Mesopeplum dendyi (Hutton, 1902)
HUTTON, F. W. 1902. On a new fossil Pecten from the Chatham Islands. Transactions and Proceedings of the New Zealand Institute, 34: 196 [p. 196, pl. 8]
1902 Pecten dendyi Hutton, 1902
F. W. Hutton, 1902, plate 8.
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«This fine Pecten was brought from the Chatham Islands by Professor A. Dendy, and was given to me to describe.
Pecten dendyi, sp. nov.
Shell equivalve, compressed, inequilateral, the posterior end produced. Ears rather unequal; the anterior larger, with five ribs, the posterior with two ribs. Byssal notch almost obsolete. Valves plicated, eight ridges on the left and nine on the right valve. Ridges narrower than the sinuses on the left valve, broader than the sinuses on the right valve. The whole surface, both ridges and sinuses, covered with fine radiating ribs, crossed by delicate growth-lines, which are almost obsolete on the right valve. Length, 2·6 in.; height, 2·3 in.; greatest thickness, 0·7 in.
Locality.— In a calcareous sandstone, Chatham Island. This species differs from P. burnetti in being larger, inequilateral, more compressed, and in having more than seven folds. It is probably of Miocene age. The type is in the Canterbury Museum.» FREDERICK WOLLASTON HUTTON, 1902
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«3. Mesopeplum dendyi (Hutton, L902) : an unusually large species (to c. 80 mm high) with 6 or 7 plicae; occurs only in the Momoe-a-Toa Shellbed, Chatham Islands (early Opoitian).»
BEU, A. G. 1995. Pliocene Limestones and their scallops. Lithostratigraphy, pectinid biostratigraphy, and paleogeography of eastern North Island late Neogene limestone. Institute of Geological & Nuclear Sciences Monograph, 10: 1-243, figs. 1-95. (New Zealand Geological Survey Paleontological Bulletin, 68). Institute of Geological and Nuclear Sciences, Ltd., Lower Hutt, New Zealand. [p. 52]
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«PI. 32 b,g. Mesopeplum (Mesopeplum) dendyi (Hutton, 1902) [Pecten dendyi Hutton 1902, p. 196]. Type species of Dendopecten Hertlein, 1936 (= Mesopeplum Iredale, 1929) (Pectinidae).
Large for subgenus (47-72 mm high), obliquely elongated postero-ventrally, umbo at or a little behind anterior third of length; 2 valves equally inflated. The most prominent sculpture is 6 or 7 radial folds, broad and closely spaced on right valve, narrow and widely spaced on left valve, folding whole shell including commissure; superimposed on and between major folds are many prominent radial costae, low, wide, and closely spaced on right valve, narrow, widely spaced, and with very narrow intermediate costellae on left valve. Ears very unequal; posterior ones small, with posterior margin inclined strongly backward, bearing 2 or 3 narrow radial costellae; anterior ears twice as long as posterior, with antero-ventral margin contracted strongly to disc, without ctenolium in adult, bearing 5 or 6 narrow radial costae. Dorsal margin of right valve ears higher than and bending slightly over dorsal margin of left valve ears. Interior not seen - all specimens articulated.
Early Opoitian, Momoe-a-Toa Shellbed, Cape Young, northern Chatham Island (type), the only known locality; abundant, with abundant Sectipecten allani and Chlamys seymouri, and rare Mesopeplum (Borehamia) toaense. The abundant pectinids at Momoe-a-Toa occur in tuff and seem to have lived in an off-shore, hard-ground situation.
The lack of a ctenolium and the equally convex valves show that, like modern specimens of M. convexum (PI. 44g), Mesopeplum dendyi was a free-lying species that swam actively to avoid predators. It is larger, more obliquely elongated, and with slightly more numerous radial folds than other M. (Mesopeplum) species.
Figured specimen (PI. 32b, g): GS1176, CH/f2, Momoe-a-Toa Shellbed, Cape Young, northern Chatham Island, early Opoitian (TM4232, NZGS) x 1.»
BEU, A. G. & P. A. MAXWELL. 1990. Cenozoic Mollusca of New Zealand. New Zealand Geological Survey Paleontological Bulletin, 58: 1-518, pls. 1- 57. [p. 278, 280]
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Mesopeplum (Mesopeplum) dendyi (Hutton); A. G. Beu & P. A. Maxwell, 1990, Cenozoic Mollusca of New Zealand, plate 23, figures b, g.
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