Hantkenina singanoae


Classification: pf_cenozoic -> smooth non-spinose -> Hantkeninidae -> Hantkenina -> Hantkenina singanoae
Sister taxa: H. alabamensis, H. australis, H. compressa, H. dumblei, H. lehneri, H. liebusi, H. mexicana, H. nanggulanensis, H. primitiva, H. singanoae, H. sp.,

Taxonomy

Citation: Hantkenina singanoae Pearson & Coxall, in Coxall & Pearson 2006
Rank: Species
Basionym: Hantkenina singanoae
Synonyms:
  • Clavigerinella-Hantkenina transition” Coxall and others, 2003:250, pl. 6: figs. 3, 16 [lower middle Eocene, Helvetikum Section, Buntmergelserie, Austria, Gohrbandt (1967) sample 64/1-36/4b].
  • transitional Hantkenina sp. Pearson and others, 2004:37, pl.2: figs. 18-21 [Zone E7, TDP Site 2, Tanzania].
Taxonomic discussion: The species is erected to include a range of diverse morphologies that appear transitional between Clavigerinella caucasica and H. mexicana. The Clavigerinella caucasica -Hantkenina singanoae interface is not clear-cut because the transition between the two is gradual. However, we favor placing singanoae in Hantkenina rather than Clavigerinella because it possesses proto-tubulospines and/or terminal nubs, structures that are considered homologous to tubulospines. No such structures are present in Clavigerinella. [Coxall & Pearson 2006]
Etymology: Named in honor of Dr. Joyce M. Singano, chief micropaleontologist at the Tanzania Petroleum Development Corporation. [Coxall & Pearson 2006]

Catalog entries: Hantkenina singanoae;

Type images:

Short diagnosis: Hantkenina singanoae differs from Clavigerinella caucasica by possessing rudimentary terminal constrictions and/or cylindrical extensions to the chamber ends. It differs from H. mexicana in lacking true non-porous tubulospines.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: Hantkenina singanoae differs from Clavigerinella caucasica by possessing rudimentary terminal constrictions and/or cylindrical extensions to the chamber ends. It differs from H. mexicana in lacking true non-porous tubulospines. [Coxall & Pearson 2006]

Wall type: The wall is layered and perforate, with a smooth or weakly cancellate surface

Test morphology: Planispiral or pseudo- planispiral, laterally compressed, 4-5 rapidly expanding chambers in the final whorl; final chamber, and up to three of the preceding chambers, radially elongate, at least one of these ending in either a terminal nub or cylindrical projection (‘proto-tubulospine’); proto-tubulospines are smooth and distinctly porous (although pore density may be reduced at the distal ends) in contrast to the true tubulospines of H. mexicana and subsequent species, which are usually imperforate; distal chamber ends can be inclined in an anterior, posterior or dorso-ventral direction and pseudo-tubulospines are commonly bent; aperture is a high equatorial arch with a smooth, broad lip; lips of relict apertures are commonly observed along the sutures of the final whorl; sutures are shallow and usually curved in a posterior direction.

Size: Maximum diameter of holotype (excluding proto-tubulospines) 0.63 mm.

Biogeography and Palaeobiology


Geographic distribution: So far only found in Tanzania and Austria. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Found only in Tanzania and Austria so far; based on Coxall & Pearson (2006)

Isotope paleobiology: No data available. [Coxall & Pearson 2006]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study

Phylogenetic relations: Hantkenina singanoae evolved from C. caucasica by constriction of the terminal chamber ends. This transitional form evolved into Hantkenina mexicana by further elongation of the protuberance and reduction in pore density to form elongated, nonporous tubulospines of Hantkenina proper. [Coxall & Pearson 2006]

Biostratigraphic distribution

Geological Range:
Notes: Restricted to uppermost lower Eocene Zone E7 and basal E8, overlapping slightly with Hantkenina mexicana. [Coxall & Pearson 2006]
Last occurrence (top): near base of E9 zone (10% up, 43.8Ma, in Lutetian stage). Data source: Wade et al. (2011), fig. 6
First occurrence (base): near top of E8 zone (90% up, 44Ma, in Lutetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 8, p. 252

References:

Coxall, H.K. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of the Hantkeninidae (Clavigerinella, Hantkenina and Cribrohantkenina). In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Allen Press, Lawrence, Kansas, pp. 213-256.

Coxall, H.K.; Huber, B.T. & Pearson, P.N., (2003). Origin and morphology of the Eocene planktonic foraminifera Hantkenina. Journal of Foraminiferal Research, 33: 237-261.

Pearson, P.N. & others, (2004). Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1–5. Journal of African Earth Sciences, 39: 25-62.


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Hantkenina singanoae compiled by the pforams@mikrotax project team viewed: 21-8-2017

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