GNS Science

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

New Zealand Cenozoic Mollusca

Neoguraleus (Fusiguraleus) flexicostatus Powell, 1942


(Pl. 22t): GS11154, J39/f26, foot of Mt Horrible, Pareora River, South Canterbury, Otaian (GNS)

Beu & Maxwell (1990): Chapter 11; p. 213; pl. 22 t.

Synonymy: Neoguraleus (Fusiguraleus) flexicostatus Powell 1942, p. 141

Classification: Conidae: Mangeliinae

Description: Size moderate for subfamily (height 9-11.5 mm), narrowly fusiform, spire half total height. Protoconch narrowly dome-shaped, of about 3 strongly convex whorls, first 1.5 whorls smooth, remainder with 4 or 5 spiral cords and axial costae, both increasing quickly in strength. Teleoconch of about 6 whorls, broadly shouldered at about 0.67 whorl height on spire, ramp almost flat, sides gently convex; last whorl strongly excavated with a moderately long, straight neck. Axial sculpture of prominent, slightly opisthocline costae, narrow on ramp, broader and more rounded below; almost straight and reaching from suture to suture on spire, distinctly flexuous on last whorl and dying out on lower part of base; 9-12 costae on penultimate whorl. Spiral sculpture weak, subobsolete to obsolete on spire, very subdued on base of last whorl, strongest on neck where it consists of closely spaced, narrow cords. Aperture narrow, columella weakly flexuous, siphonal canal short, unnotched. Outer lip thin, with shallow, U- shaped anal sinus on ramp.

Comparison: Neoguraleus flexicostatus is distinguished from most other species of N. (Fusiguraleus) by its relatively large size, its prominent, slightly flexuous axial costae, and its very weak spiral sculpture. N. (Fusiguraleus) major (Altonian, Ardgowan Shellbed, Oamaru) is most similar, but is considerably larger (height 15-16 mm) and has more weakly shouldered teleoconch whorls. The subgenus N. (Fusiguraleus) differs from Neoguraleus (sensu stricto) in having a much longer, less strongly twisted columella and, in most species, a more slender and more fusiform shell. It is first recorded from the Duntroonian (Shell Gully, Chatton), and apparently became very speciose during the Altonian — particularly in North Otago and South Canterbury — but is rather uncommon in younger beds. It is last recorded from the Haweran Te Piki bed, near East Cape, and so seems likely to be recognised in the living fauna of New Zealand. Most records of Fusiguraleus are from moderately shallow water faunules (inner to mid-shelf equivalent) but some, including N. (Fusiguraleus) flexicostatus, are from outer shelf or upper bathyal assemblages.

Distribution: Otaian; Pareora River (type — probably from Mount Harris Formation, foot of Mt Horrible); Bluecliffs, Otaio River, uncommon.

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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