GNS Science

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

New Zealand Cenozoic Mollusca

Gemmula n. sp.


(Pl. 26f): GS9872, N2/f7611, Te Pokere, north shore of Parengarenga Harbour, Northland, Altonian (GNS)

Beu & Maxwell (1990): Chapter 11; p. 236; pl. 26 f.

Classification: Turridae: Turrinae

Description: Rather small for subfamily but large for New Zealand members of the genus (height 25-40 mm), fusiform, spire about half total height. Protoconch corneal, of about 4 whorls, last 2.5 whorls with narrow, distant axial costellae and a narrow cord margining upper suture. Teleoconch of 8-9 whorls, sharply keeled at or somewhat below middle on spire, sutural ramp concave; last whorl with 2 additional angulations, excavated below, with a moderately long neck. Axial sculpture of tubercles on peripheral keel, somewhat rounded on early whorls, but becoming vertically compressed and subtriangular on later whorls, producing a serrate periphery; 13-15 tubercles on each adult whorl. Spiral sculpture on spire whorls of a low, flat-topped cord on periphery, a narrow suprasutural cord that rises above suture on penultimate whorl to form one of the prominent keels on the last whorl, and fine threads between these cords and on ramp. Last whorl with a prominent cord emerging near top of base, similar in strength to the one above, and several much weaker cords, with interstitial threads, on lower part of base and on neck. Stronger basal spirals weakly crenulate. Outer lip with a deep, narrowly V-shaped anal sinus, its apex on peripheral keel, lirate within.

Comparison: This highly distinctive species differs from other New Zealand Gemmula species in its relatively large size, in having a sharply serrate peripheral keel, and in its relatively simple spiral sculpture. It occurs with G. clifdenensis in siltstone of the Paratoetoe Formation at Parengarenga Harbour.

Distribution: Altonian-Clifdenian; Paratoetoe Formation, Paratoetoe and Te Pokere, north shore, Parengarenga Harbour (very common); mouth of Little Wanganui River, west Nelson (uncommon); Calamity Point Sandstone, Clifden (uncommon).

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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