Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 7o): GS9481, J41/f8025, Lorne,' Kaiatan (GNS)
(Pl. 7p): GS9481, J41/f8025, Lorne,' Kaiatan (GNS)
Beu & Maxwell (1990): Chapter 8; p. 118; pl. 7 o, p.
Synonymy: Trivia pinguior Marwick 1926b, p. 314; Pusula (Ellatrivia) pinguior; Fossatrivia pinguior; Ellatrivia pinguior
Classification: Triviidae: Triviinae
Description: Rather small for family (height 6- 7.5 mm), ovate, spire visible as a low swelling, dorsum with a weak median longitudinal sulcus. Transverse sculpture of about 20 narrow costae, well developed on some shells, almost obsolete' (particularly on dorsum) on others. Some costae continuous across dorsum, others appearing towards margins by bifurcation or intercalation. Aperture rather narrow, gently curved, inner and outer lips almost parallel, their margins denticulated by transverse ribs. Inner lip ridge-like adapically and abapically. Columella traversed by transverse costae, gently convex except for slightly concave fossula at abapical end.
Comparison: Trivia kaiparaensis (Otaian, Pakaurangi Point, Northland) is very similar to T. pinguior but has weak intercostal axial costellae on the dorsum near the outer lip. Both species are sufficiently similar to the type species of Trivia (T. monacha (Costa, 1778); Recent, Europe) to make assignment to other genera unwarranted. Triviines occur rather sporadically throughout the New Zealand Cenozoic from at least Kaiatan onwards, and their presence in a faunule is probably indicative of at least warm-temperate conditions. (The sole extant New Zealand species, T. merces, is confined to the northern half of the North Island). Although long considered as being closely related to the superficially similar Cypraeidae ("cowries"), the Triviidae are now regarded as belonging in the Lamellarioidea rather than the Cypraeoidea, i.e. the similarity between the two groups is the result of convergence. The generic classification of triviines is contentious, each authority using a different combination of genera and, although Dolin (2001, p. 118) referred T. kaiparaensis to Niveria (Ellatrivia), we adopt a conservative classification and retain New Zealand fossil species in Trivia.
Distribution: Kaiatan-Runangan, Waiareka Volcanic Formation, Lorne (type); McCulloch's Bridge(?); Trig M, Totara. Rather uncommon at listed localities.
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)