Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 20o): GS11283, J39/f9500C, Bluecliffs, Otaio River, Otaian (GNS)
Beu & Maxwell (1990): Chapter 11; p. 194; pl. 20 o.
Synonymy: Austrotriton maorium Finlay 1924b, p. 453; A. maorium var. insignitum Finlay 1924b, p. 454; Austrosassia maoria; A. insignita; Sassia (Sassia) maoria, Beu & Maxwell 1990, p. 194, pl. 20o.
Classification: Ranellidae: Cymatiinae
Description: Small for genus (height 25-37 mm), with moderately tall, weakly stepped spire (a little less than half total height in well preserved specimens with long canal). Protoconch as in S. parkinsonia (Pl. 48f), turbiniform, of 2.5 smooth whorls. Teleoconch whorls 4-5, shouldered near middle on spire, last whorl with prominent peribasal angulation, base convex, rapidly contracted to moderately long neck. Low, narrow varices with hollowed back (abapertural) faces at each 0.67 whorl down whole teleoconch; varices retracting to suture rather than crossing it. Sculpture of 2 major spiral cords on spire whorls and 2 more on base of last whorl, low, narrow and widely spaced, bearing low nodules (particularly on uppermost cord) where they cross the low, rounded axial costae; remainder of surface (including spaces between primary cords) closely sculptured with low, narrow, irregularly gemmate spiral threads and faint growth ridges. Aperture small, subcircular with long to moderately long, straight, weakly left-deflected siphonal canal; outer lip flared, bearing 5 prominent nodules on inner edge; inner lip narrowly flared with low parietal callus and a few ridges on base of columella.
Comparison: Sassia maoria is the most common New Zealand Oligocene and Early Miocene ranellid, recognisable by its relatively short spire, its almost circular aperture, and its relatively long canal. The varices do not clasp the preceding whorl, as they do in S. pahaoaensis (Clifdenian-Tongaporutuan), which succeeds S. maoria at Clifden. The S. maoria-S. parkinsonia species group is discussed under S. parkinsonia, below.
Distribution: Duntroonian-Altonian; Target Gully Shellbed, Oamaru, Altonian (type locality of both A. maorium and its "variety" insignitum), and many localities in North Otago, Canterbury and Southland.
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
(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)