Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 12a): GS9806, F45/f9668, Shell Gully, Chatton, Duntroonian (GNS)
(Pl. 12b): GS9806, F45/f9668, Shell Gully, Chatton, Duntroonian (GNS)
Beu & Maxwell (1990): Chapter 10; p. 145; pl. 12 a, b.
Synonymy: Ostrea wuellerstorfi Zittel 1864, p. 54; O. (Crenostrea) wuellerstorfi; Gigantostrea wuellerstorfi; Pycnodonte (Crenostrea) wuellerstorfi
Type species of Crenostrea Marwick, 1931
Classification: Gryphaeidae: Pycnodonteinae
Description: Moderately large for genus (height 100-160 mm), subequilateral to strongly oblique, left valve only moderately inflated, right valve considerably flatter. Shell composed of lamellar and vesicular layers. Sculpture mostly of irregular puckers and welts but also some more or less regular radial costae. Ligamental area rather small, not strongly projecting, with a broad, oblique resilifer. Chomata well developed, long and prominent, extending well down anterior and posterior margins, and all around margin on some specimens. Adductor muscle scar large, subcircular, behind middle of shell.
Comparison: Although this species has been recorded from numerous localities in the past, many of the records probably refer to other species, not all of them assignable to the Pycnodonteinae, let alone to Crenostrea. Some at least of the "giant" oysters in the Landon Series belong in the Ostreidae rather than the Gryphaeidae, probably in Flemingostrea (see below). As with most other oysters the distinctions between taxa are not always well defined, and as a consequence the group as a whole has been shunned by most paleontologists. C. wuellerstorfi is here restricted to species with a relatively small ligamental area that does not project strongly above the dorsal margin, with prominent chomata and with a large adductor muscle scar. The Early Eocene species C. cannoni (Pl. 3a, f) is more equilateral in shape, has a much larger and more strongly projecting ligamental area, much weaker chomata and a smaller adductor muscle scar than C. wuellerstorfi. C. gittosina (Otaian, Waiheke Island) seems to be very similar to C. wuellerstorfi and may not be distinct.
Distribution: Duntroonian-Waitakian; "Aotea Sandstone" (not the lower Whaingaroan Aotea Sandstone of the type locality), coast north of Whaingaroa (Raglan) Harbour, Southwest Auckland, Duntroonian (type); Chatton Formation, Shell Gully, Chatton.
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)