Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 8aa): McCulloch's Bridge, Kaiatan (Canterbury Museum)
Beu & Maxwell (1990): Chapter 8; p. 128; pl. 8 aa.
Synonymy: Triploca waihaoensis Marshall & Murdoch 1923a, p. 128
Description: Size moderate for family (height c.10 mm), ovate, spire a little more than half total height. Protoconch of about 2 smooth whorls, initial whorl depressed. Teleoconch of 5 whorls, those on spire gently convex with a narrow sutural shelf; last whorl large, evenly convex with a small pseudumbilicus. Spiral sculpture of fine grooves with broad, flat interspaces, 6-7 on penultimate whorl, an additional 16 on base of last whorl. Axial sculpture of very fine growth lines restricted to grooves. Aperture ovate, columella short, sub-vertical with 3 strong, rather sharp plaits, the adapical one the strongest. Inner lip thinly callused; outer lip apparently thin, opisthocline, with shallow spiral grooves within.
Comparison: Triploca waihaoensis is distinguished from other New Zealand acteonids by its relatively tall spire and, most importantly, by the presence of three columellar plaits. T. waihaoensis is very similar to the type species, T. ligata Tate, 1894 (Late Eocene, South Australia) and is possibly conspecific. The only other New Zealand record of the genus is from the Mangaorapan of White's Creek, North Canterbury.
Distribution: Kaiatan, Waihao Greensand, McCulloch's Bridge (type) (rare).
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)