Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 4h): GS12139, CH/f104A, sea-cliffs near Waitangi radio station, Chatham Island, Waipawan (?) (GNS)
Beu & Maxwell (1990): Chapter 6; p. 89; pl. 4 h
Description: Small for family (height 12-22 mm), higher than long, left valve apparently somewhat more inflated than right. Anterior ears considerably larger than posterior ears, dorsal margins colinear; byssal notch moderately deep, fasciole depressed, ctenolium apparently absent. Disc with relatively prominent "Camptonectes" microsculpture of antimarginal, discontinuous and rather irregular grooves, typically absent from proximal and central areas on larger shells. Radial sculpture of very low, flattened costellae, typically appearing at 3-4 mm from umbo, but not obvious on figured specimen until about 18 mm, seemingly divaricating distally because of intersecting "Camptonectes" grooves. Radial costellae on ears considerably more prominent than those on disc. Commarginal sculpture of very fine threads.
Comparison: The new species is readily differentiated from most other New Zealand pectens by its small size, by its relatively prominent fine antimarginal microsculpture, and by having weak radial sculpture on the disc but more prominent radials on the ears. Eburneopecten(?) imperfectus (Marwick, 1928) (Waipawan, Tioriori, Chatham Island) is larger than the undescribed species (height of holotype, the only known specimen, 27 mm), is more circular in shape, has relatively strong radial sculpture on the left valve but only feeble striae on the right, and has smooth ears. Neither species seems to be closely related to any other known New Zealand pecten, and they were tentatively referred to Eburneopecten Conrad, 1865, which has been recorded previously from the Eocene and Oligocene of North America and Europe, by Beu & Maxwell (1990). However, Waller (2006, p. 14) showed that few species are correctly referred to Eburneopecten; he referred only North American Early to Middle Eocene species here. There is no doubt that the New Zealand species do not belong in Tribe Eburneopectinini Waller, 2006, and require a new genus, probably in Chlamydini. Waller's research has demonstrated the enormous diversity of Pectinidae, and much of its convergent evolution has still to be resolved.
Distribution: Waipawan(?), Red Bluff Tuff, sea-cliffs near radio station, Waitangi, Chatham Islands, not uncommon.
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)