Hedbergella sliteri Huber 1990 from: Huber, B.T. (1990): Maestrichtian planktonic foraminifer biostratigraphy of the Maud Rise (Weddell Sea, Antarctica): ODP Leg 113 Holes 689B and 690C. In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 113 Eds: Barker, P.F.Kennett, J.P.O'Connell, S.B.Pisias, N.G. p. 489-513 . |
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Species Hedbergella sliteri Huber 1990 |
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Diagnosis / Definition: |
Huber (1990):
Test nearly planispiral to low trochospiral, chambers gradually increasing in size, five to six in final whorl, umbilicus broad and shallow, aperture a low extra-umbilical arch bordered by a narrow porticus near the equatorial periphery. |
Discussion / Comments: |
Huber (1990):
Etymology: Named for W. V. Sliter (USGS, Menlo Park), a pioneer in the study of Late Cretaceous planktonic foraminifer biogeography of the southern South Atlantic.
Description: Test coiled in a low trochospire and sometimes nearly planispiral, often flattened on the spiral side, convex on the umbilical side, average diameter 273 /xm, average breadth 123 /xm. Chambers inflated, slightly reniform to globular, increasing gradually in size, usually
five to six in the final whorl, four and one-half to six in the penultimate whorl, 12 to 15 comprising the entire test of adult specimens, final chamber normalform or sometimes kummerform. Proloculus diameter averaging 17 /an, initial whorl diameter averaging 74 /un, with a mean of 5.0 chambers in the initial whorl. Sutures strongly depressed, radial
and straight on the spiral and umbilical sides. Umbilicus shallow, broad, averaging 28% of the maximum test diameter. Aperture a low, interiomarginal arch, extra-umbilical, sometimes positioned very near the equatorial periphery, bordered by a narrow porticus. Relict apertures and apertural flaps well-developed. Test surface nearly smooth to finely pustulose,outer wall radial hyaline, finely perforate.
Remarks: Populations of this species were compared with topotypes of H. monmouthensis (Olsson) from the Red Bank Formation (New Jersey) and SEM illustrations of H. holmdelensis Olsson and H. monmouthensis provided by R. K. Olsson (pers, comm., 1987). Hedbergella sliteri differs by its larger size, chambers that increase more gradually in size, fewer number of chambers in the penultimate whorl and broader umbilical region. The frequency of specimens with kummerform final chambers is higher among the Maud Rise assemblages than those of the Falkland Plateau. |
Synonym list: |
Huber (1990):
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Specimen: |
USNM, Inventory number: USNM 41770
USNM, Inventory number: USNM 41771
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References: |
Webb,P.N. (1973): Upper Cretaceous-Paleocene Foraminifera from Site 208 (Lord Howe Rise, Tasman Sea), DSDP, Leg 21. In: i Vol. 21 Eds: Burns, R.E.Andrews, J.E.et al. p. 541-573
Sliter,W.V. (1977): Cretaceous foraminifers from the southwestern Atlantic Ocean, Leg 36, Deep Sea Drilling Project. In: Initial Reports of the Deep Sea Drilling Project Vol. 36 Eds: Barker, P.F.Dalziel, E.W.D.Al, E. p. 519-573
Huber,B.T. (1988): Upper Campanian-Paleocene foraminifera from the James Ross Island region (Antarctic Peninsula). In: Geology and Paleontology of Seymour Island, Antarctica, Memoirs of the Geological Society of America Vol. 169 Eds: Feldmann, R.M..Woodburne, M.O.. p. 163-251
Huber,B.T. (1990): Maestrichtian planktonic foraminifer biostratigraphy of the Maud Rise (Weddell Sea, Antarctica): ODP Leg 113 Holes 689B and 690C. In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 113 Eds: Barker, P.F.Kennett, J.P.O'Connell, S.B.Pisias, N.G. p. 489-513
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