Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 21f): GS9685, J41/f9499B, Pukeuri road cutting, Oamaru, Altonian (GNS)
Beu & Maxwell (1990): Chapter 11; p. 202; pl. 21 f.
Synonymy: Zemitrella haroldi Laws 1935, p. 40
Description: Rather small for family (height 5-5.5 mm), elongate-ovate, spire narrowly conical, 0.6 total height. Protoconch mamillate, of about 2 smooth, weakly convex whorls. Teleoconch of 4 whorls, spire whorls weakly convex; last whorl with rounded or subangled periphery, excavated below; sutures distinctly impressed. Spire whorls devoid of sculpture except for very feeble spiral striae; neck of last whorl with about 8 low cords. Aperture rather small, pyriform; columella twisted to left near middle to form -a short, slightly oblique, unnotched siphonal canal. Outer lip with a low, broad, rounded varix, bearing about 4 narrow lirae within.
Comparison: Zemitrella haroldi is distinguished from other species of Zemitrella by its almost straight-sided spire, its subangled periphery and its relatively prominent outer lip lirae. Although the modern New Zealand columbellid fauna is quite diverse (about 50 named species-group taxa) there are remarkably few records of the family prior to the Pliocene, suggesting either that its diversification has taken place relatively recently, or that one of its main habitats (intertidal to shallow subtidal algae on rocky shores) has a poor fossil record. Zemitrella itself is first recorded definitely from the Duntroonian, Z. mackayi (Bortonian-Kaiatan) being referred now to Bastropia (Maxwell 1992, p. 130).
Distribution: Altonian; Mount Harris Formation, Pukeuri road cutting, Oamaru (type); Awamoa Creek; Old Rifle Butts, Cape Wanbrow; excavation for Oamaru Borough Council septic tank, South Oamaru. Moderately common at Pukeuri, uncommon at other localities.
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)