Chlamys (Mimachlamys) taiaroa Powell, 1952
POWELL, A. W. B. 1952. New Zealand Molluscan Systematics, with Description of New Species. Pt. I. Records of the Auckland Institute and Museum, 4 (3): 169-185, pls. 35, 36. [p. 169, pl. 35, fig. 1]
«Chlamys (Mimachlamys) taiaroa n. sp. Pl. 35, fig. 1.
Shell resembling dichroa in size, shape and coloration, but more inftated and with different sculptural detail. In dichroa the radials are strong, broad and flat-topped with channeled interpaces throughout, the concentric lamellae closely spaced, relatively strong but not spinose.
In taiaroa the radials are narrowly rounded and channelled only in the early growth stages. After about 25 mm. the radials spread to broadly triangular with the addition of a weak margining radial on each side and one or two secondary radials in each intercostal space. The concentric lamellae are weak, scarcely apparent in the interspaces but forming weak irregular scales on both primary and secondary radials. "Camponectes" striations present but very weak compared with those in dichroa. The primary radials range between 15-20 in taiaroa and 18-21 in dichroa. Holotype with 19 primary radials on the right valve and 18 on the left. Anterior lug of right valve with six scaly radiate ribs. Colour pink to orange-pink, alternating in intensity in the form of broad concentric zones corresponding with growth stages. Colour stronger and zones more clearly defined on the inside. Height, 43.0 mm. Length 42.0 mm. Thickness (2 valves) 16.0 mm. (holotype)
" 39.5 mm. " 40.0 mm. " " 16.0 mm. (paratype) " 37.5 mm. " 36.0 mm. " " 15.0 mm. " " 41.5 mm. " 38.5 mm. " " 11.0 mm. (dichroa) " 41.0 mm. " 39.0 mm. " " 10.0 mm. " " 31.0 mm. " 31.5 mm. " " 8.75 mm. " Locality: Off eastern coast of Otago, 50-70 fathoms (trawled by Captain J. Black, Dunedin) . Hololype: Auckland Museum, presented by Mr. J. G, Smith, Dunedin. Paratype in collection of Mrs. N. Garder. Auckland. The Chatham Island shells figured by Finlay (1928, Trans. N. Z. Inst. 59, p. 269, PI. 42, figs 45-48) do not represent typical dichroa, which is quite accurately portrayed in Suter's Atlas, PI. 52, fig. 1. Finlay's material is finer and more delicately ribbed, but I have two strongly ribbed typical dichroa fram Kaingaroa, Chatham Islands. There is insufficient material available to determine if there is more than one species of the dichroa group at the Chathams.
A series of ten topotypes of dichroa from the stomachs of cod taken at Port Pegasus, Stewart Island, are constant in their strong flat-topped radials with channelled interspaces and non-inflated valves. Young examples of Chlamys delicatula Hutton, a species that occurs commonly on the continental shelf of Eastern Otago somewhat resemble taiaroa, but are readily distinguishd by their shape, higher than broad, more numerous radials and thicker, stronger shell.» ARTHUR WILLIAM BADEN POWELL, 1952
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A. W. B. Powell, 1952, plate 35.
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