Daughter taxa (time control age-window is: 0-800Ma) | ||||
 |  | _P44031_Neo.JPG) | Globoquadrina conglomerata Low trochospiral test, equatorial periphery slightly lobate; aperture interiomarginal umbilical low arch with umbilical teeth | |
 |  |  | Globoquadrina dehiscens Low trochospiral, spiral side almost flat, umbilical side strongly convex; subquadrate; 3½-4 chambers in final whorl; umbilicus large, deep; aperture low, umbilical, covered by umbilical tooth | |
| Globoquadrina sp. Specimens which cannot be assigned to established species | ||||
Wade et al. (2018) adopted a resticted definition of Globoquadrina and removed all species except G. dehiscens to Dentoglobigerina. This opinion was not accepted by Brummer & Kucera (2022) who noted that "the extant species [G. conglomerata], endemic to the tropical Indo- Pacific, is genetically distinct from all other non-spinose taxa (Morard et al., 2019), requiring classification in a distinct genus. Because Dentoglobigerina is spinose according to Wade et al. (2018), we cannot assign the extant and ostensibly non-spinose species to this genus. Therefore, we here provisionally retain Globoquadrina, awaiting revision of the fossil species leading to the modern taxon.
Extended discussion of Wade et al (2018):
Although safely restricted to a single species by us, this genus has not always been a caged beast, but rather has rampaged up and down the stratigraphical column and across unrelated groups, devouring a wide variety of forms. Finlay’s (1947) original concept was for species which combine “the open umbilicus, terminal face, and apertural flaps of Globotruncana, the angular ventrally pointed chambers of Globorotalia, and the general compact shape of Globigerina” and he included in his genus not only Globorotalia dehiscens Chapman, Parr and Collins, but also Globorotalia centralis Cushman and Bermúdez (an Eocene form now considered Turborotalia), and two important Miocene species that are now placed in Dentoglobigerina (Globigerina altispira Cushman and Jarvis and Globigerina venezuelana Hedberg). Bolli, Loeblich and Tappan (1957:31) used it for forms that have an umbilical aperture and “apertural flaps covering each aperture” but Blow (1969:338 and 339) complained that this definition could also lead to inclusion of a wide variety of other forms. Even so, he used the genus for both the dehiscens and the altispira groups while recognizing that “this is probably an error”. By subsequently introducing the genus Dentoglobigerina for globigeriniform species with umbilical teeth, Blow (1979) arguably compounded the problem, because it left unresolved the status of related forms that lack umbilical teeth (e.g. tapuriensis) or those in which umbilical teeth are not obligatory. Because of this dilemma, subsequent workers have varied greatly in their method of delimiting Globoquadrina and Dentoglobigerina, perhaps unsure of the phylogenetic link between the types of the two genera and how, where, and when the boundary between them should be drawn (e.g., Kennett and Srinivasan, 1983; Bolli and Saunders, 1985; Spezzaferri, 1994). Both genera have frequently been used in inverted commas, expressing this uncertainty. [Wade et al. 2018]
Our solution is to broaden the concept of Dentoglobigerina so that it does not require possession of an umbilical tooth (see discussion under that genus), and because we recognize the type species of that genus (galavisi) as the progenitor of the entire clade, we apply the genus to almost all its descendants; all that is except dehiscens, type species of the now monospecific genus Globoquadrina. Partly this is because treating the genera as synonyms would make Globoquadrina the senior name, upsetting the established usage of Dentoglobigerina; partly also it recognizes the distinctive quadrate nature of dehiscens, a highly specialized and morphologically derived branch of the Dentoglobigerina clade. Our solution is similar to that first proposed by Parker (1967) who complained that using Globoquadrina as a form-genus would result in widespread polyphyly and hence it was best restricted to dehiscens and just one closely related variant. If this relationship between Dentoglobigerina and Globoquadrina is correct, it implies that Globoquadrina belongs in the spinose Family Globigerinidae. Despite this, we have not so far found evidence of spines or spine holes in G. dehiscens and it may have secondarily lost its spines (see discussion above under Family Globigerinidae). [Wade et al. 2018]
Catalog entries: Globoquadrina
Distinguishing features:
Parent taxon (Globigerinidae): Wall spinose, usually with 3½-6 globular chambers in final whorl, trochospiral or planispiral
This taxon: Trochospiral with quadrate to subquadrate profile; aperture in interiomarginal / umbilical-extraumbilical, one or more tooth-like projections extending into the umbilicus.
Morphology:
Wall type:
Geographic distribution
Phylogenetic relations
Most likely ancestor: Dentoglobigerina - at confidence level 3 (out of 5). Data source: Wade et al. 2018.
Geological Range:
Notes: Subzone M1b to mid Zone M14 (see discussion under G. dehiscens). [Wade et al. 2018]
Last occurrence (top): Extant. Data source: Total of ranges of the species in this database
First occurrence (base): within M1b subzone (21.12-22.44Ma, base in Aquitanian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Primary source for this page: Wade et al. 2018 - Olig Atlas chap.11 p.377; Kennett & Srinivasan 1983, p.178
Blow, W. H. (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In, Bronnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967. E J Brill, Leiden 380-381. gs Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs Bolli, H. M. & Saunders, J. B. (1985). Oligocene to Holocene low latitude planktic foraminifera. In, Bolli, H. M., Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge, UK 155-262. gs Brummer, G-J. A. & Kucera, M. (2022). Taxonomic review of living planktonic foraminifera. Journal of Micropalaeontology. 41: 29-74. gs Finlay, H. J. (1947). New Zealand foraminifera: Key species in stratigraphy - no. 5. New Zealand Journal of Science and Technology. 28(5): 259-292. gs Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs Loeblich, A. R. & Tappan, H. (1957b). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 173-198. gs Parker, F. L. (1967). Late Tertiary biostratigraphy (planktonic foraminifera) of tropical Indo-Pacific deep-sea cores. Bulletins of American Paleontology. 52(235): 115203-. gs Spezzaferri, S. (1994). Planktonic foraminiferal biostratigraphy and taxonomy of the Oligocene and lower Miocene in the oceanic record. An overview. Palaeontographia Italica. 81: 1-187. gs Wade, B. S., Pearson, P. N., Olsson, R. K., Fraass, A. J., Leckie, R. M. & Hemleben, C. (2018c). Taxonomy, biostratigraphy, and phylogeny of Oligocene and Lower Miocene Dentoglobigerina and Globoquadrina. 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 11): 331-384. gs References:
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Globoquadrina compiled by the pforams@mikrotax project team viewed: 20-9-2024
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