Hyalopecten mireilleae Dijkstra, 1995
DIJKSTRA, H. H. 1995. Bathyal Pectinoidea (Bivalvia:
Propeamussiidae, Entoliidae, Pectinidae) from New Caledonia and adjacent areas. In: Bouchet, P. (Ed.), Résultats des Campagnes MUSORSTOM,
Volume 14. Mémoires du Muséum national d'Histoire naturelle, 167: 9-73, figs. 1-154. [p. 48, figs. 79-82]
1995 Hyalopecten mireilleae Dijkstra, 1995
H. H. Dijkstra, 1995, figures 79-86.
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«TYPE MATERIAL. — Holotype MNHN. Paratypes: 2 MNHN, 2 HD.
TYPE LOCALITY. — S New Hebrides Arc, VOLSMAR, stn DW 55, 20°59' S, 170°02' E, 710 m. MATERIAL EXAMINED. — New Caledonia. BIOCAL: stn CP 72, 22°09' S, 167°33' E, 2100-2110 m, 1 juv. rv (paratype). — stn KG 85, 20°59' S, 167°00' E, 1639 m, 1 lv (paratype). Loyalty Islands. MUSORSTOM 6: stn CP 438, 20°23' S, 166°20' E, 780 m, 1 lv (paratype HD). — Stn DW 489, 20°48' S, 167°06' E, 700 m, 1 rv (paratype HD). New Hebrides Arc. GEMINI: stn DW 55, 20°59' S, 170°02' E, 710 m, 1 spm (holotype). DISTRIBUTION. — Eastern New Caledonia to the New Hebrides Arc, 700-2110 m, living in 710 m. DESCRIPTION. — Shell small, up to ca. 14 mm high, fragile, oblique, elongate, inequivalve, inequilateral, semi-transparent white, right valve more convex than left, auricles unequal, umbonal angle ca. 90°.
Prodissoconch ca. 200 μm in height. Left valve externally sculptured over entire surlace with regular spaced concentric lamellae that enlarge towards ventral margin. Lamellae near periphery more strongly curved and more irregularly and closely spaced. Delicate radial lirae between concentric lamellae, more prominent directly beneath each concentric lira. Anterior and posterior auricles with curved, closely spaced concentric lirae, somewhat more prominent and widely arranged on anterior. Anterior auricle larger than posterior auricle, sculpture similar to that of disc margins. External sculpture visible from interior. Interior surface nacreous. Right valve with regular concentric lamellae and many delicate interstitial radial lirae similar to those on left valve. Anterior auricle separated from disc by distinct suture, sculptured with irregularly spaced, concentric lamellae, developed into spinous scales on dorsal margin. Posterior auricle with close-set concentric lamellae and continuous with the disc margin. Resilifer triangular. No cardinal crura exposed. Only an inactive ctenolium is developed (two teeth of active ctenolium are developed in paratype from BIOCAL: stn CP 72). Byssal notch present. Dimensions of the holotype: H 13.4, L 11, D 5.6 mm. REMARKS. — A somewhat similar species is Hyalopecten tydemani Dijkstra, 1990 from the Ceram Sea (Indonesia), which is smaller, less oblique, and ornamented with very closely spaced concentric lamellae. Moreover, the delicate interstitial radial lirae are absent. The western Atlantic species H. strigillatus (Dall, 1889) is more like H. tydemani, but is somewhat more strongly sculptured with closely spaced concentric lamellae. The anterior auricle of the right valve in both species is relative smaller in H. mireilleae. Hyalopecten pudicus (E.A. Smith, 1885) from the southern Indian Ocean is more depressed, slighly more orbicular, with an undulating surface. H. pudicus is more similar to H. dilectus from the Atlantic Ocean. Hyalopecten neoceanicus (Dall, 1908) from the Galapagos Islands is more orbicular and depressed with a slightly undulating surface, and reticulate sculpture. Hyalopecten profundicola (Okutani, 1962) from abyssal depths of Japan is more depressed, more oblique and orbicular, and the right valve has more closely spaced lamellae. Hyalopecten hadalis (Knudsen, 1970) from the Kermadec Trench is somewhat larger (up to 20 mm in height), oblong, strongly undulated, and sculptured with fine, close-set radial striae, anterior auricle of the right valve very small and byssal notch well developed. Hyalopecten sp. (KNUDSEN, 1970: 102) from the Tasman Sea is much larger (up to ca. 35 mm), also oblong and strongly undulated, and sculptured with radial riblets. ETYMOLOGY. — Named after Mrs Mireille Moreau, technician at MNHN, who has skilfully been processing the bivalves from the various expeditions around New Caledonia.» HENK H. DIJKSTRA, 1995
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