Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 37o): lectotype of Fulguraria morgani, "holotype" of Alcithoe gatesi, Waipipi Shellbeds, Waverley Beach, west of Wanganui, Waipipian (TM6822, GNS, ex Marshall and Murdoch Collection)
Beu & Maxwell (1990): Chapter 14; p. 300; pl. 37 o.
Synonymy: Fulguraria morgani Marshall & Murdoch 1920, p. 133 (not of Cossmann & Pissarro, 1905); Alcithoe gatesi Marwick 1926a, p. 302 (new name for Fulguraria morgani Marshall & Murdoch, preoccupied); Alcithoe (Leporemax) gatesi, Beu & Maxwell 1990, p. 300, pl. 37o.
Classification: Volutidae: Zidoninae
Description: Small for genus (45-55 mm high), tall and narrow, with spire 0.66 height of aperture; aperture widely open anteriorly, with deep, moderately wide anterior notch forming low, narrow fasciolar ridge. Spire outline clearly but relatively weakly stepped, with gently rounded shoulder angle but tall, steep, deeply concave sutural ramp; last whorl weakly inflated below shoulder and weakly contracted lower down, with outer lip parallel to left outline of shell or more strongly flared, thickened, and lightly reflected. Sculpture of narrowly crested, closely spaced axial costae, weak on sutural ramp but prominent from shoulder to base, about 20 per whorl. Inner lip lightly thickened, with 4 narrow columellar plaits. Protoconch as in A. fusus (Pl. 49i).
Comparison: Alcithoe gatesi was apparently the ancestor of the A. brevis-fusus lineage, in which costal prominence decreased fairly regularly. It possibly descended from such Late Miocene species as A. rugosa (Tongaporutuan), which has still more prominent costae. The apparently succeeding species A. brevis (Nukumaruan; Pl. 42m) has slightly less prominent axial costae and a more shallowly concave sutural ramp than A. gatesi, but the two are very similar, and the identity of Mangapanian specimens is unclear. The synonymy of Leporemax with Alcithoe is discussed under A. lepida (Pl. 21t).
Distribution: Waipipian (-Mangapanian?); Waipipi Shellbeds, Waverley Beach, west of Wanganui, Waipipian (type); fairly common in shallow-water sandstone and shellbeds along the Wanganui-South Taranaki coast; uncommon in shelf mudstone facies in the Wairoa and Dannevirke districts, Hawke's Bay.
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)