Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
| | Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990) |
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  (Pl. 43b): Ohope Beach, Whakatane, Castlecliffian (National Museum of N.Z.), anterior valve |
  (Pl. 43d): coast west of Waipipi Point, Waverley Beach, west of Wanganui, Waipipian (GNS, ex F. D. Chambers colln.), median valve |
Beu & Maxwell (1990): Chapter 16; p. 332; pl. 43 b,d.
Synonymy: Lorica volvox of Suter 1907c, p . 297 (not of Reeve, 1847); Lorica haurakiensis Mestayer 1921, p. 177; Aulocochiton haurakiensis
Type species of Zelorica Finlay, 1926 (= Lorica H. and A. Adams, 1852)
Classification: Schizochitonidae
Description: Very large for fossil chiton plates (median valves up to 20 mm wide, 10 mm high, 8 mm long; valve 2 up to 11 mm long); short and very wide, highly arched, with sharply angled dorsum; sutural laminae wide and very short, insertion plates thick, very short, weakly pectinate. Colour pattern of alternate broad bands of reddish brown and white remains on many fossils. Anterior valve (rare as a fossil) short and widely arcuate, very steeply arched, with concave anterior silhouette and embayed posterior edge, bearing about 10 very prominent, narrowly crested radial costae, each with a row of nodules down its crest. Median valves (common) very wide and short, with many high, narrow, almost smooth longitudinal costae on pleural areas and dorsum and 2 or 3 narrow-crested, widely spaced, nodulous costae on lateral areas; without jugum; valve 2 narrowly triangular, markedly longer at dorsum than valves 3-7. Posterior valve (not seen fossil) very small, essentially like median valves, with posterior mucro, longitudinally costate pleural areas and dorsum, and 1 coarsely nodulous costa along each side of posterior margin.
Comparison: Lorica haurakiensis is easily recognised by its large size, the obviously angled sides and median ridge, its prominent costae, the prickly nodules on the costal crests, the strongly concave anterior slope of the anterior valve, the long, triangular second valve, and the small posterior valve with a terminal mucro.
Distribution: Waipipian-Recent; Recent, Hauraki Gulf, east of Auckland (type). Although uncommon in the living fauna (specimens are known from hard substrates throughout New Zealand, from the intertidal zone down to about 50 m) this is one of the largest and more common of fossil chitons; specimens have been examined from the Waipipi shellbeds, Waverley Beach (Waipipian), Waihi Beach, Hawera (Waipipian), Hawke's Bay Nukumaruan siltstone (several localities), Ohope Beach, Whakatane (Castlecliffian), and are common in the shellbed on Hauriri Terrace (oxygen isotope stage 5a, 80 000 years BP) at Waverley Beach (12 valves).
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)