Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 15i): GS9806, F45/f9668, Shell Gully, Chatton, Duntroonian (GNS)
Beu & Maxwell (1990): Chapter 10; p. 158; pl. 15 i.
Synonymy: Natica (Magnatica) sutherlandi Marwick 1924d, p. 555; M. (Spelaenacca) altior Finlay 1926b, p. 228-229
Type species (as M. altior) of Spelaenacca Finlay, 1926
Classification: Naticidae: Naticinae
Description: Moderately large for family (height 32-42 mm), ovate, spire low, conic. Protoconch not clearly differentiated from teleoconch in available specimens. Teleoconch whorls rapidly expanding. No sculpture apart from growth lines. Aperture semilunular; inner lip thickened adapically by rounded circumumbilical ridge; parietal callus moderately thick. Umbilicus with a sharp-edged, step-like ridge within.
Comparison: Magnatica (Spelaenacca) sutherlandi is similar to M. planispira (see above), with which it occurs at both localities, but is taller-spired than most specimens of M. planispira, and has less rapidly expanding teleoconch whorls, lacking faint spiral sculpture, and has a sharp ridge well within the umbilicus. M. (Spelaenacca) parilis (Kaiatan, McCulloch's Bridge) is very similar to M. sutherlandi, but has a wider umbilicus and a more prominent intraumbilical ridge. Other named species of Spelaenacca are considerably smaller than M. sutherlandi or M. parilis.
Spelaenacca has a recorded range of Wangaloan to Clifdenian. Although it is ranked as a subgenus of Magnatica it is possible that the two taxa are not as closely related as this classification suggests.
Distribution: Duntroonian; Chatton Formation, Shell Gully, Chatton (type locality of N. sutherlandi) (not uncommon); Wharekuri Greensand, Wharekuri (type locality of M. altior) (uncommon).
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
(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)