Cyclochlamys mestayerae (Dell, 1956)
DELL, R. K. 1956. The archibenthal Mollusca of New Zealand. Dominion Museum Bulletin, 18: 1-235, pls. 1-25, text-figs. 1-6. [p. 24, pl. 4, figs. 36, 39]
1956 Cyclopecten mestayerae Dell, 1956
R. K. Dell, 1956, plate 4.
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«A number of valves from off North Cape, In 75 fathoms, differ from all other described New Zealand species in the characters of the left valves. These are thin, transparent (apart from a deposition of white callus over the upper third) and shining, the only sculpture consisting of sparse, irregular, microscopic radial scratches. The ears are subequally developed, well marked off from the disc, the valve being almost equilateral. Right valve very similar in texture, sculptured with more regular concentrics crossed by very fine, close but irregularly developed radials which are most obvious on the growth lines. Posterior ear sculptured with very fine growth lines, anterior ear indented by a strong byssal sinus, upper portion of ear with three radials.
Length, 2.6 mm.; height, 2.4 mm.; inflation, 0.45 mm. Holotype (M. 9240) a left valve, and paratypes in Dominion Museum. Locality: Six and a half miles east, 5 miles north of North Cape, in 75 fathoms. To add to our knowledge of this puzzling group it should be recorded that from Galathea Station 639, 37° 31' S, 177° 08' E, in 213 metres came three shells belonging to the group. A broken right and a left valve are of the aupouria-powelli type but the third shell (an articulated pair of valves) possesses a nurnber of unusual characters. Firstly, although the specimen is small, the sculpture on each valve appears similar. This consists of microscopically fine, raised radial lines with even finer interstitial concentrics. Secondly, the right valve is only two-thirds the size of the left. The general appearance of the shell is indicated in Fig. 37. This particular fornl cannot be described until better adult material is obtained. In fact the systenlatics of the group in Australasia cannot be understood until a series of articulated valves is obtained.» RICHARD KENNETH DELL, 1956
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«Description
Shell up to 2.90 mm wide, subcircular, equivalve (broad, thin ventral margin of right valve disintegrating post mortem: thickened inner part 77–81% height of left valve), left valve more convex than right valve, umbonal area opaque white and commonly with irregular opaque white radial streaks, elsewhere colourless and perfectly transparent. Prodissoconch globular, smooth apart from growth lines and a few minute punctae; tip an area c. 150 μm long bounded on left valve by thickened rim, and right valve by growth line; prodissoconch-dissoconch boundary indistinct, though possibly represented by commarginal growth line at c. 300 μm length. Dissoconch left valve glossy throughout, smooth apart from fine commarginal growth lines and obscure radial lines. Auricles of similar size. Right valve disc and ventral half of posterior auricle with outer layer of commarginally elongate, hexagonal prisms that form broad, flexible ventral apron. Anterior auricle with fine, close commarginal growth lines, some specimens with 2–4 weak radial rows of scales. Byssal notch of moderate depth, byssal fasciole rather broad. Distribution
Three Kings Islands, N North Island, and NE South Island, New Zealand, 73–447 m; taken alive at 91–252 m (Fig. 27). Remarks
Although originally referred to Cyclopecten, Cc. mestayerae has the right valve microstructure characteristic of Cyclochlamys, so we transfer it to this genus. Cyclochlamys mestayerae is distinctive among Cyclochlamys species from the New Zealand region in that the dissoconch left valve is smooth. A specimen from off the Three Kings Islands (M.34217) had a brood of 11 young, of which seven were about 170 μm wide, and four about 270 μm wide. Two specimens taken alive in the Bounty Trough (NIWA S153) appear to be identical to northern specimens in shell morphology, but one is considerably larger (length 4.00 mm versus 2.90 mm), and they were living at considerably greater depth (1386 m versus 91–252 m), suggesting the possibility that they may represent a similar but distinct allopatric species.» DIJKSTRA, H. H. & B. A. MARSHALL. 2008. The recent Pectinoidea of the New Zealand region (Mollusca: Bivalvia: Propeamusiidae,Pectinidae and Spondylidae). Molluscan Research, 28 (1): 1-88, figs. 1-70. [p. 32]
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Cyclopecten [sic] mestayerae (Dell, 1956); H. H. Dijkstra & B. A. Marshall, 2008, The recent Pectinoidea of the New Zealand region, figures 26A, 26B, 26D, 26E.
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