Cyclochlamys transenna (Suter, 1913)
SUTER, H. 1913. Manual of the New Zealand Mollusca. With an atlas of quarto plates. Published by the Authority of the Government of New Zealand. Wellington. 1120 p. Atlas of plates (1915), 72 pI. [p. 881, pl. 52, fig. 3]
1913 Pecten transenna Suter, 1913
H. Suter, 1913, plate 52.
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«Left valve minute, somewhat oblique, roundly ovate, with straight dorsum and subequal ears, translucent, white, very thin and fragile, moderately convex, with numerous radial riblets and concentric threads. Beak slightly anterior, a little raised, rounded, and smooth. Ears subequal, small, not distinctly marked off from the disc. Anterior end a little shorter, convex, receding below, slightly sinuated below the ear; posterior end straight above and rapidly descending, produced and convex below; the ventral margin broadly convex. Sculpture consisting of numerous fine radiate riblets, with a few secondary shorter riblets, crossed by subequidistant fine concentric lines, the points of intersection with small tubercles. Colour white. Interior white, shining, smooth. Hinge-line straight, with a small triangular resilium beneath the umbo.
Diameter — Ant. -post., 3.4 mm.; dorso-ventral, 3 mm. thickness, 1 mm. Right valve not seen. Type in my collection. Hab. — Near the Snares, in 50 fathoms (type) ; near the Bounty Islands, in 50 fathoms (Captain Bollons).» HENRY SUTER, 1913
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«Type material
Holotype (lv) NZGS TM.215, 8 paratypes NMNZ M.10949; near Snares Islands, New Zealand, 91 m. Material examined
The type material (see above). Fossil. Ohope (W15/ 644519). Shellbeds below old reservoir in stream at foot of Ohope–Whakatane road, 1970–71, Late Pleistocene (Castlecliffian). Recent. Off E side of Ruamahua-nui Island, Aldermen Islands, 36°57.2’S, 176°05.8’E, 38 m (1 pr, M.112761). Ranfurly Bank, East Cape: 37°36.7’S, 178°51.6’E, alive, 56–63 m (1 pr, M.107588); 37°32.8’S, 178°48.7’E, alive, 94 m (1 pr, M.60710). Lyall Bay, Wellington (many v, M.1416). Black Reef, The Steeples, off Westport, 41º43.48'S, 171º28.19'E, 1–3 m (1 v, M.152414). Chatham Islands: Kaingaroa, beach (1 v, M.12500); Ocean Bay, 43º50'S, 176º47'W, 12–15 m (1 v, M.155380). Abbey Rocks, NE of Haast, 43º41.15'S, 169º20.02'E, 7–11 m (1 v, M.152325). Akaroa Harbour entrance, 43°54’S, 172°57’E, 27 m (1 v, M.54179). NE end of Taumaka Island, Open Bay Islands, off Haast, 43°51.5’S, 168°52.5’E, 6 m (1 v, M.130389). Inner NE side of Jackson Head, 43º57.63'S 168º37.47'E, 8–12 m (2 v, M.155379). Off Seal Rocks, W of Jackson Bay, 43º59.56'S 168º31.45'E, 14–17 m (2 v, M.151829). Milford Sound: 44º34.0'S, 167º45.0'E, 81 m (7 v, M.10361); St Anne Bay, 44º34.5'S, 167º47.0'E, 10–14 m (4 v, M.142844). Bligh Sound: 44º48'S, 167º32'E, 46 m (7 v, M.10197); off Turn Round Point, 44°48.0’S, 167°32.5’E, 31 m (20 v, M.141565). Outer George Sound, 44°52’S, 167°22’E, 32 m (2 v, M.139314). Two Thumb Bay, 44°57.3’S, 167°11.0’E, 15 m (2 v, M.139268). Caswell Sound mouth, 45°00.0’S, 167°08.3’E, 37 m (3 v, M.140189). Deep bay S side of Charles Sound entrance, 45°03.5’S, 167°05.0’E, 26 m (many v, M.139878). Inside Entrance Island, Nancy Sound, 45°06.2’S, 167°01.2’E, 12 m (1 v, M.140638). Doubtful Sound: off Shelter Island No. 2, 45°17.0’S, 166°53.0’E, 27 m (30 v, M.143032); bay N side of W end of Bauza Island, 45º17.0'S, 166º54.5'E, 20 m (1 pr, 30 v, M.141749); Gaol Passage, 45°17.5’S, 166°54.0’E, 46 m (1 v, M.13756). Bradshaw Basin floor, Bradshaw Sound, 45º17.3'S, 167º02.6'E, 415 m (2 v, M.138403). Off Seventy Fathoms Point, Daggs Sound, 45º25.0'S, 166º52.5'E, 20 m (1 v, M.139985). Between unnamed island and Breaksea, Breaksea Sound entrance, 45°35.2’S, 166°39.0’E, 37 m (5 v, M.13834). Wet Jacket Arm, S side of entrance, 45°40.2’S, 166°44.8’E, 42 m (1 v, M.141905). Off “30 fathom” point, inside Five Fingers Peninsula, 45°43.2’S, 166°29.5’E, 37 m (1 pr, 1 v, M.135870). “104 fathom point”, Bowen Channel, Dusky Sound, Chalky Inlet, 45°43.0’S, 166°45.0’E, 10–17 m (7 v, M.143636). Foveaux Strait: off Breaksea Island, alive, 55–64 m (6 pr, M.19843); off Fife Rock, near Ruapuke Island, 7–9 m (3 v, M.19839); fishing grounds, 37 m (2 v, M.19840). Stewart Island: off Faro Island, alive, 55 m (many pr, M.19244); Codfish Island (1 v, M.19842); Chew Tobacco Bay, alive, 18 m (12 pr, M.16875); Smoky fishing grounds, near The Saddle, alive (6 pr, M.9822). Stewart Island: Halfmoon Bay, alive, 27 m (1 pr, M.64644); Bathing Beach (1 v, M.19841; 2 v, M.10321); Mason Bay (1 v, M.4974); Port Adventure, 46–64 m (1 pr, M.19838); Port Adventure, 95 m (1 v, M.42471); off Poutama Island, Big South Cape Island, 55 m (45 v, M.19837). Snares Islands: off “The Breaks”, 48°00.9’S, 166°36.75’E, 33–37 m (many v, M.107578); off Western Chain, 48°03’S, 166°30’E, alive, 70–110 m (5 pr, 3 v, M.135682). E side of Perpendicular head, Antipodes Islands, 19 m (3 v, M.155378). Off Bounty Islands: 73 m (1 v, M.8546); Proclamation Island, 47º42'S, 179º05'E, 39 m (1 v, M.119748). Auckland Islands: Deas Head, 50º31.52'S, 166º13.52'E, 13–18 m (9 v, M.155382); Ocean Island, 50º51.43'S, 166º15.43'E, 13–19 m (9 v, M.155381). Description
Shell up to 3.50 mm high (rarely larger than 2.50 mm), adults higher than wide, vice versa, or about as high as wide, equivalve (broad, thin ventral margin of right valve disintegrating post mortem: thickened inner part 78–83% height of left valve), markedly posteriorly oblique, left valve more convex than right valve, auricles rather smoothly confluent with disc, colourless and translucent. Prodissoconch 400–430 μm long, boundary ill-defined though apparently a growth line shortly after second or third commarginal ridge on PII; PI D-shaped (i.e. valve margins), c. 120 μm long, essentially smooth, tip weakly convex, bounded by prominent, rounded ridge; PII convex, sculpture merging smoothly with that of adjacent dissoconch, comprising fine, crisp radial threads, locally finely nodular at intersections with weak commarginal ridges, outer part with addition of 2 or 3 crisp commarginal ridges. Left valve disc and auricle sculpture commencing immediately, crisp throughout; comprising rounded commarginal lamellae and radial threads of similar thickness, radials multiplying by intercalation, interspaces of similar width, intersections on disc with prominent, rounded, thin-walled, fingernail-like scales that strongly overhang their bases (deceptively resembling solid nodules in plan view). Rate of intercalation of radial riblets extremely variable, typically 8–22 on disc (range generally smaller within populations), scales typically larger on specimens with fewer (more widely spaced) riblets; occasional specimens (but commonly at Auckland, Antipodes and Bounty islands) eventually with up to 50 or more riblets on disc, and with few or no scales. Auricles of similar size, anterior auricle more nearly equiangular than posterior one. Right valve disc and posterior auricle with outer layer of commarginally elongate, hexagonal prisms that form broad, flexible ventral apron. Posterior auricle typically with 1 weak radial thread close beside dorsal margin. Anterior auricle with 4 or 5 radial rows of rounded nodules. Byssal notch of moderate depth, byssal fasciole rather broad. Distribution
Late Pleistocene and Recent. Aldermen Islands, East Cape and Wellington, and South, Stewart, Snares, Bounty, Auckland and Chatham islands, New Zealand, 0–110 m; taken alive at 18–110 m (Fig. 30). Remarks
Typical specimens of Cyclopecten transenna are distinctive in the large size of the overhanging scales, where the radial riblets intersect the commarginal lamellae. Rare specimens (3) from off the Aldermen Islands and East Cape fall within the range of variation in southern populations in shell morphology, and are thus evidently conspecific. Sparse northern populations may be relict pockets dating from the last glacial maximum, when the species may have ranged further north than at present.» 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. 36, 37]
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Cyclochlamys transenna (Suter, 1913); H. H. Dijkstra & B. A. Marshall, 2008, The recent Pectinoidea of the New Zealand region, figures 29A–29E, 29G–29I.
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«Although several workers have commented upon the characters of the right valve in this species, it has never been figured. Left valves occur commonly only in shell sand at Lyall Bay and a single right valve has been found in association with them. This is figured (Fig. 38) for comparison with the other species discussed below. It is considerably flatter than the left valve. Anterior ear with deep byssal sinus, sculptured with two indistinct radials. Posterior ear only slightly differentiated from the disc. Surface of valve with close, microscopic, concentric lines crossed by fine, rather irregular radials. The strength of sculpture varies rather considerably in the left valve. Suter's original specimen was rather worn and two fresh valves from Lyall Bay are figured (Figs. 32, 33) to show the range of variation.
Localities: Off the Snares, in 50 fathoms (type); Mason's Bay, Stewart Island, in shell sand; Lyall Bay, Cook Strait, in shell sand.» DELL, R. K. 1956. The archibenthal Mollusca of New Zealand. Dominion Museum Bulletin, 18: 1-235, pls. 1-25, text-figs. 1-6. [p. 22]
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Cyclopecten transenna (Suter, 1913); R. K. Dell, 1956, The archibenthal Mollusca of New Zealand, plate 4, figures 32, 33, 38.
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