed in North Atlantic plankton tows are referable to G. quinqueloba egelida, new subspecies. Thus we include in our synonymy those figured as G. cf. quinqueloba by Bé (1969) and G. aff. G. quinqueloba by Cifelli (1965). The assemblages from bottom sediments in the Gulf of Paria figured by Todd and Bronniman (1957) as G. cf. quinqueloba are referable to the new subspecies, as are the specimens from North Atlantic bottom sediments figured as G. quinqueloba by Phleger, Parker, and Pierson (1953).

The specimen figured by Bradshaw (1959) as G. quinqueloba from Pacific plankton appears to belong to G. quinqueloba, sensu stricto. A close similarity exists between G. quinqueloba egelida, new subspecies, and the subarctic planktonic form with five chambers in the peripheral whorl referred by many to G. pachyderma. Characteristically, however, that form is larger and thicker than the present specimens, has a more umbilical and more open aperture, and a heavier wall. The relationship between these two forms needs further investigation.

A form with a few coarser spines and reduced, rather peculiarly shaped final chambers might represent a distinct group, but specimens of this sort are only occasionally seen and the relationship is difficult to determine. Comparison between G. quinqueloba egelida, new subspecies, and G. atlantisae, new species is made under G. atlantisae (p. 17).

MEASUREMENTS. The relationship between chamber number and test volution in ten specimens of Globigerina quinqueloba egelida is shown in Figure 20. Chamber addition in this species is relatively consistent through ontogeny, probably most closely comparable with G. atlantisae, new species (Figure 11). Spread of points is relatively low through whorls, and the decrease in chamber number with respect to test volution in the peripheral whorl is negligible. The minimum number of chambers recorded was 11 and the maximum 16, contained in 1110°, or slightly more than three full whorls. In the majority of specimens there were 13 to 14 chambers, contained in 800° to 1000°; or between two and three whorls; all specimens completed more than two whorls. The number of chambers in the peripheral whorl was four to five. In the preperipheral whorl the chamber number is about the same. The number of chambers in the peripheral whorl of G. quinqueloba egelida tends to be slightly greater than in G. atlantisae and even slightly more so than in G. incompta (Figures 11, 20).

DISTRIBUTION. Globigerina quinqueloba egelida, new subspecies, occurs in most of the samples examined. They account for less than 10 of the assemblage in eleven Atlantis 77-13 and six Atlantis 11-9 samples, 15 and 20 percent in two Atlantis II-9 samples, and 21, 22, 53, and 55 percent in five Atlantis 11-13 samples (stations 29, 4, 28, 16, and 26, respectively).

Brummer & Kucera 2022 re-examined the holotype and concluded that it was a growth stage of T. quinqueloba

References:

Cifelli, R. J. & Smith, R. K. (1970). Distribution of planktonic foraminifera in the vicinity of the North Atlantic Current. Smithsonian Contributions to Paleobiology. 4: -. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina quinqueloba egelida Cifelli & Smith 1970

Globigerina quinqueloba egelida

References:

Comments (0)

Add Comment