CATALOG OF ORIGINAL DESCRIPTIONS: Praehedbergella subsp. grigelisi perforare Banner et al. 1993

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 -> P -> Praehedbergella -> Praehedbergella grigelisi perforare
Other pages this level: P. grigelisae, P. grigelisi perforare, P. pseudosigali, P. ruka, P. ruka contritus, P. ruka papillata, P. ruka ruka, P. sigali compacta, P. sigali rasilis, P. tatianae,

Praehedbergella grigelisi perforare

Citation: Praehedbergella subsp. grigelisi perforare Banner et al. 1993
Rank: sub-species
Type locality: North Sea
Type age: Earliest Aptian
Type sample and level: North Sea Well 20/2-2, 8300 m
Type & figured specimens: PI. 1, figs. 1a-d; Holotype. P52758, from North Sea Well 20/2-2, 8300 m, Earliest Aptian;PI. 1,figs. la-d. Paratypes. From North Sea Well 16/28-6RE; P52759 (4275 m), P52762 (4204 m) (both Early Barremian), P52760 (4000 m), P52761 (4075 m) (both Late Aptian).

Linked specimens: London, UK; NHM (PM PF 52758)

Current identification/main database link:


Original Description
Diagnosis: Characterized by the presence of perforation cones, the low trochospire, the relatively few chambers (about 5) in the first whorl, rapid opening of the spire and apparently narrow slit-like aperture.

Description: Adult test about 0.20 mm at its maximum diameter and comprises at least two whorls of chambers coiled in a low trochospire. There are about 5 chambers in the penultimate whorl, reducing to 4 or 4½ chambers in the last whorl. The spiral side is almost flat or slightly convex and the intercameral sutures are moderately depressed; the intercam- eral angle of sutural depression at the periphery is about 135°. The chambers themselves are symmetrical and increase sig- nificantly in size with growth, those (excluding the final chamber) in the last whorl become slightly depressed, being about ⅔ as high as long when viewed from the spiral side. The final chamber may be only slightly longer than high. The umbilicus is shallow and measures about 0.35 mm in diameter. The aperture appears to be a narrow slit and perforation cones are visible at least on chambers of the last whorl.

Etymology: After perforare, to pierce through, referring to the presence of perforation cones.

Extra details from original publication
Remarks. The presence of perforation cones in this subspecies is of particular interest since these have not previously been recorded for any member of this genus. In the related genus Blefuscuiana, forms exist with identical gross morphologies which may be distinguished only by the presence or absence of perforation cones (e.g. B. aptica (Agalarova) sensu stricto, B. infracretacea (Glaessner) (metatypes redescribed in this paper) and its perforation-cone-bearing equivalents called 'cf. aptica' by Gorbachik, 1986, and by Banner & Desai, 1988). Since several such pairs are known for this genus (see below) we now regard the presence or absence of perforation cones as being only of subspecific value. Similarly , in Praehedbergella, we use perforation-cones to distinguish subspecies when the gross morphology of the taxa is otherwise identical. Although P. grigelisi perforare resembles in all but generic characters the juvenile form of B. aptica depressa, the two do not occur consistently together and we regard them here as taxonomically separate. P. grigelisi is nomen correctum for P. grigelisae Banner & Desai, 1988.

Distribution. Central North Sea: Well 16/28-6RE(4000 m, 4075m, 4204m and 4275 m); Well 20/2-2 (8300 m).

Stratigraphy. Early Barremian to Late 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 :: ::


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Praehedbergella grigelisi perforare compiled by the pforams@mikrotax project team viewed: 14-7-2020

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