Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 7c): GS9508, J40/f8803, McCulloch's Bridge, Kaiatan (GNS)
(Pl. 7d): GS9508, J40/f8803, McCulloch's Bridge, Kaiatan (GNS)
Beu & Maxwell (1990): Chapter 8; p. 114; pl. 7 c, d.
Synonymy: Limopsis waihaoensis Allan 1926, p. 346
Description: Small for genus (height 7-11 mm), oval, slightly oblique, thin-shelled. Dorsal margins straight, subequal, or posterior one slightly the longer, sloping gently from small umbo. Anterior and ventral margins convex, junction with slightly convex posterior margin rounded or obtusely subangled. Commarginal sculpture of weak grooves and ridges. Radial sculpture also weak, strongest near posterior end, of indistinct threads that are typically visible only where they weakly crenulate the commarginal ridges. Exterior with an overall polished appearance. Hinge narrow, assymetrical, arched or subangled behind beak, 5 or 6 teeth in both anterior and posterior series. Cardinal area long, narrow, with fine longitudinal ridges; resilifer small, triangular. Anterior adductor muscle scar ovate, at lower end of hinge; myophoric ridge weakly to strongly developed. Posterior scar twice as large, ovate to subquadrate. Inner margins sharply bevelled, smooth.
Comparison: Limopsis waihaoensis is easily distinguished from most other New Zealand species of Limopsis by its small size and its feeble sculpture. L. propeinvalida (Otaian, Pakaurangi Point, Northland) and L. invalida (Waipipian, Pitt Island) are very similar, however, and are distinguished only by minor shape and sculptural differences. All three species are from moderately deep-water (outer shelf or upper slope) assemblages. The comparisons by Beu (2006, pp. 178-186) indicate that the other late Neogene-Recent deep-water species L. marwicki Powell, 1938 (early Nukumaruan, Castlepoint), L. peteri Beu 1969 (early Nukumaruan, South Wairarapa), L. turnbulli Beu, 2006 (Castlecliffian, Wilson River, SW Fiordland), and L. lata (E. A. Smith, 1885) and L. tasmani (Dell, 1956) (both Recent New Zealand bathyal fauna) are also all very similar to L. waihaoensis and L. invalida, differing only in minor characters of the shape, shell thickness, hinge length, and marginal crenulations.
Distribution: Kaiatan- Runangan; Kaiatan, Waihao Greensand, McCulloch's Bridge (type); Totara Limestone, Trig M, Totara; Oamaru Diatomite. Abundant at McCulloch's Bridge, uncommon at other 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)