Catalog - Hantkenina australis

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Hantkenina australis

Citation: Hantkenina australis Finlay 1939

Type repository: Washington; USNM

A fully satisfactory description of this species cannot yet be given, as no well preserved, unbroken examples have yet been found. Though it occurs at a number of localities, it is generally so rare and fragile that a composite description must be drawn up from a number of specimens. The genus is, however, of such interest and importance that the record is made in spite of this.
The species is best described by a comparison with H. alabamensis, the genotype, which it most nearly resembles. It has similarly compressed chambers but the sutural gutters are deeper and more marked. No examples have been seen with other than five chambers. The spine, as in alabamensis, is directly adjacent to the next suture (not as in mexicana and its allies quite distant from it); it is of about the same relative legth when unbroken (as long as or longer than the distance from its base to the umbilicus) but instead of being practically straight as in alabamensis, it usually has a decided backward curve. A notable difference is that the succeeding chamber begins at the base of the spine at the same level as the previous one and does not start some distance up the spine, as is usual in alabamensis. The aperture is similar to that figured by Cushman (1924, Proc. U. S. Nat. Mus., vol. 66, art. 30, p. 3) but is narrower and the basal wings are distinctly less spread, diverging at less than 90°, instead of considerably more.

Paratype measures 0.6 mm. in diameter (without spines) and 0.3 mm. in thickness. The type will be figured later.

The figured specimen was the best then available and is from Waitangi No. 2 well, 1560 feet. It has the surface badly preserved, has evidently suffered distortion, shows the chambers much too swollen and the spines broken, though the other details mentioned are the same. It measures 0·6 mm. in diameter (without spines) and 0·3 mm. in thickness.

The type (which will be figured later) has been chosen from the Hampden section, locality 5179B (1¼ miles North of Kakaho Creek, upper blue clays, about 5 feet below the top) - an Upper Bortonian horizon. Five damaged but uniform specimens were found showing some perfect spines and a highly polished surface, minutely but distinctly perforate.

This species appears to be limited to the Upper Bortonian. Besides the two localities mentioned, it occurs at 3310 (Pahi marl, -with Zeauvigerina), 5319 (Mangaotoro S.E. Survey District, 1 mile 31 chains at 180° from trig U).

The Eocene species recorded from Mexico by Nuttall ( 1930, p. 272) have little similarity to the New Zealand form, with the possible exception of H. longispina, but this has a more open umbilicus, a lobulate periphery and a spine, though of similar length, not quite adjacent to the following suture.

References:

Coxall, H. K. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of the Hantkeninidae (Clavigerinella, Hantkenina and Cribrohantkenina). 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 8): 213-256. gs O

Finlay, H. J. (1939d). New Zealand Foraminifera: The Occurrence of Rzehakina, Hantkenina, Rotaliatina, and Zeauvigerina. Transactions of the Royal Society of New Zealand. 68(4): 534-543. gs

Nuttall, W. L. F. (1930). Eocene Foraminifera from Mexico. Journal of Paleontology. 4: 271-293. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Hantkenina australis Finlay 1939

Hantkenina australis

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