Subbotina tecta


Classification: pf_cenozoic -> Globigerinidae -> Subbotina -> Subbotina tecta
Sister taxa: S. projecta, S. tecta, S. jacksonensis, S. corpulenta, S. eocaena, S. gortanii, S. crociapertura, S. yeguaensis, S. senni, S. roesnaesensis, S. utilisindex, S. angiporoides, S. minima, S. linaperta, S. patagonica, S. cancellata, S. hornibrooki, S. velascoensis, S. triloculinoides, S. triangularis, S. trivialis, S. sp.,

Taxonomy

Citation: Subbotina tecta Pearson & Wade 2015
Rank: Species
Synonyms:
Taxonomic discussion:

“A specimen of S. tecta was illustrated by Olsson and others (2006, plate 6.18, fig. 12) as S. yeguaensis. In the past, other specimens may have been assigned to either D. galavisi or S. yeguaensis (possibly including the specimen illustrated as Globigerina yeguaensis by Postuma, 1971); however, S. tecta is a very distinctive morphotype which may be confined to the uppermost Eocene and lowermost Oligocene” (Pearson and Wade, 2015:15). In addition to the holotypes and paratypes illustrated from Tanzania (Pearson and Wade, 2015, figs. 12.1-12.3, 13.1-13.7), we have found comparable specimens from DSDP Site 242 (Indian Ocean), ODP Site 647 (North Atlantic Ocean), IODP Site U1334 (equatorial Pacific Ocean) and the US Gulf Coast. Referred to as Subbotina sp. 1 in Wade and Pearson (2008). [Wade et al. 2018]

Catalog entries: Subbotina tecta

Type images:

Distinguishing features: Like S. eocaena but with more spherical chambers, a large, prominent, apertural tooth.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description


Diagnostic characters:

Subbotina tecta is closely related to S. eocaena (Gümbel) from which it probably evolved in the uppermost Eocene. It is distinguished from S. eocaena ... by its more spherical chambers (although note that the neotype drawing of S. eocaena has very spherical chambers) and by possessing a large and prominent tooth, which is evidently a modification of the slightly pustulose lip of S. eocaena. When well developed, the tooth is positioned high over the umbilicus and forms a distinct platform above the primary aperture... . The two species are linked by intermediate forms ... and their distinction may be subjective; however, a distinct tooth rather than an irregular lip is critical for our diagnosis of S. tecta and ... the chambers are almost always more spherical. The distinctive apertural system and tooth in S. tecta may have been related to feeding, for example for securing prey in the umbilical region, and if this is correct it could indicate that S. tecta was a separate biospecies with a particular dietary specialization. It is distinguished from S. yeguaensis by having a lower trochospire and less embracing, more spherical chambers. It is distinguished from Subbotina sp. 1 [= S. projecta n. sp. in this study] by having a lower trochospiral and narrower umbilicus, and generally, a less slender, blunter tooth” (Pearson and Wade, 2015:14-15). It is highly homeomorphic with Globigerina pseudoeocaena Subbotina (now considered a junior synonym of Subbotina yeguaensis, see Olsson and others, 2006) described from the lower middle Eocene. However S. tecta is differentiated from G. pseudoeocaena by its very spherical chambers and projecting lip. It is distinguished from Dentoglobigerina galavisi (Bermúdez) by its more globular chambers, lobate periphery and protrusive tooth. [Wade et al. 2018]


Wall type: Symmetrically cancellate, ruber/sacculifer-type wall texture, spinose. [Wade et al. 2018]

Test morphology: 10-13 near spherical chambers arranged in three whorls in “a low trochospiral, oval and strongly lobate in outline; in spiral view 3½ to occasionally 4 globular, embracing chambers in final whorl, increasing rapidly in size, sutures straight and depressed, becoming moderately incised between later chambers; in umbilical view 3½ globular chambers, increasing rapidly in size, sutures depressed to incised, straight, umbilicus small, aperture umbilical to slightly extraumbilical in position, obscured by a distinctive trapezoidal to triangular, non-porous, often pustulose tooth, with relict teeth of earlier chambers sometimes visible, the adjacent chamber shoulders sometimes distinctly pustulose; in edge view chambers globular in shape, embracing, tooth convex and arching over the umbilicus. Coiling direction is approximately random” (Pearson and Wade, 2015:15). [Wade et al. 2018]

Size: Maximum diameter of holotype 0.61 mm. [Wade et al. 2018]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Tooth
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:Deepwall texture:Spinoseshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:3.5-4.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Global, but most common in low and mid-latitudes, so far known to occur in the western Indian Ocean, equatorial Pacific Ocean, Caribbean Sea, Gulf of Mexico and Labrador Sea. [Wade et al. 2018]

Isotope paleobiology: No data available. [Wade et al. 2018]

Phylogenetic relations: Subbotina tecta descended from S. eocaena in the uppermost Eocene and forms a phylogenetic link to S. projecta n. sp. [Wade et al. 2018]

Similar species: Distinguished from S. yeguaensis by having a lower trochospire and less embracing, more spherical chambers.

Most likely ancestor: Subbotina eocaena - at confidence level 3 (out of 5). Data source: Pearson & Wade 2015, p14.
Likely descendants: Subbotina projecta;

Biostratigraphic distribution

Geological Range:
Notes: Subbotina tecta has a restricted range, confined to upper Eocene Zone E16 to lower Oligocene Zone O1, pending further investigations. “Questionable specimens illustrated by Raju (1971) are from the G. mexicana zone of India, here equivalent to Zone E14, hence likely from a lower stratigraphic level than we have been able to confirm, and he records the highest occurrence in G. sastrii zone, equivalent to Zone O1. We did not find this species in any middle Eocene cores from Tanzania. Blow (1979) illustrated a specimen from the middle Eocene of Tanzania (Zone P11 = Zone E9) that is quite convincingly S. tecta, but we have studied the type locality in many outcrop and borehole samples and never found this morphology, so we suspect contamination with an upper Eocene sample” (Pearson and Wade, 2015:15). [Wade et al. 2018]
Last occurrence (top): within O1 zone (32.10-33.90Ma, top in Rupelian stage). Data source: Pearson & Wade 2015
First occurrence (base): within E15 zone (34.68-35.89Ma, base in Priabonian stage). Data source: Pearson & Wade 2015

Plot of occurrence data:

Primary source for this page: Wade et al. 2018 - Olig Atlas chap.10 p.324;

References:

Aze, T. et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. gs :: ::

Bermudez, P. J. (1961). Contribucion al estudio de las Globigerinidea de la region Caribe-Antillana (Paleoceno-Reciente). Editorial Sucre, Caracas. 1119-1393. 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 :: ::

Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (2006a). Taxonomy, biostratigraphy, and phylogeny of Eocene Globigerina, Globoturborotalita, Subbotina, and Turborotalita. 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 6): 111-168. gs :: ::

Pearson, P. N. & Wade, B. S. (2015). Systematic taxonomy of exceptionally well-preserved planktonic foraminifera from the Eocene/Oligocene boundary of Tanzania. Cushman Foundation for Foraminiferal Research, Special Publication. 45: 1-85. gs :: ::

Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs :: ::

Raju, D. S. N. (1971). Upper Eocene to Early Miocene planktonic foraminifera from the subsurface sediments in Cauvery Basin, India. Jahrbuch der Geologischen Bundesanstalt, Sonderband. 17: 7-68. gs :: ::

Wade, B. S. & Pearson, P. N. (2008). Planktonic foraminiferal turnover, diversity fluctuations and geochemical signals across the Eocene/Oligocene boundary in Tanzania. Marine Micropaleontology. 68: 244-255. gs :: ::

Wade, B. S., Olsson, R. K., Pearson, P. N., Edgar, K. M. & Premoli Silva, I. (2018a). Taxonomy, biostratigraphy, and phylogeny of Oligocene Subbotina. 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 10): 307-330. gs :: ::

Weinzierl, L. L. & Applin, E. R. (1929). The Claiborne Formation on the Coastal Domes. Journal of Paleontology. 3(4): 384-410. gs :: ::


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Subbotina tecta compiled by the pforams@mikrotax project team viewed: 7-7-2020

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