CATALOG OF ORIGINAL DESCRIPTIONS: Globorotaloides eovariabilis Huber & Pearson, in Olsson et al. 2006

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.


Higher levels: pf_cat -> G -> Globorotaloides -> Globorotaloides eovariabilis
Other pages this level: G. atlanticus, G. carcoselleensis, G. eovariabilis, G. falconarae, G. indigena anavenezuelana, G. indigena redissimilis, G. parvulus anasuteri, G. parvulus lateraliaperturus, G. quadrocameratus, G. suteri, G. suteri relizensis, G. trema, G. variabilis,

Globorotaloides eovariabilis

Citation: Globorotaloides eovariabilis Huber & Pearson, in Olsson et al. 2006
Rank: Species
Type locality: The holotype and paratype are from the middle Eocene of ODP Hole 647A (Sample 647A-50R-5, 101 cm) in the Labrador Basin, which was assigned to calcareous nannofossil Zone NP16 by Firth (1989). [Olsson et al. 2006]
Type age: middle Eocene - calcareous nannofossil Zone NP16
Type sample and level: DSDP 647A-50R-5, 101 cm
Holotype Repository: Washington; USNM
Type & figured specimens: PLATE 5.4, FIGURES 1-17; Holotype (USNM 523429) and paratypes (USNM 523430a, 523430b)

Current identification/main database link: Globorotaloides eovariabilis Huber & Pearson, in Olsson et al. 2006


Original Description
Type of wall: Normal perforate, coarsely cancellate, sacculifer-type wall texture, often with corroded interpore ridges resulting in a remnant wall texture consisting of distinct ‘rosettes’ around the pores.

Test morphology: Test outline lobate, subcircular in axial view, axial periphery rounded to very slightly compressed, biconvex, oval to egg-shaped in edge view; 3-3½whorls of slightly inflated chambers arranged in a flattened to slightly elevated trochospire; 14-15 chambers in adult tests, 4½-6 in the final whorl increasing moderately in size; umbilicus shallow to moderately deep and narrow; umbilical sutures moderately depressed, radial; spiral initially indistinct, later weakly depressed, radial; aperture a low umbilical- extraumbilical arch extending one-third towards peripheral margin, surrounded by a broad lip that extends into the umbilical area.

Size: Holotype (USNM 523429) maximum diameter 0.18 mm, breadth 0.10 mm; paratype a (USNM 523430) maximum diameter 0.13 mm, breadth 0.80 mm; paratype b (USNM 523430) maximum diameter 0.15 m, breadth 0.93 mm.

Etymology: Named as “dawn” variabilis because of its superficial resemblance to the much younger species Globorotaloides variabilis Bolli

Extra details from original publication
Distinguishing features. Differs from Globorotaloides quadrocameratus n. sp. by having 41/2 to 6, rather than 4-41/2, final whorl chambers that are less inflated and increase more gradually in size; differs from Globorotaloides variabilis by its smaller size and less flat inner whorl.

Discussion. This form has been widely recognized at high latitude sites using various species names and open nomenclature. It is included in Globorotaloides because of its coarsely cancellate wall texture and low, sometimes flattened spiral coil. Specimens frequently exhibit corroded interpore ridges with a remnant surface texture consisting of a distinct rosette pattern (Pl. 5.4, Figs. 4, 13-15). A high latitude form from the lower Eocene of Site 690 (Maud Rise) that may be related to this species was designated by Stott and Kennett (1990, pl. 5, figs. 3-4) as “Tenuitella” reissi (Loeblich and Tappan). This morphotype has a similar coarsely reticulate wall texture but it is higher spired and the equatorial margin is more compressed.

Phylogenetic Relationships. Descended from Globorotaloides quadrocameratus n. sp. during the early Eocene. Intermediate morphologies can be found (e.g., Pl. 5.5, Figs. 13-15).

Stratigraphic Range
. Lower Eocene-lower Oligocene, Zone E7 to Zone O1 at low latitudes, and Zone AE4-AO1 at high latitudes.

Geographic Distribution. Found at deep-sea sites in southern and northern high latitudes but not at middle or low latitudes.

References:

Coxall, H. K. & Spezzaferri, S. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene Catapsydrax, Globorotaloides, and Protentelloides. In, Wade, B. S. , Olsson, R. K. , Pearson, P. N. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 46(Chap 4): 79-124. gs

Olsson, R. K., Pearson, P. N. & Huber, B. T. (2006c). Taxonomy, biostratigraphy, and phylogeny of Eocene Catapsydrax, Globorotaloides, Guembelitrioides, Paragloborotalia, Parasubbotina, and Pseudoglobigerinella n. gen. In, Pearson, P. N. , Olsson, R. K. , Hemleben, C. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 5): 67-110. gs


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Globorotaloides eovariabilis compiled by the pforams@mikrotax project team viewed: 9-4-2020

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