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. 26p): Pakaurangi Member, Pakaurangi Point, Kaipara Harbour, Altonian (GNS, ex Marshall and Murdoch Colln.) |
Beu & Maxwell (1990): Chapter 11; p. 238; pl. 26 p.
Synonymy: Cylichnania bartrumi Marwick 1931, p. 153
Type species of Cylichnania Marwick, 1931
Classification: Cylichnidae
Description: Size moderate for family (height 6.5-11.5 mm), cylindrical, involute, apex with deep depression. Axial sculpture of fine growth lines, typically best-developed between spirals near posterior end. Spiral sculpture of numerous, very low, flat-topped cords of variable width; interspaces linear over most of length, considerably wider near posterior end and more so near anterior end. Aperture narrow over most of its length, wider anteriorly, columella very short, subvertical, with a weak but definite oblique fold near middle. Inner lip moderately callused over columella, forming a narrow pseudumbilical chink; thinly callused above. Outer lip thin, subparallel to inner lip over much of its length, edge finely crenulate; prosocline anteriorly, almost straight and orthocline above, extending well above posterior end of inner lip.
Comparison: Cylichnania is recognisable by its subcylindrical shape, its sculpture of even, low, flat-topped spiral cords, and its deep apical depression, with the outer lip extending well posteriorly to the inner lip. Distinct species occur in the Altonian of Oamaru district and at Clifden. Cylichnania appears to be endemic to New Zealand, where it ranges from Wangaloan to at least Tongaporutuan, and possibly to Opoitian. Records indicate a mid-shelf to upper bathyal habitat.
Distribution: Otaian-Altonian; Pakaurangi Formation, Pakaurangi Point, Kaipara Harbour (type, probably from the Altonian Pakaurangi Member where it is common); Paratoetoe Formation, north shore, Parengarenga Harbour. Also recorded by Marwick (1931, p. 154) from the Clifdenian and Lillburnian of Gisborne district, but specimens are not well enough preserved to confirm the identification.
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
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copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version
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Zealand)