GNS Science

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

New Zealand Cenozoic Mollusca

Zeacuminia planitas Laws, 1940


(Pl. 37z): GS1560, W19/f8480, Waihua River, northern Hawke's Bay, Waipipian (GNS)

Beu & Maxwell (1990): Chapter 14; p. 303; pl. 37 z.

Synonymy: Zeacuminia planitas Laws 1940b, p. 56

Classification: Terebridae

Description: Small for genus (12-30 mm high), very tall and slender, spire 3.5-4 times height of aperture and canal; whorls and whole spire outline flat-sided apart from 2 nodule rows. Sculpture of 2 low, narrow, very weakly denned spiral cords, 1 below suture and 1 at peribasal angle (immediately above suture on spire whorls), raised into prominent, narrowly rounded, rather widely spaced nodules where crossed by axial costae, 11-15 per whorl; costae are low and ill-defined over wide median zone between nodules but swell into prominent nodules at upper and lower suture, fading out rapidly below periphery on last whorl. Last whorl increasing in diameter from suture to peribasal angle to maintain spire angle, then contracting abruptly to short, narrowly waisted neck and short, narrow, strongly twisted, widely open canal; fasciole defined only by its low, narrow bordering ridge. Aperture small, quadrate. Protoconch very small, conical, multispiral, with a narrowly pointed apex.

Comparison: The small size, straight outlines, very short base, and sculpture consisting essentially of only two rows of nodules make Zeacuminia planitas one of the most distinctive species of the genus; it apparently descended from the Early Miocene Z. biplex (Pl. 22u). The other reasonably common Pliocene species, Z. murdochi (Opoitian-Mangapanian, Kaawa Creek, Wanganui and Hawke's Bay) is much larger, short and wide for the genus, with a long base and canal, evenly convex whorls, and sculpture of low axial costae only.

Distribution: Opoitian-early Nukumaruan; Waihi Beach, Hawera, Waipipian (type), uncommon; uncommon in Waipipian and Mangapanian shellbeds of shallow-water facies along the Wanganui-South Taranaki coast; moderately common at a few localities in Wairoa district, northern Hawke's Bay (Opoitian-Mangapanian; notably in Waihua River) and in the Mangahao district, west of Pahiatua, northern Wairarapa (Mangapanian-early Nukumaruan).

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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