Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 39a): GS2312, U22/f9488, Ashcott Road at foot of Pukeora Hill, near Waipukurau, Hawke's Bay, Nukumaruan (GNS)
(Pl. 39c): GS2312, U22/f9488, Ashcott Road at foot of Pukeora Hill, near Waipukurau, Hawke's Bay, Nukumaruan (GNS)
Beu & Maxwell (1990): Chapter 15; p. 310; pl. 39 a,c.
Synonymy: Pleuromeris hectori Powell 1938b, p. 160
Classification: Carditidae: Venericardiinae
Description: Very large for New Zealand members of the genus (12-24 mm high), subcircular, with only slightly protruding umbo slightly in front of centre. Sculpture of about 20-24 prominent radial costae; low and wide, with weakly convex crests, on most specimens; varying from very closely spaced, with only narrow grooves between (on largest specimens) to having flat-bottomed, almost smooth interspaces half the width of 1 costa. Commarginal sculpture of low, rounded, narrow, closely spaced ridges on the surface of each radial costa, crossing radial interspaces on most specimens. Lunule shallowly impressed, long and narrow on most specimens but becoming short, relatively wide, and steeply inclined beneath umbo of large specimens. Interior of ventral margin coarsely crenulate. Hinge short; with large, smooth, triangular median cardinal tooth, 2 cardinal sockets, and weak anterior lateral tooth and socket in right valve; 2 narrowly triangular cardinal teeth, large median pit, and very small anterior lateral tooth in left valve. Adductor muscle scars oval, subequal; pallial line without sinus.
Comparison: The taxonomy of New Zealand Pleuromeris species is poorly understood, and the status of Pleuromeris hectori and of the closely similar P. finlayi is in doubt. Small specimens in the same collections appear identical to the Castlecliffian and living P. zelandica whereas large specimens have lower, wider, and more closely spaced radial costae. It is possible that P. hectori is merely based on large specimens of P. zelandica, although it is more likely that they are distinct, as B. A. Marshall (NMNZ) reported that all these and several other species occur living around New Zealand.
Distribution: Mangapanian-Nukumaruan (- Castlecliffian, Recent?); Castlepoint, west Wairarapa coast, Nukumaruan (type); common in shallow-water coquina limestone and mudstone throughout New Zealand, wherever late Pliocene rocks are preserved.
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)