Catalog - Hantkenina gohrbandti

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Hantkenina gohrbandti

Citation: Hantkenina gohrbandti Rögl & Egger 2011

Type age (chronostrat): Eocene, zone E8

Type locality: Holzhäsl near Mattsee, Austria (47.59N; 13.12E)

Type repository: Vienna; Museum of Natural history, Dept of Geology & Palaeontology

Description of holotype (pl. 1, flg. 1, pi. 3, flg. 1 ): Planisplrally coiled, laterally compressed, bi-umbllicate, 4½ chambers in the final whorl, rapidly increasing in size; first chamber small and broken, second chamber rounded, third chamber ovate, fourth and fifth chambers radially elongate wlth pointed chamber ends, final chamber with a thickened nub; aperture a high equatorial arch with broad lips.

Test morphology: Planispiraly coiled, inner whorl with a slight trochosplral tendency, laterally compressed, bl-umbilicate peripheral outline stellate; 4½-6 chambers In the final whorl (first and second chamber commonly crushed in our material); chambers rounded in early stage, later ovate to triangular, extend rapidly In radial direction; the final and commonly also penultimate chamber end In a sharp tip or thickened nub. The nub appears as a rounded, hollow and perforated structure (pl. 4, fig. 5). Some juvenile specimens show the first occurrences of real tubulospines (pl. 2, figs 4-6 9, pl. 3, figs 10- 11 ). Interestingly, after developing a tubulosplne in the inner whorl, the following chambers are pointed or with a thickened nub. In thin-section the hollow tubulospine can be observed (pl. 4. fig. 4). From the material of K.H. Gohrbandt primitive tubulospines were described already by Coxall et al. (2003, pl. 6, figs 9, 16). Later, the specimens were placed In the new species H. singanoae (Coxall and Pearson, 2006. pi. 8.1 3. figs 16-17).

Type of wall: Weakly cancellate and perforate. non-spinose, pustules may be present (pl. 1. fig. 6. pl. 3. figs 6-8). In some fnal chambers fine furrows towards the pointed end are present (pl. 1, fig. 7, pi. 3, fig. 3).

holotype: maximum diameter 684 microns; paratypes 407 to 860 microns.

Named In honour of Klaus H. Gohrbandt (Gulf Breeze. Florida, USA; former employee of Rohol-Aufsuchungs AG, Vienna) for his fundamental work on the Paleogene of the Helvetikum north of Salzburg.

Distinguishing features: The new spades Hantkenina gohrbandti is distinguished from Clavigerinella, especially C. caucaslca Subbotina by the development of pointed chamber ends with a nub in the youngest chambers, forming a prototubulospine In sense of Coxall and Pearson (2006). In contrast to H. singanoae Pearson & Coxall (in Coxall and Pearson, 2006) the straight and pointed chamber ends differ clearly from the cylindrlcal, commonly hood-like chamber ends in H. singanoae (comp. pl. 3, fig. 13 of the holotype of H. singanoae). Primitive forms of H. mexicana, originally described as H. nuttali Tourmarkine, have broad triangular chambers, where the chambers continue without break In the blunt tubulosplnes (pl. 3. figs 14-15). Intermittent forms between H. gohrbandti and H. mexicana (forma nuttalli) show blunt, somewhat irregular tubulosplnes (pl. 2, figs 7-a). The transition between both species is also visible in the small grooves along proto-tubulospines and real tubulosplnes (pl. 3, figs 3, 11-12) which may correspond to protoplasmatic structures.

Phylogenetlc relationship: In the evolution from Clavigerinella to Hantkenina the new species is a transitional form between C. caucasica and H. mexicana. In C. caucasica rounded chamber ends are present throughout the final whorl (comp. pl. 4, fig. 1 ). The new species H. gohrbandti shows initially rounded chambers in the juvenile stage, followed by ovate-elongate chambers, and finaly chambers with a pointed tip, ending commonly In a hollow nub (comp. pl. 4, fig. 5). In some instances a true tubulospine is already developed In juvenile chambers (comp. pl. 4, fig. 4 ). In H. mexicana true tubulosplnes are constantly developed in the later chambers of the final whorl.

Discussion: Coxall and Pearson (2006) discussed the position of their new species H. singanoae in comparison to Clavigerinella. The development of proto-tubulospines and terminal nubs is different in all species of Clavigerinella and forms a transition to later species of Hantkenina. As demonstrated by Rogl & Egger (2010) in the material from the Holzhäusl section a more clear transition to H. mexicana can be explained by the straight and pointed chamber ends In H. gohrbandti. In the case of H. gohrbandti proto-tubulospines and terminal nubs are developed, supporting its assignment to the genus Hantkenina. The species H. singanoae is also present in our samples, but in small numbers (pl. 1, fig. 9), and the characteristic hood is rudimentarily developed (pl. 3, fig. 9)

Stratigraphic range: Mlddle Eocene, planktonic foraminifera Zone E8 (Guembelitrioidos nuttalli lowest-occurrence Zone), Nannotetrina fulgens Zone NP15, Sullivania glgas Subzone NP15b. New calibrations of Zone E8 with the younger part of magneto-chron C21n and C20r yield an estimated age span of 46.4 to 44.4 Ma (Wade et al., 2011 ).

Geographic distribution: At present, this species is known only from a short interval in the Holzhäusl section, township Mattsee N of Salzburg, Austria, belonging to the Ultrahelvetic thrust unit of the Eastern Alps.

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

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. gs

Rögl, F. & Egger, H. (2011). A new planktonic foraminifera species (Hantkenina gohrbandti nov. spec.) from the middle Eocene of the northwestern Tethys (Mattsee, Austria). Austrian Journal of Earth Sciences. 104: 4-14. gs

Wade, B. S., Pearson, P. N., Berggren, W. A. & Pälike, H. (2011). Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale. Earth-Science Reviews. 104: 111-142. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Hantkenina gohrbandti Rögl & Egger 2011

Hantkenina gohrbandti

References:

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