GNS Science

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

New Zealand Cenozoic Mollusca

Zethalia zelandica (Hombron & Jacquinot, 1854)


(Pl. 47l): GS4186, R22/f6469, Shakespeare Cliff Sand, Castlecliff, Wanganui, Castlecliffian (GNS)


(Pl. 47p): GS4186, R22/f6469, Shakespeare Cliff Sand, Castlecliff, Wanganui, Castlecliffian (GNS)

Beu & Maxwell (1990): Chapter 16; p. 347; pl. 47 l,p.

Synonymy: Globulus anguliferus Philippi, 1853 [in 1842-1855], p. 51 (not of J. de C. Sowerby, 1840); Rotella zelandica Hombron & Jacquinot 1854, p. 53; Umbonium zelandicum A. Adams 1855b, p. 189; Ethaliopsis zelandica of Cossmann 1918, p. 223; Umbonium anguliferum; Umbonium (Zethalia) zelandicum

Type species of Ethaliopsis Cossmann, 1918 (not of Schepmann, 1908), and of Zethalia Finlay, 1926

Classification: Trochidae: Umboniinae

Description: Large for genus (15 to 23 mm in diameter), with very low, conic spire, narrowly biangled periphery, wide almost flat base, smooth dorsal surface, and completely filled, almost smooth umbilical plug. Subsutural nodules and circumumbilical sculpture described above under Z. russelli (Opoitian; Pl. 36e, h) and (under same heading) Z. coronata (Waipipian-Mangapanian; early Nukumaruan ?) almost completely lost, the only remnant being weak radial grooves on and shallow margining groove around umbilical plug. Base bearing many very fine spiral grooves; the only other sculpture is 2 narrow, smooth, peripheral spiral cords and weak growth ridges. Modern specimens have a bright colour pattern of red to purple radial streaks, running forward to cross growth lines at a low angle over outer 0.6 of each whorl (except the last, where streaks tend to become narrow, closely spaced, and strictly radial), on a cream or pale pink ground; base pink or cream, with wide purple spiral band outside outer edge of umbilical plug. Colour pattern remains on most fossils, particularly Castlecliffian and Haweran specimens.

Comparison: As described above under Zethalia russelli (Opoitian; Pl. 36e, h), the immediately ancestral Z. coronata is slightly smaller than Z. zelandica, has a slightly less filling umbilical plug, and has more sculpture, with a spiral row of low, rounded nodules below the suture. Z. coronata is common in Waipipian and Mangapanian near-shore sandstone, but its upper limit is uncertain as some weakly nodulous specimens persist in early Nukumaruan populations.

The species name has most frequently been attributed to A. Adams (following Finlay 1926c) but according to Sclater (1893) Adams's paper was not published until 16 May 1855, and so the name was introduced earlier by Hombron & Jacquinot (1854, p. 53).

Distribution: Nukumaruan-Recent; Recent, New Zealand (types of names listed in synonymy). A very abundant fossil in late Nukumaruan, Castlecliffian and Haweran sandstone deposited near shore, just off sandy ocean beaches (it lives now in huge numbers in about three to five metres, in the wave zone off slightly protected sand beaches) and a very useful and precise indicator, along with the clypeasteroid echinoid Fellaster zelandiae Gray, of this near-shore, sandy beach environment.

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)


Back to index page