pforams@mikrotax - Subbotina cancellata

Citation: Subbotina cancellata Blow 1979

Basionym: Subbotina triangularis cancellata Blow 1979

Synonyms:

? Globigerina fringa Subbotina, 1953:62, pl. 3: fig. 3 [Danian, Pecten horizon, Azov-Black Sea flysch, Anapa, Caucasus].
Subbotina triangularis cancellata Blow, 1979:1284, holotype: pl. 80: fig. 7 [Zone P2, DSDP Hole 20C/6/4: 72-74 cm], paratypes: pl. 80: figs. 2-6, 8, 9 [Zone P2, DSDP Hole 20C/6/4: 72-74 cm; Brazil Basin, South Atlantic Ocean], pl. 238: fig. 6 [enlargement of pl. 80: fig. 4]. [Olsson et al. 1999]

Taxonomic discussion: Blow (1979) recognized the significance of the coarsely cancellate wall as a primary taxonomic character. The coarsely cancellate wall is a diagnostic feature of the cancellata -velascoensis lineage. Blow's figures only showed umbilical views of his new taxon. Spiral views (Plate 24) show a rounded, somewhat lobulate outline, with the ultimate chamber varying in size from slightly smaller to distinctly larger than the penultimate chamber, and the coarse cancellate wall of the earlier chambers. The axial periphery is broadly rounded. [Olsson et al. 1999]

In his discussion of this species, Blow (1979) emphasized the apertural lip, which he identified as a porticus. He believed that the porticus was a feature that was added as a later ontogenetic structure to the test. He based his belief on his study of the structure, which in a SEM (1979, pi. 238: fig. 6) he interpreted as an infilling of pore-pits. At that time little was known about the ontogeny and gametogenesis of planktonic foraminifera. It is quite clear now that the lip forms as an extension of the primary chamber wall and that the cancellate texture develops throughout ontogeny and is enhanced during gametogenesis. The cancellate texture does not develop on the apertural lip, which, apparently, led Blow to interpret it as a separate, late-stage structure. [Olsson et al. 1999]

Blow named cancellata as a subspecies of Subbotina triangularis (White); however, triangularis has a distinctly different wall texture (Plate 2: Figures 15, 16, Plate 26) than cancellata. The recognition of a coarsely cancellate Subbotina lineage separates cancellata from triangularis and elevates it to species level. [Olsson et al. 1999]

Considerable confusion exists on the correct identification of Globigerina fringa Subbotina, 1950. The species is mostly identified in the lower Danian in Cretaceous/Paleogene boundary sections and is regarded as one of the earliest Danian species. The small size of the original figures of the holotype and its morphologic similarity to Eoglobigerina eobulloides Morozova, 1959, suggested that these species are synonymous (see Toumarkine and Luterbacher, 1985). SEMs taken by FR of the holotypes of the two species, however, shows this not to be the case (Plate 8: Figures 10-12, Plate 9: Figures 7-9). The distinguishing characteristic of G. fringa is a coarsely cancellate wall texture, which is similar to that in Subbotina cancellata Blow (1979). Furthermore, the coarsely cancellate wall texture observed in G. fringa is an advanced development in the evolution of wall texture in the Danian and is not present in Zone Pa stratigraphic levels. In fact, G. fringa was described from the "Pecten Horizon," which is apparently an upper Danian horizon in the Elburgan Formation in the northwest Caucasus. [Olsson et al. 1999]

Coarsely cancellate Subbotina cancellata morphotypes (Plate 25: Figures 1-15) occur in Zone Pic at DSDP Site 356 in the Southern Atlantic Ocean. They appear to be quite similar to the SEM of the holotype of Globigerina fringa Subbotina, 1953, shown on Plate 9: Figures 7-9. These morphotypes are smaller than typical S. cancellata and have 4-4½ chambers in the ultimate whorl. Although Subbotina described this species as having 4 chambers in the ultimate whorl, she chose a 4½-chambered specimen as the holotype. Most of the specimens in a suite of adults from DSDP Site 356 are 4-chambered (Plate 25). Small immature specimens often have 4½ chambers in the ultimate whorl, and these specimens have an umbilical to a slightly extraumbilical aperture (Plate 25: Figures 4, 10). In the adult specimens, the inner whorl is composed of 4½ chambers. This ontogenetic progression proceeds from an Eoglobigerina morphotype to a Subbotina morphotype and suggests that S. cancellata may have evolved from E. eobulloides; however, the strong cancellate wall texture is a distinctive characteristic of Subbotina. In general test morphology the cancellata morphotypes at DSDP Site 356 are similar to Subbotina trivialis Subbotina, 1953, suggesting that cancellata evolved from this species by enhancement of the cancellate wall. [Olsson et al. 1999]

The development of a coarsely cancellate wall begins a lineage that extends through S. cancellata to Subbotina velascoensis (Cushman, 1925). Although it is tempting to apply the name fringa to the DSDP Site 356 cancellata morphotypes, we recommend that this not be done pending further study on the morphologic characteristics of this taxon and on the stratigraphy and phylogeny of the coarsely cancellate Subbotinas in Zone PI. [Olsson et al. 1999]

Thus, it is clear that identification of fringa and its taxonomy should be considered carefully when using literature data in interpretative studies. For example, Brinkhuis and Zachariasse (1988) included fringa (together with edita) in the monophyletic genus Parvularugoglobigerina Hofker, 1978, emended, which is characterized by having a microperforate, nonspinose wall texture. Similarly, specimens identified by Keller (1988) as fringa (and indeed, other forms as cf. edita, hemisphaerica, and taurica) from the basal Paleocene of El Kef (Tunisia) are microperforate, nonspinose forms referable to Parvularugoglobigerina. [Olsson et al. 1999]

Distinguishing features:
Parent taxon (Subbotina): Low trochospiral, tripartite test, with 3-4 rapidly inflating, globular chambers in final whorl. Umbilicus nearly closed by tight coiling. Wall cancellate with spines at nodes of the ridges, +/- spine collars.
This taxon: Test tightly coiled, compact, rounded, and slightly lobulate; 3½-4 chambers in final whorl. Aperture umbilical with broad, somewhat irregular lip. Wall coarsely cancellate on all chambers.

Description

Biogeography and Palaeobiology

The full geographic extent of this species at this time is unknown. The species has been identified from North Atlantic (Site 549) and South Atlantic (Sites 20C, 356) DSDP drill sites. [Olsson et al. 1999]
Aze et al. 2011 summary: Unknown, but found in North and South Atlantic; based on Olsson et al. (1999)

No data available. [Olsson et al. 1999]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light _¹³C and relatively heavy _¹⁸O. Sources cited by Aze et al. 2011 (appendix S3): Coxall et al. (2000)

Subbotina cancellata is believed to have evolved from S. trivialis in the middle part of Zone PI, possible Plb. It is the first species of the coarsely cancellate Subbotina lineage. A reduction in the number of chambers in the ultimate whorl to 3_ and an increase in test size characterizes Zones P2 to P4 morphotypes. [Olsson et al. 1999]

Biostratigraphic distribution

Geological Range:
Notes: Zone Pic to Zone P4, currently known range. [Olsson et al. 1999]
Last occurrence (top): within P4 zone (57.10-60.73Ma, top in Thanetian stage). Data source: Olsson et al. 1999
First occurrence (base): within P1c subzone (62.60-63.90Ma, base in Danian stage). Data source: Olsson et al. 1999

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 29

References:

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

Olsson, R. K., Hemleben, C., Berggren, W. A. & Huber, B. T. (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Institution Press, Washington, DC. (85): 1-252. gs

Subbotina, N. N. (1953). Foraminiferes fossiles d'URSS Globigerinidae, Globorotaliidae, Hantkeninidae. Bureau de Recherches Geologiques et Minieres. 2239: 1-144. gs

test outline:	Lobate	chamber arrangement:	Trochospiral	edge view:	Equally biconvex	aperture:	Umbilical
sp chamber shape:	Globular	coiling axis:	Low	periphery:	N/A	aperture border:	Thick lip
umb chbr shape:	Globular	umbilicus:	Narrow	periph margin shape:	Broadly rounded	accessory apertures:	None
spiral sutures:	Moderately depressed	umb depth:	Shallow	wall texture:	Cancellate	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Moderately depressed	final-whorl chambers:	3.5-4	N.B. These characters are used for advanced search. N/A - not applicable

Subbotina cancellata

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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