GNS Science

Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)

New Zealand Cenozoic Mollusca

Fissidentalium n. sp.


(Pl. 15o): GS476, I40/f9379, Waitaki River, opposite Wharekuri, Duntroonian (GNS)

Beu & Maxwell (1990): Chapter 10; p. 164; pl. 15 o.

Classification: Dentaliidae

Description: Large for family (length 100-150 mm), thick-shelled except near aperture, distinctly curved proximally but almost straight over most of its length. Well preserved shells with narrow apical slit. Longitudinal sculpture commencing as narrow, rounded or subtriangular costae which are soon joined by secondary costellae, all tending to become subequal, broader, lower and more flattened during growth, in some large specimens becoming obsolete near aperture; about 45 costae on mature shells. Well preserved shells with numerous very fine longitudinal threads between and on costae. Transverse sculpture of numerous, closely spaced fine ridges that cross longitudinal costae unchanged, quite distinct on early part of shell but gradually becoming subobsolete distally.

Comparison: Shells of this type have been recorded from numerous localities, ranging in age from Duntroonian to Tongaporutuan, as "Dentalium solidum Hutton, 1873", but several distinct species seem to be involved. The lectotype of D. solidum is from "Waikari", North Canterbury, and is probably of Tongaporutuan age; probable topotypes differ from the Wharekuri species in having much weaker transverse sculpture

Distribution: Duntroonian, Wharekuri Greensand, Wharekuri; head of Lake Waitaki.

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)


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