Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
| | Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990) |
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  (Pl. 29i): GS5740, S27/f8622, Hurupi Stream, Palliser Bay, southern Wairarapa, early Tongaporutuan (GNS) |
Beu & Maxwell (1990): Chapter 13; p. 260; pl. 29 i.
Synonymy: Struthiolaria praenuntia Marwick 1926c, p. 318
Classification: Struthiolariidae
Description: Closely similar to S. calcar Hutton (Otaian-Waiauan) (Pl. 20g, h), differing in larger size and significantly taller, narrower shape of most specimens, in lacking, or having only weak, nodules around shoulder angle and, in particular, by developing median spiral cord on spire whorls. On a few specimens, median cord descends to last whorl, but on most specimens it fades out over penultimate whorl.
Comparison: The median cord is very variable in prominence in all populations of Struthiolaria praenuntia, although it appears to be more prominent in mid-Tongaporutuan than in early Tongaporutuan populations. It represents the strongest development of this median cord in mid-late Neogene species of Struthiolaria and, despite its subtlety, has proved reliable in biostratigraphy; all specimens we have seen with a prominent median cord are from Tongaporutuan rocks. It is succeeded again rapidly by forms such as S. nexa (Kapitean, Gisborne area) and S. cincta (Kapitean, Awatere Valley) that have again lost the median cord. (The relationship to Pelicaria nana is discussed under that species).
Distribution: Tongaporutuan; Tirangi Stream, near Tongaporutu, North Taranaki (type) and common in shallow-water shellbeds in Taranaki, Gisborne district, Wairarapa, and Canterbury. Found only in inner-mid shelf, soft-bottom facies.
Cite this publication as: "A.G. Beu and J.I. Raine (2009). Revised
descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990). GNS
Science miscellaneous series no. 27."
© GNS Science, 2009
ISBN
978-0-478-19705-1
ISSN 1177-2441
(Included with a PDF facsimile file
copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version
from: Publications Officer, GNS Science, P.O. Box 30368 Lower Hutt, New
Zealand)