GNS Science

Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)

New Zealand Cenozoic Mollusca

Trachycardium (Ovicardium) rossi Marwick, 1944


(Pl. 34a): GS4252, Q22/f7545, Middle Waipipi Shellbed, Waverley Beach, west of Wanganui, Waipipian (GNS)


(Pl. 34b): GS4252, Q22/f7545, Middle Waipipi Shellbed, Waverley Beach, west of Wanganui, Waipipian (GNS)

Beu & Maxwell (1990): Chapter 14; p. 284; pl. 34 a,b.

Synonymy: Trachycardium (Ovicardium) rossi Marwick 1944, p. 268; Trachycardium (Ovicardium) parki Marwick 1944, p. 269; Acrosterigma (Ovicardium) rossi

Type species of Ovicardium Marwick, 1944

Classification: Cardiidae: Trachycardiinae

Description: Very large for genus (90-102 mm high), inflated-oval to slightly triangular, relatively thin-shelled for its size, with low umbones; inner ventral margin coarsely and deeply crenulate. Sculpture of 40 to 50 high, narrow, flat-topped, almost smooth radial costae of square section, separated by flat-bottomed interspaces each about the same width as, or a little narrower than, 1 costa; costae are weakly noded by low commarginal lamellae near ventral margin and particularly on anterior end, and 10 costae on very poorly demarcated posterior area are of slightly more triangular section than others. Hinge with a long but low, square-ended ligamental nymph in both valves, 1 large and 1 very small cardinal tooth and a median socket in both valves, a weak, shallow, diagonal groove between posterior cardinal tooth and nymph in both valves, a large anterior lateral and 2 very small posterior lateral teeth in left valve, and 1 large and 1 small anterior lateral teeth and 1 small posterior lateral tooth in right valve. Adductor scars large, subcircular, coarsely striate; pallial line without sinus.

Comparison: Trachycardium rossi is very distinctive among world Trachycardium species because of its large size, its relatively short shape, and its prominent, smooth ribs of square section, and no other New Zealand Cardiidae resemble it; the Clifdenian species Acrosterigma delectabilis (Clifden, Southland) is small (49 mm high), fragile and much more finely sculptured.

Distribution: Kapitean-Mangapanian; early Nukumaruan ?. Sandstone in platform to west of and above Te Reinga Falls, Wairoa River, northern Hawke's Bay, Waipipian (type of T. rossi); Butler's Shell Conglomerate, Ototoka Beach, Wanganui, Castlecliffian (type of T. parki , a very abraded remanié specimen); spectacular but uncommon in shallow-water, near-shore, soft-bottom facies in east coast, North Island, particularly Tokomaru Sandstone (Kapitean) of Gisborne district, a few localities of Opoitian and Waipipian age in Hawke's Bay (common at Te Reinga Falls) and Bull Creek Limestone in Bull Creek, Ruakokopatuna Valley, southern Wairarapa (early Nukumaruan); in Wanganui basin, a few specimens are known from the Waipipi Shellbeds and from higher Pliocene shellbeds (Mangapani, Wilkies), but specimens from Nukumaru Limestone (Nukumaruan; recorded by Fleming 1953) and Butler's Shell Conglomerate (basal Castlecliffian; type of T. parki) are all abraded, incomplete specimens eroded from older formations.

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
ISBN 978-0-478-19705-1
ISSN 1177-2441
(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)


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