Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 46d): GS5833, Y14/f7505, Te Piki, near East Cape, Haweran (oxygen isotope stage 7) (GNS)
(Pl. 46f): GS5833, Y14/f7505, Te Piki, near East Cape, Haweran (oxygen isotope stage 7) (GNS)
Beu & Maxwell (1990): Chapter 16; p. 343; pl. 46 d,f.
Synonymy: Arthemis lambata Gould 1850 (in 1846-1850), p. 277; Dosinia (Dosinia) lambata; Dosinia (Asa ?) lambata, Beu & Maxwell 1990, p. 343, pl. 46d, f.
Classification: Veneridae: Dosiniinae
Description: Small for genus (24-33 mm long), well inflated, circular apart from weakly protruding umbones, thin and fragile, with smooth margins. External sculpture of exceedingly fine, closely spaced, commarginal ridges, about 50 per cm, giving freshly preserved shells a silky sheen; ridges are low and wide over most of disc, but raised into thin lamellae over anterior and posterior ends; crossed by a few very narrow, faint, radial grooves. Lunule small, narrow, deeply impressed. Hinge thin and narrow, teeth much as in D. subrosea (below) but much shorter and thinner, and anterior cardinal tooth in each valve curved. Adductor scars narrow, very weakly impressed; pallial sinus very deep, more than half shell length, V-shaped with narrowly rounded apex, directed at top of anterior adductor scar.
Comparison: Dosinia lambata is smaller and has a much thinner shell, very much finer sculpture, and a much narrower hinge than all other New Zealand Neogene to Recent Dosinia species, and its subgeneric position has been uncertain. Beu (2006, p. 271) followed Maxwell's (2009) new subgeneric assignments when he adopted Dosinia (Fallartemis) Iredale, 1930 for D. lambata. The small size, circular shape, very fine, silky-looking commarginal sculpture, and the hinge and pallial line details of D. lambata agree with those of Fallartemis amina Iredale (1930, p. 75, pl. 9, fig. 14, 15) from North Queensland (although the correct name for this species requires considerable research; Iredale mentioned two earlier names for similar shells). The only other named species that is so nearly circular is D. (Phacosoma) maoriana, which differs in its very much thicker shell, wider hinge, and much wider commarginal ridges.
Distribution: Duntroonian-Recent; Recent, New Zealand (type). Common today deeply buried in fine soft sediment (mostly in black anoxic mud) in bays and on the continental shelf, in about 5-50 m; apparently identical fossils are not uncommon in shallow soft-bottom facies as old as Duntroonian (Oligocene) (e.g., Chatton and Wendon Valley, near Gore) although it is difficult to be certain that such fragile shells have identical hinges to Recent ones; uncommon in Nukumaruan and Castlecliffian siltstone in Wanganui, Hawke's Bay, and Wairarapa, and common in the Haweran Te Piki bed near East Cape.
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)