CATALOG OF ORIGINAL DESCRIPTIONS: Globigerinatheka subconglobata subsp. luterbacheri Bolli 1972

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> G -> Globigerinatheka -> Globigerinatheka subconglobata luterbacheri
Other pages this level: G. barri, G. curryi, G. euganea, G. kutchensis, G. lindiensis, G. subconglobata luterbacheri,

Globigerinatheka subconglobata luterbacheri

Citation: Globigerinatheka subconglobata subsp. luterbacheri Bolli 1972
Rank: sub-species
Type locality: Outcrop No. 2 of Eckert (1963, figs. 6 and 7 , p. 1016; Level 32, p. 1019), in a small gully approximately 200 m. NNE of the barns of Alp Unter-Looegg (1373 m), on the south slope of the Schimbrig, valley of the Grosse Entlen, Central Switzerland (Map: Landeskarte der Schweiz, 1:25000, Schiipfheim, Blatt 1169).
Type age: Globorotalia cerroazulensis cocoaensis/Globigerinatheka seminvoluta Zone
Type sample and level: Sample AA3858, Globigerina-marls of the Niederhorn-Pilatus nappe, Switzerland
Type & figured specimens: Holotype: Plate 7, fig. 1 3 ; paratypes: plate 7 , figs. 1-12, 14-17, from .

Linked specimens: USNM-244924

Current identification/main database link: Globigerinatheka luterbacheri Bolli 1972


Original Description
Test free, compact, subglobular to almost globular to slightly elongate. Early coil low trochospiral, single chambers poorly visible because of strong thickening of wall. Two or three chambers prior to ultimate one are distinctly larger, three forming a whorl. Final chambers may be up to half the size of the test volume, covering the umbilical region of the early coil, but may also be only slightly larger or smaller than penultimate chamber in which case it may become difficult to distinguish it from a bulla. Wall calcareous, thick, coarsely perforate. Aperture in small early stage single, interiomarginal-umbilical, low-arched, slitlike, fairly wide. In medium sized and larger specimens last chamber with 2-3, seldom 4, sutural apertures, which are low-arched in specimens with small ultimate chamber, medium to fairly high-arched and wide in specimens with larger sized end chambers. Apertures may be bordered by a distinct rim. Apertures in particular of larger specimens may be covered by bullae, each again with 2-3 sub- sidiary apertures. The size of the bullae may vary con- siderably, from very small, often covering only part of a large aperture, to a size so large that it may become difficult to decide whether it is a large bulla or a rudimentary sized end chamber.
Coiling: Predominantly dextral.

Size: Greatest diameter: Holotype (PI. 7 , fig. 131, 0.55 mm; figured paratypes, 0.4 to 0.6 mm.

Extra details from original publication
Remarks: With both subspecies having a maximum test size of about 0.6 mm, luterbacheri resembles at first sight G. subconglobota euganea; but differs from it in often having a more elongate test (plate 7 , figs. 3, 4, 7, 8, 1 3 ) . The sutures between the last chambers are often fairly deeply cut and somewhat angular (fig. 9 ) in contrast to the much less pronounced ones in euganea, giving the whole test surface a more rugged appearance compared to the smoother, more rounded aspect of euganea. In particular the surface of the coil appears coarser in luterbacheri and the bullae vary more in size. Bullae covering only part of an aperture, as is not uncommon in luterbacheri, were so far not seen in euganea. Stratigraphically, euganea occurs from the upper part of the Globorotalia lehneri Zone to the lower part of the Orbulinoides beckmanni Zone, luterbacheri ranges from probably within the Orbulinoides beckmanni Zone into the Globigerinatheka semiinvoluta Zone.

G. subconglobata luterbacheri differs from G. mexicana kugleri in its more robustly built wall, more globular and compact test shape and larger size, from G. mexicana mexicana/barri in the more robust wall and distinctly larger test size, and from G . semiinvoluta in its coarser surface, generally larger size, and less highly arched apertures on the last chamber, which are often almost circular in semiinvoluta. Bullate forms are frequent in luterbacheri, very scarce in serniinvoluta.

It appears that luterbacheri branched off from the subconglobata stock within Orbulinoides beckmanni time, but may possibly also have originated from G. index index. Eckert (1963) regards the specimens figured on his plate 7, figs. 1-4, as an evolutionary sequence (Entwicklungsreihe) from G . semiinvoluta to G. barri. He assigns the forms without bulla (figs. 1a-c), and those with one and two bullae (figs. 2a-3c), or with not all apertures of the last chamber covered by bullae, to semiinvoluta, and those with three bullae, covering all apertures of the last chamber, to barri. The specimens of Eckert compare well in morphology and large size with those illustrated here as G. subconglobala luterbacheri, which were selected from his own original sample AA3858. Further examination of this sample did not reveal any G . senziinvoluta. Ecker’s concept of an evolution from semiinvoluta to barri can also not be accepted for barri occurs earlier and has its peak development in the Middle Eocene Globorotalia lehneri and Orbulinoides beckmanni zones, while G. semiinvoluta is restricted to the lower part of the Late Eocene.

Stratigraphic range: ? Orbulinoides beckmanni Zone, Truncorotaloides rohri Zone to within Globigerinatheka semiinvoluta Zone.

References:

Bolli, H. M. (1972b). The genus Globigerinatheka Bronnimann. Journal of Foraminiferal Research. 2(3): 109-136. gs

Eckert, H. R. (1963). Die obereeozaen Globigerinen-Schiefer (Stadund Schimbergerschiefer) zwischen Pilatus und Schrattenfluh. Eclogae Geologicae Helvetiae. 56: 1001-1072. gs

Myatliuk, L. V. (1970). Foraminifera from the flysch deposits of the Eastern Carpathians (Cretaceous-Palaeogene). Vses. Neft. Nauchno-Issled. Geol-Razved. Inst (VNIGRI), Trudy. 282: 1-225. gs

Premoli Silva, I., Wade, B. S. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of Globigerinatheka and Orbulinoides. 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 7): 169-212. gs


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Globigerinatheka subconglobata luterbacheri compiled by the pforams@mikrotax project team viewed: 31-3-2020

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