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DIAGNOSIS. A Globotruncana with a large, circular, strongly spiroconvex, umbilico-convex or flat, test, "falsostuarti-like" keels, subpetaloid chambers and a wide tegillar area.
DESCRIPTION. Test large, spiroconvex, coiled in a high trochospire. Spiral side strongly convex, umbili- cal side slightly convex or flat. Equatorial periphery circular, slightly lobate with "falsostuarti-like" keels ; a distinct single keel or a well-developed and beaded primary keel and a weak umbilical secondary keel or traces of an umbilical keel. This umbilical secondary keel appears either as a weak keel on the earlier chambers of the final whorl or as traces of a secondary keel formed by the umbilical sutures and occurring at its point of exit on the periphery. There are 24 chambers on the spiral side, arranged in 31-4 dextrally coiled whorls and increasing regularly in size. The initial chambers are small, subglobular and are followed by subpetaloid chambers. The final whorl is composed of 6-8 larger, subpetaloid chambers which increase regularly in size in the direction of coiling. On the umbilical side they are subpetaloid to ovoid, and elongated in the direction of coiling. The umbilicus is wide and deep, and is surrounded by the periumbilical ridges, and covered by the tegilla. Primary aperture interiomarginal, umbilical. Accessory apertures intralaminal. The surface is nearly smooth and perforated, except for the tegilla and the keels. The wall is calcareous and perforate.
Etymology: Pseudos, greek, not real, and conica ;pseudoconica : not real conica.
Extra details from original publication
From its ancestor Globotruncana falsostuarti, Globotruncana pseudoconica nov. sp. differs in being larger, and possessing a more convex spiral side, a less convex umbilical side, less lobate periphery, subpetaloid chambers on both sides of the test. On the umbilical side the chambers are distinctly elongated in the direction of coiling.
As mentioned above, G. pseudoconica nov. sp. has evolved from G. falsostuarti SIGAL, and like its ancestor it appears in single and double keeled forms. This indicates that both varieties are descended from G. falsostuarti. The evolution took place probably in the lower part of the Globotruncana falsostuarti Zone. This stratigraphic level indicates that Globotruncana pseudoconica nov. sp. appears earlier in the Maastrichtian (for this studied section) than Globotruncana conica WHITE.
Globotruncana pseudoconica nov. sp. is the last member of the evolutionary trend of G. arca rugosa G. falsostuarti (double and single keeled) G. pseudoconica nov. sp. (double and single keeled). The affinity of the at least two last members of this trend, G. falsostuarti and G. pseudoconica nov. sp., can be shown by the appearance of transitional specimens.
Globotruncana conica WHITE as described by B.M. Funnell & alii (1969) is synonymous with G. pseudoconica nov. sp.. As mentioned above, I examined the hypotype of Globotruncana conica WHITE sensu B.M. Funnell & alii (1969) and found it to be identical to G. pseudoconica nov. sp.. The possession of a high spiral side, subpetaloid chambers and a second keel on the beginning of the final whorl by specimens of Globotruncana conica WHITE as described by P.A. Dupeuble (1969), indicate that the illustrated specimens belong to G. pseudoconica nov. sp. and not to G. conica WHITE.
Globotruncana falsostuarti as identified by D. Linares (1977) shows such test characters as a strongly convex spiral side, a flat umbilical side, subpetaloid and elongated chambers on the umbilical side which have a greater affinity to Globotruncana pseudoconica nov. sp. than Globotruncana falsostuarti, and for this reason these specimens are identified as Globotruncana pseudoconica nov. sp.
I was able to examine specimens of Globotruncana conica WHITE as described by J. Salaj (1980) and found them identical to the specimens of Globotruncana pseudoconica nov. sp.. They possess the same characters as my own specimens of Globotruncana pseudoconica nov. sp., and they also occur in the same geographical area (Tunisia).
OCCURRENCE. Globotruncana pseudoconica nov. sp. was earlier recorded and described as Globotruncana conica WHITE by B.M. Funnell & alii (1969) from the Abathomphalus mayaroensis Zone of the Galicia bank, West of Spain, by P.A. Dupeuble (1969) from the Upper Maastrichtian of eastern Aquitaine, southern France, by D. Linares (1977) from the Lower and lower Upper Maastrichtian in the Betica mountains, Spain, and finally from the Abathomphalus mayaroensis Subzone of the Enfidaville area by J. Salaj (1980). I observed this species as first appearing in the middle Lower Maastrichtian (middle part of the Globotruncana falsostuarti Zone) and found that it ranges throughout the middle and upper Lower Maastrichtian and the Upper Maastrichtian of section II. In section I this species occurs throughout the section (U. Maastrichtian).
MATERIAL. 154 specimens have been investigated.
STRATIGRAPHICALRANGE. Middle Lower Maastrichtian to the top of the Maastrichtian.
Emended by Solakius and Salaj (1985)
Solakius, N. (1982). Description of a new species, Globotruncana pseudoconica and remarks on its relation to Globotruncana conica White and Globotruncana falsostuarti Sigal. Geobios. 15: 873-889. gs :: :: Solakius, N. (1983a). A new planktic foraminiferal species from the Late Maastrichtian of Tunisia. Neues Jahrbuch für Geologie und Palaeontologie Monatshefte. 2: 113-118. gs :: ::
Solakius, N. (1982). Description of a new species, Globotruncana pseudoconica and remarks on its relation to Globotruncana conica White and Globotruncana falsostuarti Sigal. Geobios. 15: 873-889. gs :: ::
Solakius, N. (1983a). A new planktic foraminiferal species from the Late Maastrichtian of Tunisia. Neues Jahrbuch für Geologie und Palaeontologie Monatshefte. 2: 113-118. gs :: ::
Globotruncana pseudoconica compiled by the pforams@mikrotax project team viewed: 29-5-2020
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