Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
| | Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990) |
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  (Pl. 26i): GS10365, D45/f8598, Long Beach Shellbed, Clifden, Altonian (GNS) |
Beu & Maxwell (1990): Chapter 11; p. 236; pl. 26 i.
Synonymy: Zemacies elatior Finlay 1926b, p. 252
Type species of Zemacies Finlay, 1926
Classification: Turridae: Zemacieinae?
Description: Rather large for family (height 55-100 mm), narrowly fusiform, spire about half total height. Protoconch narrowly conical, of about 4 strongly convex, smooth whorls. Teleoconch of 8-10 whorls, bluntly shouldered somewhat above middle on spire; last whorl with weak basal subangulation, below which it is drawn out into a long, slender neck; sutural ramp concave, typically with a low subsutural swelling. Axial sculpture of small nodules on shoulder angle of early whorls, some shells with short, strongly opisthocline, ill-defined costae on periphery of later spire whorls. Spiral sculpture of a few weak threads on ramp, most shells with a considerably more prominent one on subsutural swelling; and narrow, low, rounded cords below, becoming obsolete on lower part of neck. Aperture narrow, elongate, with a long, slender, unnotched siphonal canal. Columella long, almost straight; inner lip thinly callused; outer lip thin with a deep, rounded anal sinus, its apex near middle of ramp, smooth within.
Comparison: This very elegant turrid is distinguished from other species of the genus by its slender shape and bluntly shouldered teleoconch whorls, and in having axial sculpture normally absent from all but the earliest teleoconch whorls. Z. lividorupis (Otaian, Bluecliffs and Pareora River, South Canterbury) is very similar, but has distinct axial sculpture persisting to a much later stage of growth. Specimens recorded from Ardgowan Shellbed (Altonian) as Zemacies elatior (Laws 1935c, p.34) are badly worn and could be Z. lividorupis rather than Z. elatior. Although Z. elatior is quite common in the early Altonian siltstone at Parengarenga Harbour, it is not recorded from beds of similar age at Pakaurangi Point, where another species, Z. ordinaria occurs; this differs from Z. elatior in having more strongly shouldered teleoconch whorls and more prominent peripheral nodules. As noted under Z. marginalis, similar species to Z. elatior are now known to be living in the Southwest Pacific on the mid- to outer shelf and in the upper bathyal zone.
Distribution: Altonian-Clifdenian; Fouraye Siltstone, Clifden, Altonian (type); Long Beach Shellbed and Slip Point Siltstone, Clifden; Paratoetoe Formation, Paratoetoe and Te Pokere, Parengarenga Harbour; ? Ardgowan Shellbed, Oamaru.
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)