Cyclochlamys bacata Dijkstra & Marshall, 2008
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. 25, figs. 22B, 22F, 22G]
2008 Cyclochlamys bacata Dijkstra & Marshall, 2008
H. H. Dijkstra & B. A. Marshall, 2008, figure 22.
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«Type material
Holotype (lv) NMNZ M.107576; Wanganella Bank, West Norfolk Ridge, summit, 32°32.6’S, 167°29.2’E, 133 m, 29 Jan. 1981, RV Tangaroa. Paratypes: Wanganella Bank: summit, 32°34.4’S, 167°31.0’E, 113 m (l v, M.107599); E slope, 32°35.3’S, 167°41.8’E, 437–422 m (1 v, M.234142). Material examined
The type material (see above). Description
Shell up to 1.90 mm high, slightly posteriorly oblique, translucent white. Hinge line straight. Prodissoconch apparently 280–290 μm long, boundary poorly defined, but presumably the first sharply defined growth line; PI D-shaped (i.e. valve margins), c. 200 μm long, strongly projecting and narrowly tapered dorsally, flank surmounted by low, rounded, posteriorly-inclined ridge extending from hinge area to ventral margin, sides concave, elsewhere with scattered granules and few, weak radial threads; PII sculptured with very fine, crisp radial threads. Left valve disc and auricles sculptured with radial rows of prominent, radially elongate, ovate nodules that enlarge towards ventral margin, stronger on disc than on auricles, rows multiplying by intercalation, nodules coinciding with intersections of ill-defined radial and commarginal swellings (wear and breakage reveals nodules to be hollow). Right valve unknown. Distribution
Wanganella Bank, West Norfolk Ridge, 113–437 m (shells only) (Fig. 21). Remarks
Cyclochlamys bacata is distinctive among propeamussiids in the combination of very prominent PI with oblique summit ridge, and dissoconch sculpture of rows of prominent, radially elongate nodules. In the absence of the diagnostic right valve, Cyclochlamys bacata is referred to Cyclochlamys rather than Cyclopecten because of the close similarity of its prodissoconch to that of Cc. pileolus n. sp. (see below), the right valve sculpture of which is characteristic of the genus.» HENK H. DIJKSTRA & BRUCE A. MARSHALL, 2008
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