Cyclochlamys lemchei (Powel, 1958)
POWELL, A. W. B. 1958. Mollusca of the Kermadec Islands Pt. I.. Records of the Auckland Institute and Museum, 5 (1-2): 65-85, pls. 9-11 [p. 70, pl. 9, figs. 7, 8]
1958 Chlamydella favus lemchei Powell, 1958
A. W. P. Powell, 1958, plate 9.
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«5helI small thin suborbicular, right valve larger and slightly more convex than the left. Sculpture discrepant, that of the left valve the stronger, consisting of a maroscopic dense linear spaced cover of divergent meandering weakly squamose rounded threads crossed over the early growth stages by crispIy regularly spaced concentric lamellae which rapidly diminish and become obsole; that of the righ valve, visible only under high magnification, shows a very dense surface network pattern resolving into narrow hexagonal spaces arranged in radial series.
Left valve with the umbo sharp and projecting beyond hinge line, right valve with umbo smaller and not extending beyond hinge line. Auricles unequal the anterior narrow and produced, sculptured with ten crisp radials latticed by lammellae. Colur of leftalve yellowish-brown diffused with light reddish-brown which sometimes resolves into a radiate or even a chevroned pattern. Right valve with a well defined byssal sulcus but not ctenolium. Length, 4.5 mm.; height. 4.5 mm. (Holotype—left valve).
Length, 5.9 mm.: height, 5.5 mm. (Paratype—right valve). Locality: Galathea St. 674, 29° 15' S.; 177° 5' W., off Raoul Island, Kermadecs, 75-85 metres, 3: 3: 1952. The Kermadec shell appears to be very closely allied to the New South Wales favus Hedley, differing only in the rapid obsolescence of the concentric lamellae in the left valve, with compensating stronger development of the radial sculpture.»
ARTHUR WILLIAM BADEN POWELL, 1958
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«Type material
Holotype ZMUC BIV-39; off Raoul Island, Kermadec Islands, 29º15’S, 177º05’W, 75–85 m, 3 Mar. 1952, RRS Galathea (stn 674). Material examined
The holotype (see above), and other material listed by Dijkstra and Marshall (1997: 85). Description
Shell up to 6.22 mm wide, about as wide as high, subcircular, equivalve (relatively narrow, thin ventral margin of right valve disintegrating post mortem: thickened inner part 93–95% height of left valve), left valve more convex than right valve. Left valve with extremely variable, highly irregular colour pattern of yellowish or reddish brown, orange, and opaque white streaks, spots, maculations and chevrons on a translucent ground; right valve translucent white. Some specimens with single internal radial rib at posterior end on one or both valves. Prodissoconch-dissoconch boundary unclear, but probably represented by third commarginal lamella at about 300 μm length; PI smooth, convex; PII crisply sculptured with 3 commarginal growth lamellae and fine, wavy, broken radial threads. Dissoconch left valve dissoconch disc densely covered with numerous, fine, crisp, radial threads that gradually resolve over first 1 mm shell height, multiplying by intercalation, very gradually enlarging and parting, splaying increasingly outwards with increasing shell size in ‘camptonectes’ pattern; early disc up to about 1.20 mm shell length additionally with crisp, widely and rather regularly spaced commarginal riblets that are stronger than intersected radial threads. Anterior auricle distinctly larger than posterior one. Anterior auricle with crisp, widely and rather regularly spaced commarginal lamellae that intersect oblique radial riblets with interspaces about as wide as those of commarginal lamellae, these superimposed on yet finer, more densely crowded radial threads. Posterior auricle with fine, crisp, crowded radial riblets, parallel to dorsal margin dorsally, oblique ventrally, intersected by crisp, broken commarginal lamellae. Right valve disc and ventral half of posterior auricle with outer layer of commarginally elongate, hexagonal prisms that form relatively narrow, flexible ventral apron; dorsal margin serrate. Anterior auricle with rather regularly spaced commarginal lamellae, and up to 8 radial threads that multiply by intercalation, intersections with erect, rounded scales. Posterior auricle with fine, crisp, crowded radial threads covering dorsal half. Distribution
Wallis and Futuna (Dijkstra 2001), and Kermadec Islands, 27–420 m; taken alive at 82–165 m. Shells locally common (Fig. 24). Remarks
Cyclochlamys lemchei is distinctive among known Cyclochlamys species in the combination of relatively large size (width up to 6.22 mm) strong, variable colour pattern, sculpture of numerous fine radial threads in ‘camptonectes’ pattern, the relatively narrow flexible apron at the ventral margin of the right valve, and in that some specimens have a single internal radial rib at the posterior end on one or both valves. Two valves from off Wallis and Futuna islands (Dijkstra 2001: 88, figs 27–28, 36–38) are indistinguishable from Kermadec Islands specimens.» 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. 29, 31]
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Cyclochlamys lemchei (Powell, 1958); H. H. Dijkstra & B. A. Marshall, 2008, The recent Pectinoidea of the New Zealand region, figures 25F-25I
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«Remarks: The present specimens are indistinguisable from the type material. Powell (1958: 71) compared C. lemchei with the southern Australian species Cyclochlamys favus (Hedley, 1902), and observed some differences: "the rapid obsolescence of the concentric lamelIae in the left valve, with a compensating stronger development of the radial sculpture". C. lemchei differs, however, in attaining up to about 6 mm in length instead of about 3 mm, and is more orbicular in shape. Moreover, C. lemchei has a well developed colour pattern, while C. favus is colourless. The sculpture of the left valve of C. favus is highly variable, ranging from almost smooth to concentrically lamellate, radially lirate or reticulate. C. lemchei is constantly ornamented with diverging lirae. The hexagonal microsculpture of the right valve of C. lemchei is finer than in C. favus. Another closely allied species is Cyclochamys mestayerae (Dell, 1956) from off northern New Zealand, which, however lacks the sculpture on the left valve and is colourless.»
DIJKSTRA, H. H. & B. A. MARSHALL. 1997. Pectinoidea (Mollusca: Bivalvia: Propeamussiidae: Pectinidae) of Lord Howe Island, Norfolk Island and the Kermadec Islands. Molluscan Research, 18 (1): 73-114, figs. 1-13. [p. 85]
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Cyclochlamys lemchei (Powell, 1958); H. H. Dijkstra & B. A. Marshall, 1997, Pectinoidea (Mollusca: Bivalvia: Propeamussiidae: Pectinidae) of Lord Howe Island, Norfolk Island and the Kermadec Islands, plate 5.
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