Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 43g): R22/f6353, Tainui Shellbed, Castlecliff, Wanganui, Castlecliffian (Auckland University Geology Department)
Beu & Maxwell (1990): Chapter 16; p. 333; pl. 43 g.
Synonymy: Chiton zelandicus Quoy and Gaimard 1835, p. 400; Acanthochoetes hookeri Gray 1843, p. 262; Acanthochiton zealandicus doubtlessensis Ashby 1926, p. 12; Acanthochiton brookesi Ashby 1926, p. 14; Acanthochiton zelandicus amplificatus Iredale and Hull 1930, p. 166; Chitonellus zelandicus; Acanthochites zelandicus
Description: Small (median plates rarely more than 5 mm wide and 4 mm long), thin. Very similar in most characters to valves of Notoplax mariae (Pl. 44a, d, h), and many fossils are difficult to identify with certainty, even to genus; finely sculptured, markedly triangular, relatively wide median valves associated with anterior valves with 5 prominent radial ribs can be identified as N. mariae with some confidence; whereas markedly smaller, slightly more rounded and more antero-posteriorly elongate median valves with coarser tegmental granules, wider jugal areas, and more prominent radial ridges between lateral and pleural areas, associated with a relatively long anterior valve lacking radial ridges, are identified as A. zelandica (at least, in Castlecliffian and younger rocks). Such specimens are, however, among the least common of fossil chiton plates, presumably reflecting the intertidal rocky shore habitat of living A. zelandica and the scarcity of preservation of this environment in the fossil record.
Comparison: See description.
Distribution: Castlecliffian-Recent; Recent, New Zealand (types of all names listed in the synonymy). The only fossil specimens certainly referred here are a few from Tainui Shellbed at Castlecliff, Wanganui (Castlecliffian) in Auckland University Geology Department, and a few from Ohope Beach, Whakatane (Castlecliffian) in the NMNZ.
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
(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)