GNS Science

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

New Zealand Cenozoic Mollusca

Austrotoma lawsi Powell, 1942


(Pl. 22l): GS11283, J39/f9500C, Bluecliffs, Otaio River, South Canterbury, Otaian (GNS)

Beu & Maxwell (1990): Chapter 11; p. 208; pl. 22 l.

Synonymy: Austrotoma lawsi Powell 1942, p. 75

Classification: Turridae: Pseudotominae

Description: Size moderate for genus (height 25-40 mm), biconic, spire half total height. Protoconch of 4.5 whorls, last whorl with spiral cords, crossed on last quarter-whorl by axial costellae. Teleoconch of 5- 6 whorls, shouldered at or above middle on spire; sutural ramp concave, with prominent subsutural fold; last whorl broadly excavated, neck short and broad. Axial sculpture of narrow-crested costae extending from shoulder angle to lower suture on spire whorls and onto base on last whorl, in some shells becoming obsolete on later part of last whorl; 13-15 costae per whorl. Spiral sculpture of fine threads on ramp, one typically stronger than others on sub sutural fold; and narrow, rather crisp cords—some with interstitial threads—below, last whorl with 13-18 cords. Numerous growth lines weakly granulate the spiral cords and reticulate the threads. Aperture elongate, subrectangular; columella weakly twisted to left to form short, strongly notched siphonal canal; fasciole ridge- margined, more conspicuous on some shells than on others. Outer lip thin, with a shallow, arcuate sinus on ramp, well preserved shells with finely crenulate inner margin.

Comparison: Austrotoma lawsi seems to be most similar to A. clifdenica (Pl. 26e), but differs in having definite costae rather than only peripheral nodules on later whorls, and in having more numerous spiral cords on the last whorl.

Distribution: Otaian; Mount Harris Formation, Bluecliffs, Otaio River (type); foot of Mt Horrible, Pareora River; lower Tengawai River, moderately common. Powell's (1942, p. 75) record of this species from Awamoa Creek (Altonian) is based on a specimen of A. minor.

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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