Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 27p): GS3840, N34/f6222, Glenafric, mouth of Dovedale Stream, North Canterbury, Waiauan (GNS)
Beu & Maxwell (1990): Chapter 12; p. 249; pl. 27 p.
Synonymy: Mauia insignis Marwick 1926a, p. 274
Type species of Mauithoe Finlay, 1930
Classification: Volutidae: Zidoninae
Description: Small for family and wide (38 x 23 mm; but a few individuals reach 70 mm high), with low conic spire, weakly concave sutural ramp, relatively short, inflated last whorl, and very prominent sculpture. Sculpture of narrowly crested, closely spaced axial costae, 20-22 per whorl, extending well down last whorl and persisting to end of last whorl on almost all specimens; crossed by few faint spiral threads. Outer lip smooth, strongly thickened, produced into wide, greatly thickened flare in a few large individuals. Inner lip a thin glaze not masking sculpture of previous whorl, bearing 5 prominent columellar plaits on most specimens, but uppermost plait weak on a few specimens. Anterior end widely but shallowly notched, producing fasciole that is not raised above remainder of surface but is clearly bounded by line (a low ridge on some specimens). Protoconch large, strongly protruding, wide, of at least 2 low, apparently smooth whorls, but incomplete on all available material.
Comparison: Most specimens of Mauithoe insignis are markedly shorter and wider than Marwick's holotype (which, however, lacks the outer lip); a single very large shell from Glenafric shows that large, old shells develop a very wide, thick outer lip. The common short, wide form (illustrated) closely resembles the Tongaporutuan M. strongi (Gisborne district, type; Bell's Creek, South Wairarapa; Hurunui River, North Canterbury), which differs in having shorter, weaker, closer and more numerous axial costae. These two species appear to be closely related phylogenetically and to constitute a brief, minor offshoot of Alcithoe (of highly dubious generic rank), but the other two species included in Mauithoe by Finlay (1930d, p. 252) (Alcithoe parva, = A. propearabicula Bartrum and Powell, 1928; Opoitian, Kaawa Creek, southwest Auckland; and A. dilatata, Tongaporutuan, "Hurupi facies" shallow-water faunules in South Wairarapa) only superficially resemble M. insignis; we include them in Alcithoe (Alcithoe).
Distribution: Waiauan; not uncommon at the type locality, Glenafric, mouth of Dovedale Stream, North Canterbury, and a few specimens known from bathyal siltstone in the Gisborne district.
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)