Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 53f): Argalista kaiparaensis Finlay, 1930; topotype, GS9730, Q8/f9828, Holland's Pt, Pakaurangi, Kaipara Harbour (Otaian)
(Pl. 53i): Argalista kaiparaensis Finlay, 1930; topotype, GS9730, Q8/f9828, Holland's Pt, Pakaurangi, Kaipara Harbour (Otaian)
Beu & Maxwell (1990): Chapter 17; p. 378; pl. 53 f,i.
Description: Diameter 1.4-3.5 mm, depressed-turbiniform, rather solid, spire almost flat in some species, dome-shaped in others, non-umbilicate to widely umbilicate. Some species smooth but most with spiral sculpture of low, rounded cords or prominent keels; axial sculpture typically absent, but represented by crenulations on umbilical border on some species. Aperture circular, peristome interrupted. Operculum discoidal, calcareous, occasionally found fossil.
Comparison: A considerable number of species of Argalista has been described from New Zealand, but some may be difficult to distinguish from one another unless well preserved material is available. Although Argalista has been considered to be a subgenus of Homalopoma Carpenter, 1864 by some authors (e.g. Keen in Moore 1960, p. 1270; Fleming 1966b, p. 40; Powell 1979, p. 67) it differs from Homalopoma in its much smaller size, in the absence of obvious nacre, and in having a calcareous operculum rather than one with both shelly and horny layers it was returned again to generic rank by Beu & Maxwell (1990).
Distribution: Kaiatan-Recent, New Zealand; Recent, Australia. Mostly shallow-water, but extending down into the upper bathyal zone.
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)