GNS Science

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

New Zealand Cenozoic Mollusca

Pitar (Hyphantosoma) sculpturata (Marshall, 1918)


(Pl. 23h): GS9730, Q8/f9828, Holland's Point, Pakaurangi Point, Kaipara Harbour, Otaian (GNS)

Beu & Maxwell (1990): Chapter 11; p. 219; pl. 23 h.

Synonymy: Macrocallista sculpturata Marshall 1918, p. 272

Classification: Veneridae: Pitarinae

Description: Size moderate for subfamily (length 25-40 mm), ovate, strongly inflated; posterior area poorly defined, slightly concave. Lunule moderately large, bounded by a shallow groove but not impressed; no escutcheon. Sculpture, apart from fine growth lines, of narrow zig-zag grooves, strongest at both ends. Left hinge with a prominent anterior lateral tooth well separated from lunule and from cardinals; a lamellar, almost vertical anterior cardinal; and a thin median cardinal which is subparallel to the lamellar posterior cardinal which in turn is separated by a narrow groove from the thin nymph. Right valve with a deep anterior lateral socket; a thin anterior cardinal tooth with a narrowly triangular median cardinal close behind, and a narrowly triangular, strongly bifid posterior cardinal. Pallial sinus moderately deep, slightly ascending, apex rounded. Margins smooth.

Comparison: Pitar sculpturata is readily distinguished from other New Zealand venerids by the unusual fine zig-zag sculpture. Altonian specimens of Pitar (Hyphantosoma) from Clifden, Southland (Calamity Point Sandstone, Long Beach Shellbed) have been assigned to this species, but they differ from topotypes in having narrower but higher umbones and may not be conspecific. The occurrence of this distinctive subgenus in the New Zealand Miocene is biogeographically interesting, as the only other records are from the Oligocene to Pliocene of the West Indies.

Distribution: Otaian-Altonian; Pakaurangi Formation, Pakaurangi Point, Kaipara Harbour (type); east of the Puketoi Range, southern Hawke's Bay. A poorly preserved right valve from the Tongaporutuan of Gisborne district was doubtfully referred here by Marwick (1931, p. 79).

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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