Catalog - Sphaeroidinella dehiscens subdehiscens Catalog - Sphaeroidinella dehiscens subdehiscens

CATALOG OF ORIGINAL DESCRIPTIONS: Sphaeroidinella dehiscens subdehiscens Blow 1959

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 -> Sphaeroidinella -> Sphaeroidinella dehiscens subdehiscens
Other pages this level: S. cellata, S. dehiscens excavata, S. dehiscens reticulata, S. dehiscens subdehiscens, S. disjuncta, S. ionica, S. ionica evoluta, S. ionica ionica, S. missionis, S. multiloba, S. rutschi, S. senni, S. spinulosa, S. transiens

Sphaeroidinella dehiscens subdehiscens

Citation: Sphaeroidinella dehiscens subdehiscens Blow 1959
Taxonomic rank: sub-species
Type specimens: Holotype: Plate 12, figures 71a-c, deposited in U.S.N.M. collection No. 625705.
Type sample (& lithostrat): From sample, No. RM 19514, auger line near Pozon, eastern Falcon;
Type locality: near Pozon, eastern Falcon; Venezuela
Type repository: Washington, USNM ; paratypes in NHM London and NHM Basel

Linked specimens: USNM-625706 USNM-625705

Current identification/main database link: Sphaeroidinellopsis seminulina (Schwager 1866)


Original Description

Test low trochospiral with three, seldom with three and one half, chambers in the last whorl; chambers, in general, rather embracing, sutures not depressed but usually fairly distinct, especially the suture between the last and earlier chambers; equatorial periphery slightly lobate with the test appearing ovate in equatorial profile; axial periphery rounded; umbilicus small or closed; aperture interiomarginal, umbilical, an elongate slit or low arch, often with thickened and crenulate margins composed essentially of a thickening of the outer cortex; wall calcareous, thick, composed of an outer cortex and a thick inner part which is radial in structure; inner part coarsely perforate, outer part smooth and glassy in reflected light.

Size:
maximum diameter of holotype, 0.50 mm.

Extra details from original publication
Remarks: This subspecies is distinguished from Sphaeroidinella dehiscens dehiscens (Parker and Jones) by its less embracing chambers, more distinctive sutures, less deeply set aperture, absence of supplementary apertures, a slightly more lobate equatorial periphery and a generally smaller overall test size. It is interesting to observe that C. D. Redmond (in Stainforth, 1948b, p. 124) recorded this form from the Miocene of Colombia, but did not regard it as typical Sphaeroidinella dehiscens dehiscens.

Recently, the writer observed this subspecies in Sicily where, in the uppermost Miocene basal Pliocene, transitional forms to Sphaeroidinella dehiscens dehiscens occur. Transitional forms from Sphaeroidinella seminulina seminulina (Schwager) (Pl. 12, fig. 7?)) occur in the uppermost part of the Globorotalia fohsi robusta Zone both in Trinidad and eastern Falcon.

Occurrence: Ranges from the uppermost part of the Globorotaiia fohsi robusta Zone to the Globigerina bidloides Zone, Pozon formation.

References:

Blow, W. H. (1959). Age, correlation, and biostratigraphy of the upper Tocuyo (San Lorenzo) and Pozon Formations, eastern Falcon, Venezuela. Bulletins of American Paleontology. 39(178): 67-251. gs

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Sphaeroidinella dehiscens subdehiscens compiled by the pforams@mikrotax project team viewed: 11-5-2026

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