Hedbergella speetonensis

Taxonomy

Original description: The test is a low trochospire with about six chambers in the first whorl and five to seven chambers in the final whorl. The spiral side is typically wholly evolute and flat (PI. 7, figs. 1-2) but may become slightly involute and concave (PI. 7, figs. 3-4) with growth or with reduction of chamber number or both. The intercameral sutures of the spiral side are straight and slightly oblique and become increasingly depressed in the final whorl as the chambers become increasingly globular. The umbilicus is moderately broad (with breadth about 25% of the test diameter) and open; the intercameral sutures on the umbilical side are virtually radial. On both the spiral and umbilical sides, the initially reniform chambers are broadest toward their posterior ends, this asymmetry giving the earlier chambers a slightly "swept back" appearance, like ovoids with the narrower end to the anterior; the later chambers of the last whorl become subglobular. The aperture is a low arch, in early chambers extending from the umbilicus to the periphery of the previous whorl, but in the later chambers it may extend over the periphery to encroach slightly onto the spiral side. The aperture has a porticus throughout its length, broadest posteriorly. Relict apertures and portici are visible in the umbilicus for about half of the last whorl. The surface of the test is smooth, not muricate, and is microperforate, with external diameters about 0.006 mm. The whole surface is microperforate except for the umbilical shoulders, which may be imperforate.

Entries in the Catalog of original descriptions: Blefuscuiana speetonensis

Geological Range:
Last occurrence (top): within G. algerianus zone (116.86-118.24Ma, top in Aptian stage). Data source: [copied from Chronos database]
First occurrence (base): within H. similis zone (124.40-126.01Ma, base in Barremian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

• Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
• Triangles indicate an event for which a precise placement has been suggested
• (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Hedbergella

Hedbergella speetonensis compiled by the pforams@mikrotax project team viewed: 26-4-2025 Taxon Search: Advanced Search Short stable page link: https://mikrotax.org/pforams/index.php?id=110266 Go to Archive.is to create a permanent copy of this page - citation notes

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