Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 8l): GS9480, J40/f8801, McCulloch's Bridge, Kaiatan (GNS)
Beu & Maxwell (1990): Chapter 8; p. 126; pl. 8 l.
Synonymy: Surcula marginalis Marshall 1919, p. 231-232; S. equispiralis Marshall 1919, p. 232; S. hampdenensis Marshall and Murdoch 1920, p. 134
Classification: Turridae: Zemacieinae?
Description: Moderately large for subfamily (height 40- 80 mm), fusiform, spire half total height. Protoconch narrowly conical, of about 4 smooth whorls. Teleoconch of 7 or 8 whorls, obtusely angled somewhat above middle on spire; sutural ramp slightly concave, with a weak subsutural swelling; last whorl weakly excavated, tapering to a moderately long neck. Axial sculpture consisting of narrow, strongly opisthocline costae reaching from shoulder to lower suture on early whorls, but becoming restricted to peripheral nodules on later whorls (12-15 on penultimate whorl), eventually becoming obsolete on largest shells. Spiral sculpture consisting of a single narrow cord on subsutural swelling, a few weak threads between it and shoulder, and rather subdued, low, rounded cords below shoulder. Aperture narrow, with a moderately long, narrow siphonal canal. Inner lip only thinly glazed; outer lip thin with a deep, tongue-shaped anal sinus, its apex near middle of ramp.
Comparison: Zemacies elatior (Pl. 26i) resembles Z. marginalis in having a narrow cord near the upper suture, but differs in having finer spiral sculpture, and axial sculpture of short, opisthocline ridges extending a short distance below the periphery (confined to early whorls on many shells).
Zemacies has a recorded range of Wangaloan to Waipipian in New Zealand (although there are no records from the Taranaki Series), and is also present in the mid-Cenozoic of Victoria, Australia. Fossils seems to have had a mid-shelf to upper bathyal habitat. Several species are now assigned to Zemacies in the Recent fauna (e.g., "Leucosyrinx" queenslandicus Powell, 1969 & Z. excelsa Sysoev & Bouchet; Sysoev & Bouchet 2001, p. 283) where they are recorded from the Southwest Pacific in depths of 46-230 m (Z. queenslandica) and 240-680 m (Z. excelsa).
Distribution: Bortonian-Kaiatan; Bortonian, Hampden Formation, Hampden Beach (type locality of all three nominal species); Waihao Greensand, McCulloch's Bridge. Uncommon at both 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)