Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 47f): Landguard Sand, Landguard Bluff, east of mouth of Wanganui River, Castlecliffian (GNS, from old collection)
Beu & Maxwell (1990): Chapter 16; p. 350; pl. 47 f.
Synonymy: Turritella (Haustator) vittata Hutton 1873a, p. 29; Turritella carlottae Watson 1881, p. 222
Type species of Zeacolpus Finlay, 1926
Description: Moderate-sized for family (60-80 mm high), tall and slender, with 15-18 almost flat-sided whorls and very little-indented suture, a prominent peribasal angulation, and a subquadrate aperture with thin lips. Protoconch of 1 unusually tall whorl, partly uncoiled, with exsert apex. First 2-3 teleoconch whorls strongly convex, gradually developing primary spiral cords in order B, then C, then A; A is low and narrow, and is rivalled in prominence by gradually developing intermediate cords. Lower down the shell, B descends the whorl, so B-C interspace is narrower than A-B, and intermediate cords strengthen. On last 4-5 whorls, many fine spiral cords are subequal in prominence, producing a slightly outward-sloping subsutural zone with even, weak sculpture, wide, very slightly concave, mid-whorl zone with 6 subequal cords, and a narrow basal zone that contracts again slightly to suture. All main cords bright tan on cream ground on modern shells; colour pattern remains on some shells from Castlecliff. Outer lip with deep, wide, V-shaped sinus; wide, shallow sinus occupies base.
Comparison: Zeacolpus vittatus has a markedly narrower spire angle, slightly more prominent spiral cords, and a smaller protoconch of fewer whorls than the more abundant, partly sympatric species Maoricolpus roseus. M. roseus is much more common than Z. vittatus today in very shallow water (e.g., M. roseus is intertidal in Manukau Harbour, Auckland) and Z. vittatus is the more common on the shelf, in depths of about 5-50 m. Typical Z. vittatus occurs only in Mangapanian-Recent faunas. Ancestral forms in Opoitian and Waipipian rocks vary greatly in the prominence of the spiral cords; some were included by Marwick (1971a, p. 18) in Z. vittatus, whereas forms with more prominent cords were included in Z. opoitius opoitius (Opoitian) and Z. opoitius takapauensis (Waipipian). The species group apparently descended from the very coarsely sculptured Z. kanieriensis (Kapitean-Waipipian?, Westland; Pl. 36n).
Fleming (in Marwick 1971b, p. 67, footnote) recorded an ovoviviparous modern specimen of Maoricolpus roseus, and Marwick (1971b) recorded an ovoviviparous fossil specimen of Zeacolpus taranakiensis, so it seems likely that most or all New Zealand turritellids of at least Miocene to Recent age are ovoviviparous. The lack of a dispersive larval stage should be expected to produce highly variable species, explaining a lot of the problems paleontologists have had identifying and classifying turritellids.
Distribution: Opoitian-Recent; Recent, New Zealand (types of T. vittata and T. carlottae). Extremely widespread and abundant in a variety of shallow-water, soft-bottom facies throughout New Zealand.
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)