Janupecten subteres Marwick, 1943
MARWICK, J. 1943. Some Tertiary Mollusca from North Otago. Transactions of the Royal Society of New Zealand, 73: 181-192, pls. 25-27. [p. 181, pl. 25, figs. 3, 7]
1943 Janupecten subteres Marwick, 1943
J. Marwick, 1943, plate 25.
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«Shell large, subcircular, thin, flat. Sculpture between that of Janupecten and Lentipecten. Right valve with very faint, flat radial ribs on ears and on posterior and anterior flanks, dorsal and distal margins of ears strongly serrate. Left valve smooth. Surface of both valves, when well preserved with minute, regular, concentric ridges, about 7 per mm.
Height, 93 mm.; length, 92 mm.; inflation (1 valve), 10 mm. Localities: G.S. 2118, Greensand, Green Valley, Waihemo Surv. Dist. (type); G.S. 1314, G.S. 1821, Greensand, Wharekuri; G.S. 2108, Greensand, Te Raumaku School, Otorohanga district. Age: Duntroonian (Upper Oligocene). This shell is so like a Lentipecten that it is questionabl~ whether it is really a Janupecten. The Lentipecten stock, however, extends without sculpture from the Bortonian up to the Urenuian. If subteres is an offshoot of this line, the resemblance of its sculpture to that of Janupecten (and Serripecten) becomes rather a remarkable coincidence. It seems better regarded as a further development of the Janupecten uttleyi-polemicus line that has lost almost all its radials. Convergence of two lineages through obsolescence of sculpture is more likely than through the development of a peculiar sculpture. The smooth left valve is very like that of L. hochstetteri (Zitt.), but the anterior and posterior margins of the ears are straighter.» JOHN MARWICK, 1943
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