Catalog - Sphaeroidinellopsis subdehiscens paenedehiscens

CATALOG OF ORIGINAL DESCRIPTIONS: Sphaeroidinellopsis subdehiscens paenedehiscens Blow 1969

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 -> S -> Sphaeroidinellopsis -> Sphaeroidinellopsis subdehiscens paenedehiscens
Other pages this level: S. hancocki, S. nepenthes constricta, S. ovalis, S. quadrangularis, S. sphaeroides, S. subdehiscens paenedehiscens

Sphaeroidinellopsis subdehiscens paenedehiscens

Citation: Sphaeroidinellopsis subdehiscens paenedehiscens Blow 1969
Rank: sub-species
Described on page(s) : 386-387
Type specimens: PM P 49785
Type sample (& lithostrat): Bowden Formation.
Type age (chronostrat): Pliocene, Zone N .19 (= Sphaeroidinella dehiscens dehiscens Globoquaclrina altispira altispira Partial-range zone). Ranges from middle to upper part of Zone N. 17 (Upper Miocene) to lowest part of Zone N.20 (Pliocene).
Type locality: Holotype (figs. 4, 9) and figured paratype (fig. 5) from approximately 100 meters southeast of the Drivers River (sample E R. 195), in the San San Clay member of the Bowden Formation overlain by rubbly limestone of the Manchioneal Formation, exposed in a cliff along the Coast Road which runs just south of the Drivers' River, northern coast of Jamaica, West Indies [fide Robinson, 1969, Geol. Soc. Jamaica, Jour. , vol. 10, pp. fig. 4 ] .
Type repository: London, UK; NHM

Current identification/main database link: Sphaeroidinellopsis paenedehiscens Blow, 1969

Original Description

Test large, consisting of an unknown number of chambers arranged in a low trohospire but with three chambers only present in the final whorl. Early chambers barely visible externally and the sutures between the penultimate whorl of chambers and the secceeding chamber completely obscured by clear imperforate shell material. Sutures between the chambers of the last whorl also largely obscured by the imperforate cortex but shallow troughs mark their approximate courses. The chambers are embracing and inflated, subglobular and, in the last whorl, increase rapidly as added. The embracing but inflated chambers are without distinct sutural furrows and this gives the test an ovate, smoothly rounded outline. The inner wall is densely perforate but the perforations do not open to the exterior except where the surface has been abraded or where the cortex has been dissolved. The primary aperture is an elongate, slit-like opening extending from the umbilicus to almost over the dorsal peripheral shoulder. The aperture follows the line of the intercameral suture between the last and first chamber of the final whorl and js bordered by a crenulate and frilled margin of clear shell material (i.e., the cortex). The abrasion and solution of the cortex is most noticeable on the dorsal side and over the last chamber. No supplementary dorsal aperture.

Maximum diameter of holotype 0.72 mm.


Extra details from original publication
Sphaeroidinellopsis subdehiscens paenedehiscens is distinguished from S. subdehiscens subdehiscens by possessing a relatively much longer primary aperture, a more tightly coiled test in which the chambers are more embracing and in lacking clearly defined, externally visible sutural commissures between any of the three final chambers. S. subdehiscens paenedehiscens is consistently much larger than subdehiscens (s.s.). S. subclehiscens puenedehiscens differs from Sphaeroidinella dehiscens dehiscens (including forma immatura) by not having a dorsal supplementary aperture notwithstanding the test size of the taxon may often exceed that of S. dehiscens dehiscens forma immatura.

Editors' Notes


Blow, W. H. (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In, Bronnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967. E J Brill, Leiden 380-381. gs


Sphaeroidinellopsis subdehiscens paenedehiscens compiled by the pforams@mikrotax project team viewed: 6-12-2022

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Comments (1)

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Extra details from original publication(herein): Sphaeroidinellopsis subdehiscens paenedehiscens not Sphaeroidinella which would explain why S. paenedehiscens is quoted herein without brackets. I do not have how to check this one. I hope you do.

Jeremy Young (Tonbridge, UK)

Thanks - well spotted and good t have got that one sorted out. Jeremy

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