Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 49n): GS4013, R22/f6353, Tainui Shellbed, Castlecliff, Wanganui, Castlecliffian (GNS)
Beu & Maxwell (1990): Chapter 16; p. 368; pl. 49 n.
Synonymy: Splendrillia annectens Powell 1942, p. 103
Description: Moderately large for genus (14-17 mm high), tall and narrow, with moderately tall spire (1.5 times height of aperture and canal), short, widely open anterior canal with shallow anterior notch and obscure fasciole, and spire strongly stepped because of prominent shoulder nodules, which commence abruptly below strongly concave sutural ramp; subsutural fold weakly developed or absent. Sculpture of many fine, low, closely spaced spiral threads over entire surface below sutural ramp (which is smooth except for growth lines), crossing prominent, rounded, closely spaced, short axial costae, about 15-16 per whorl. Aperture long and narrow, with thickened lips, prominent parietal tubercle, and prominent, spout-like, deep, U-shaped anal sinus occupying sutural ramp, with outer lip swinging well forward below; outer lip with very weak stromboid notch. Protoconch dome-shaped, of 1.5 low, smooth whorls.
Comparison: Splendrillia annectens is similar to the Recent species S. aoteana Finlay, but differs in its evenly and finely sculptured surface; S. aoteana has spiral sculpture on the neck only. The Nukumaruan species S. aequistriata (Pl. 42t) is considerably larger, with a longer last whorl, but otherwise similar. The other two species recorded from Castlecliff (S. edita, S. anomala) differ in their smaller size and weaker spiral sculpture, but are difficult to distinguish.
Distribution: Castlecliffian. "Blue clays, near base of Castlecliff beds, Wanganui", i.e., Kai-Iwi siltstone beds, Castlecliffian (type); occurs uncommonly in most siltstone beds in the Castlecliff section, but not known to us from elsewhere.
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)