Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 30n): GS4799, J39/f6468, White Rock River, South Canterbury, Altonian (GNS)
Beu & Maxwell (1990): Chapter 13; p. 269; pl. 30 n.
Synonymy: Terebra orycta Suter 1913b, p. 295; Acuminia orycta
Description: Moderate-sized for genus (38-50 mm high), very tall and slender, relatively weakly sculptured, with large, elongate last whorl, almost straight columella and short, weakly twisted, widely open, deeply notched anterior canal bearing low fasciole bounded by very prominent, narrow spiral ridge. Protoconch small, narrowly conical. Teleoconch whorls slightly swollen below suture to produce weak subsutural fold occupying about upper 0.4 of spire whorls; in some specimens, lower boundary of fold is marked by a faint spiral groove. Lower 0.6 of spire whorls and central third of last whorl weakly concave, weakly sculptured; a low, in many specimens weakly defined, spiral cord at base of concave zone unites apices of low, narrow, axially elongate nodules, forming a further weakly convex zone around basal angulation of last whorl; nodules fade out rapidly to leave neck smooth. Similar low, narrow, widely spaced, axially elongate nodules around subsutural fold are linked, in some specimens, to basal nodules by very low, narrow axial costae over concave zone, but large specimens from the type locality are smooth medially.
Comparison: Specimens from Target Gully Shellbed and White Rock River appear not to reach the same size as Waiauan-Tongaporutuan ones, and at least some are slightly narrower and slightly more prominently sculptured than the younger specimens, but the differences do not seem to be significant. The low axial sculpture, the medially concave zone between two weakly convex zones, and the moderately stout form distinguish Zeacuminia orycta from the several other mid-Tertiary species. All localities are in near-shore sandstone and shellbeds, and Zeacuminia evidently lived in the same situation at modern Terebra, crawling only just covered in sand in lagoons and in the wave zone of sand beaches. The status of the "New Zealand" genus Zeacuminia is unknown, and species of this group require much further study, but they are difficult to classify into genera world-wide.
Distribution: Altonian-Tongaporutuan; Double Corner Shellbeds, Lower Waipara Gorge, North Canterbury, Waiauan (type); common at a few localities only: Target Gully Shellbed, Oamaru (Altonian), White Rock River, South Canterbury (Altonian), Double Corner Shellbeds and a few nearby localities in North Canterbury (Waiauan), and a few Tongaporutuan localities in North Canterbury and southern Wairarapa (mainly Hurupi Stream area, Palliser Bay).
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)