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. 26l): GS11185, D45/f8822, Slip Point, Clifden, Clifdenian (GNS) |
Beu & Maxwell (1990): Chapter 11; p. 234; pl. 26 l.
Synonymy: Austrotoma echinata Powell 1942, p. 74
Classification: Turridae: Pseudotominae
Description: Small for genus (height 23-30 mm), biconic, spire half total height. Protoconch like that of A. clifdenica. Teleoconch of 5 whorls, sharply keeled at or near middle on spire, sutural ramp relatively broad, strongly concave with a subsutural fold of variable strength; last whorl weakly excavated. Axial sculpture of low, well spaced, rounded costae, reaching from shoulder keel to lower suture on spire, and across base of last whorl; 13-15 per whorl. Spiral sculpture of very fine threads on sutural ramp, and well spaced, narrow but prominent cords with fine interstitial threads below; 9 on last whorl, the lowest 3 considerably weaker than those above. Sharp tubercles formed at intersections of axial costae and spiral cords. Spiral threads finely reticulated by growth lines. Siphonal notch deep; fasciole prominent, sunken, margining ridge raised, sharp.
Comparison: Austrotoma echinata is one of the most distinctive species of the genus, distinguished by its small size, its squat shape and its prickly sculpture. Specimens from the Altonian-Clifdenian of Karamea district are very similar, but are more slender, have more closely spaced axial costae, and have smaller tubercles than Clifden shells — they may represent a species ancestral to A. echinata.
Distribution: Clifdenian-Lillburnian; Slip Point Siltstone, Slip Point, Clifden, Clifdenian (type), moderately common; Third Bay Sandstone, Clifden.
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)