Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 7t): GS9508, J40/f8803, McCulloch's Bridge, Kaiatan (GNS)
Beu & Maxwell (1990): Chapter 8; p. 119; pl. 7 t.
Classification: Ranellidae: Cymatiinae
Description: Size moderate for subgenus (height 30-33 mm), tall and rather narrow, spire half total height. Protoconch small, dome-shaped, of 2.5 smooth whorls. Teleoconch whorls strongly angled a little above middle on spire, last whorl broadly excavated with a moderately long, slightly twisted neck. Axial sculpture of high, narrowly rounded, closely spaced costae, and at intervals of 0.67 whorl, prominent, narrow, rounded varices down whole teleoconch. Costae reaching across base of last whorl. Spiral sculpture of prominent, fairly wide, round-topped, well spaced cords, 2 on sutural ramp, 2 or 3 on sides of spire whorls, and 10 more on base and neck of last whorl, with narrow threads in interspaces. Cords forming prominent, narrow nodules where they cross axial costae and varices. Aperture oval; siphonal canal moderately long, slightly twisted dorsally. Inner lip narrowly and thinly callused with a minute pseudumbilicus between its abapical end and canal, a large parietal ridge and several transverse ridges and nodules on mid-lower columella. Outer lip weakly flared over terminal varix, with raised outer rim and 6 prominent, narrow nodules on its inner edge.
Comparison: This coarsely sculptured species represents a very different species group from those of most other New Zealand Sassia, and has no known younger relatives. The group of S. maoria (PI. 20o) and S. parkinsonia (PI. 48f) is represented at McCulloch's Bridge (and other Kaiatan and Runangan localities) by S. cyphoides, a weakly sculptured species in which spiral cords are the dominant sculpture. The groups of S. zealta (PI. 241), Haurokoa woodi (PI. 30b) and S. clifdenensis (PI. 24n) are also all represented at McCulloch's Bridge, mostly by unnamed species (but see Haurokoa marwicki, below). The unnamed species described here more nearly resembles some of the European fossil Sassia species and the living S. apenninica (Sassi, 1827) species group than other New Zealand fossil species but it has the same smooth, dome-shaped protoconch as most other Sassia species, including the New Zealand species placed by Finlay in Austrosassia, rather than the coarsely cancellate protoconch of the S. apenninica group.
Distribution: Kaiatan, Waihao Greensand, McCulloch's Bridge (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
(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)