GNS Science

Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)

New Zealand Cenozoic Mollusca

Marshallena curtata (Marwick, 1926)


(Pl. 27r): holotype, GS1141, Q18/f8493, coast south of mouth of Wai-iti Stream, North Taranaki, Tongaporutuan (TM 5606, GNS)

Beu & Maxwell (1990): Chapter 12; p. 250; pl. 27 r.

Synonymy: Turricula curtata Marwick 1926c, p. 325

Classification: Turridae: Pseudotominae

Description: Moderate-sized for genus (height c. 20 mm), broadly fusiform, spire 0.45 total height. Protoconch bluntly conical, of about 3 whorls; last quarter-whorl with narrow axial costellae, remainder smooth. Teleoconch of 4-4.5 whorls, somewhat glazed, sharply angled at or slightly below middle on spire whorls, last whorl broadly excavated with a short neck. Axial sculpture of narrow, rather sharp-crested costae with concave interspaces, reaching from shoulder angle to lower suture on spire and dying out over upper part of base on last whorl; 15-18 on penultimate whorl. Sutural ramp bearing a row of weak nodules corresponding to costae, bordering suture. Spiral sculpture commencing as 2 weak cords, 1 on shoulder, the other between shoulder and lower suture; additional cords appearing during growth, adult whorls covered with closely spaced, flattened cords and interstitial threads, those on sutural ramp noticeably weaker than those below. Penultimate whorl with 4 or 5 cords below shoulder; last whorl with 12-16 additional cords, some with interstitial threads, on base and neck, becoming crowded anteriorly. Peripheral cord slightly thickened where it crosses costae, other cords virtually unaffected. Aperture pyriform, siphonal canal short, slightly oblique; columella gently convex. Outer lip with shallowly arcuate anal sinus, its apex closer to suture than to periphery.

Comparison: Marshallena curtata differs from M. neozelanica (Pl. 8v) — the only other named New Zealand species considered to belong in the genus — in its less elongate shape and in having more sharply shouldered teleoconch whorls and stronger axial sculpture. Its closest relative is a very rare, undescribed species from the Mount Harris Formation at Pareora River, South Canterbury (Otaian), which differs primarily in having a flattened apex to the protoconch.

Marshallena curtata occurs only in bathyal siltstone in both North Taranaki and southern Wairarapa, and the Recent Indo-West Pacific species referred to Marshallena by Powell (1969) are recorded from the upper bathyal zone only. However, the other New Zealand "Marshallena" species (see discussion under M. neozelanica), referred now to Zeatoma, occur in inner to outer shelf faunules.

Distribution: Tongaporutuan; coast south of Wai-iti Stream, North Taranaki (type); also Bell's Creek and nearby tributaries of Mangaopari Stream, southern Wairarapa.

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)


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