Catalog - Pulvinulina scitula Catalog - Pulvinulina scitula

CATALOG OF ORIGINAL DESCRIPTIONS: Pulvinulina scitula Brady 1882

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 -> Pulvinulina -> Pulvinulina scitula
Other pages this level: P. arca, P. arca contusa, P. crassata, P. crassata densa, P. gilberti, P. menardii fimbriata, P. menardii tumida, P. scitula, P. tricarinata, P. tumida flexuosa, P. velascoensis

Pulvinulina scitula

Citation: Pulvinulina scitula Brady 1882
taxonomic rank: species
Type specimens: 1959.6. 25.1. - Lectotype designated by Banner & Blow 1960
Type age (chronostrat): Recent
Type locality: samples collected by the "Knight Errant" expedition to the Faroe Channel in 1880
Type repository: London, UK; NHM

Linked specimens: London, UK; NHM (1959.6.25.1)

Current identification/main database link: Globorotalia scitula (Brady, 1882)

Original Description

Description of lectotype: The fairly small test con.ists of about 14 chambers arranged in nearly three whorls, which comprise a low trochospire with 5-6 chambers in a whorl. The chambers are slightly embracing and uniformly and slowly enlarging; they are little, if at all, inflated dorsally but are slightly inflated ventrally. The equatorial profile of the test is subcircular and possesses a periphery which becomes increasingly, although still weakly, lobulate in ontogeny. The axial profile shows that the test is compressed dorso-ventrally; the peripheral margin is acutely rounded but it is not carinate or secondarily thickened (i. e., no pseudocarina is present). The sutures are slightly depressed, not limbate or thickened, and the spiral suture is weakly lobulate. The dorsal intercameral sutures are strongly recurved and vorticiform; the distal ends of these sutures are smoothly tangential to the periphery. In the earlier ontogenetic stages the proximal ends of the intercameral dorsal sutures meet the spiral suture at a broadly acute angle, but later in ontogeny these sutures meet the spiral suture almost at right angles. The chambers of the last whorl show a decrease in the amount of embrace dorsally and simultaneously become even less inflated on that side of the test than they were earlier; this is associated with a step-like appearance which develops between successive chambers on the dorsal surface of the last whorl. The ventral sutures are nearly radial; initially they are smoothly curved, but later they become slightly sigmoidal. The umbilicus is small and it is almost closed by an umbilical lobe of the last chamber. The primary aperture is interiomarginal, umbilical-extraumbilical; it is a low arch extending from the umbilicus for about three quarters of the length of the terminal basal suture. The aperture possesses a uniformly very narrow and thin lip. The apertural face is slightly concave in its distal region but is smoothly convex near the umbilicus; it is not clearly delimited from the ventral surface of the last chamber. The wall of the test is thin and is uniformly and very finely perforate except for a weakly pustulose area on the ventral surface of the first chamber of the last whorl (facing the terminal aperture). The surface of the test is fairly smooth and shows little trace of any original hispidity; it possesses a characteristic glistening and a somewhat translucent appearance. [Banner & Blow 1960]

Maximum diameter of lectotype: 0.31 mm. [Banner & Blow 1960]

Extra details from original publication

Taxonomic remarks: Brady (1882) first described, but did not figure, this species from samples collected by the "Knight Errant"" expedition to the Faroe Channel in 1880. The samples taken during this expedition are deposited in the British Museum (Natural History) and two slides labelled ""Pulvinulina patagonica d'Orbigny sp. = P. scitula Brady"" and ""Knight Errant, S.7, 530 fathoms,"" the latter in Brady's handwriting, are present in the ""Knight Errant"" collection. From this syntypic series a lectotype, here designated, described and figured (pl. 5, figs. 5a-c), has been isolated and it is now registered as specimen no. 1959.6. 25.1. in the British Museum (Natural History) records.

In 1884, Brady redescribed this species from samples collected by the ""Challenger"" Expedition; in this subsequent work he doubted the novelty of his species and referred the specimens to Pulvinulina patagonica (d'Orbigny) ( = Rotalina patagonica d'Orbigny 1839). However, we do not believe that Rotalina patagonica d'Orbigny is even congeneric with Pulvinulina scitula Brady and consequently regard the latter as a separate and distinct species. [Banner & Blow 1960]

Remarks. The lectotype is distinctly larger than any of the remaining syntypes in the Brady collection although we believe it to be fully conspecific with them. Blow (1959, p. 220, pl. 16, figs. 127a-c) proposed the name Globorotalia scitula gigantea for populations characterised by individuals of distinctly greater dimensions and which were, in fact, almost double the size of co-existing typical specimens in the Lower Miocene. Brady (1884, p. 693) also commented on the much greater size of specimens of this species found in the South Pacific deeps compared to those in the Faroe Channel. The smaller specimens (similar to our lectotype) appear earlier in time in the highest Aquitanian whereas G. scitula gigantea occurs after the extinction of the index species Globorotalia fohsi barisanensis (i. e., within the Lower Burdigalian). As the origin of G. scitula appears to be from the yet smaller form G. scitula praescitula (see Blow, 1959) this lineage may also demonstrate the increase in size of its members during evolution. Although the relationships of G. scitula scitula and G. scitula gigantea are not yet clear, there may be a geographic and/or bathymetric relationship in the distributions of these two forms and the ecological factors involved may be affecting incipient speciation.

Akers (1955) described Globorotalia canariensis (d'Orbigny) var. minima from the ""Middle"" and ""Upper"" Miocene of Louisiana. Blow (1959) has shown that this form actually ranges from the Upper Aquitanian to Upper Burdigalian and that it is better considered as the separate species Globorotalia minima Akers. It appears to have arisen directly from G. scitula praescitula and is distinguishable from G. scitula scitula (Brady) by its greater number of chambers per whorl, less re-curved, more radial intercameral sutures, more strongly convex ventral side and umbilicus. [Banner & Blow 1960]

Pulvinulina scitula Brady 1882 is referable to the subgenus Turborotalia Cushman and Bermudez 1949



Banner, F. T. & Blow, W. H. (1960a). Some primary types of species belonging to the superfamily Globigerinaceae. Contributions from the Cushman Foundation for Foraminiferal Research. 11: 1-41. gs O

Brady, H. B. (1882). Report on the Foraminifera. In Tizard and Murray, Exploration of the Faroe Channel, during the summer of 1880, in H.M.S. "Knight Errant," with subsidiary reports:. Proceedings of the Royal Society of Edinburgh. XI: 708-717. gs


Pulvinulina scitula compiled by the pforams@mikrotax project team viewed: 20-4-2024

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