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.
Linked specimens: NHM (London) 52078 NHM (London) 52077 NHM (London) 52081 NHM (London) 52075 NHM (London) 52076 NHM (London) 52079 NHM (London) 52080
Current identification/main database link: Hedbergella speetonensis (Banner and Desai, 1988)
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.
Extra details from original publication
Synonym: Hedbergella planispira (Tappan), Longoria, 1974, p. 64-65, pl. 23, figs. 5-7, 17-18.
Remarks. We are unable to identify this species with any which have been previously described. The specimens called Hedbergella planispira by Longoria ( 1974) from the late Aptian cabri zone of La Drome, S.E. France, and from northern Mexico are conspecific with ours, but they are not muricate or macroperforate and are not Hedbergella planispira (Tappan) (compare Plate 3, figures 8-9). The tendency towards planispirality shown by the later chambers of some specimens of Blefuscuiana speetonensis suggest that this species may be ancestral to multi-chambered species of Blowiella recorded from stratigraphically higher horizons of the Late Aptian (e.g. “Globigerinelloides blowi” of Longoria (1974, pl. 4, figs. 4,7 from the ferreolensis zone).
Banner, F.T. & Desai, D., (1988). A review and revision of the Jurassic-Early Cretaceous Globigerinina,with especial reference to the Aptian assemblages of Speeton (North Yorkshire, England). Journal of Micropalaeontology, 7: 143-185. Longoria, J.F., (1974). Stratigraphic, morphologic and taxonomic studies of Aptian planktonic foraminifera. Revista Española de Micropaleontología, Numero Extraordinario: 5-107.
Banner, F.T. & Desai, D., (1988). A review and revision of the Jurassic-Early Cretaceous Globigerinina,with especial reference to the Aptian assemblages of Speeton (North Yorkshire, England). Journal of Micropalaeontology, 7: 143-185.
Longoria, J.F., (1974). Stratigraphic, morphologic and taxonomic studies of Aptian planktonic foraminifera. Revista Española de Micropaleontología, Numero Extraordinario: 5-107.
Blefuscuiana speetonensis compiled by the pforams@mikrotax project team viewed: 18-3-2018
Go to Archive.is to create a permanent copy of this page - citation notes