Catalog - Praehedbergella ruka papillata

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Praehedbergella ruka papillata

Citation: Praehedbergella subsp. ruka papillata Banner et al. 1993

Type specimens: PI. 1, figs. 5a-c Holotype. PS2736

Type age (chronostrat): Early Aptian.

Type locality: Central North Sea (Well 16/28-6RE), 415O m,

Characterized by its high trochospire, strong dorsal convexity, depressed chambers (excluding the last) in the final whorl, a papillate test surface, covered with abun- dant perforation cones, and a thick porticus. The final chamber may be subglobular.

After papillatus, with buds (referring to the presence of abundant perforation cones).

REMARKS. This subspecies appears not to have been recognised by any previous workers. Although it is distinguished by the presence of its perforation cones, it can be morphologicaUy otherwise identical to the typical form of the species (see PI. 1, compare figs. Se and 3c). P. ruka papillata appears to be analogous to Guembelitria cretacea Cushman, which also has perforation cones formed over its microperforations, while P. ruka ruka would be analogous to Gallitellia vivans (Cushman), which has a smooth microperforate surface (see Loeblich and Tappan, 1988, PI. 485, figs. 13, 1112); such distinctions were used by Loeblich and T appan (1988 , p. 453) to distinguish between the genera Guembelitria and Gallitellia. However, we use this criterion to distinguish only subspecies (not even species, much less genera) because we, as yet, do not know of any stratigraphic difference between the geological ranges of these taxa (in contrast, Guembelitria ranges Cretaceous-Palaeogene, while Gallitellia is Quaternary). However, the geographical distribution of the subspecies may prove to be different.
The thick, broad, heavy porticus, which appears to characterise P. ruka papillata (PI. 1, fig. 5a) is apparently not typical for other taxa which bear perforation cones, either in the Globigerinacea (e.g. P. grigelisi perforare, PI. 1, fig. la, and Blefuscuiana infracretacea (Glaessner), PI. 4, fig. 2, PI. 8, fig. 1) or the Heterohelicacea (e.g. Cassigerinella boudecensis Pokorny, see Li Qianyu, 1986).
DISTRIBUTION. Central North Sea.
STRATIGRAPHY. Early Aptian.

References:

Banner, F. T., Copestake, P. & White, M. R. (1993). Barremian-Aptian Praehedbergellidae of the North Sea area: a reconnaisance. Bulletin of the Natural History Museum, London (Geology). 49: 1-30. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Praehedbergella subsp. ruka papillata Banner et al. 1993

Praehedbergella ruka papillata

References:

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