Laevichlamys Waller, 1993
WALLER, T. R. 1993. The evolution of Chlamys (Mollusca: Bivalvia: Pectinidae) in the tropical western Atlantic and eastern Pacific. American Malacological Bulletin, 10 (2): 195-249, figs. 1-14. [p. 204]
«Laevichlamys, new genus
Etymology.— The name Laevichlamys is derived from the Latin word levis (or laevis), meaning smooth, with reference to macrosculpture of low relief, and the genus name Chlamys.
Diagnosis.— Non-cemented Chlamydini with shagreen microsculpture secondarily absent at least on central sector of disk and commonly on entire shell; radial ribs initially low, tending to originate in ontogeny well after end of prismatic stage, and preceded by zone of uninterrupted antimarginal striae; rib introduction mainly by repeated intercalation medially in interspaces of preceding ribs on both valves, nearly or entirely filling interspaces between ribs; regular cornmarginal lirae absent.
Type species.— Pecten multisquamatus Dunker, 1864, living, tropical western Atlantic.
Other species.— In addition to the type species, extant species included in the new genus are as follows: Pecten irregularis G. B. Sowerby II, 1842; P lemniscatus Reeve, 1853; P. limatulus Reeve, 1853; P. mollitus Reeve, 1853; P. ruschenbergeri Tryon, 1869; Ostrea squamosa Gmelin, 1791; and Chlarnys wilhelminae Bavay, 1904. All of these live in the Indo-Pacific region.
There is still much to learn about the fossil record of this genus, but two extinct species are included thus far: Pecten (Chlamys) lauensis Ladd in Ladd and Hoffmeister, 1945, Fiji, late Miocene or Pliocene; P. shirahamaensis Nomura and Niino, 1932, Japan, Early Pliocene (Masuda, 1962, p. 185). Geographic range.— Western Indo-Pacific and western Atlantic
Stratigraphic range.— Upper Miocene to present.
Discussion.— As argued in the preceding section dealing with the tribe Chlamydini, the new genus Laevichlamys probably has a tropical Indo-Pacific origin, and morphologically advanced species entered the eastern Atlantic in the late Miocene probably via a southern African route of dispersal. The former presence of the genus in the Mediterranean and eastern Atlantic is indicated by the presence in these areas of Hinnites, which likely evolved from a species of Laevichlamys.
Laevichlamys is paraphyletic in that specialized, derived genera such as Hinnites DeFrance, 1821, and Pedum Lamarck, 1799, are excluded (see preceding discussion of the tribe Chlamydini). The alternative to achieve a holophyletic status would be to broaden the concept of the genus to include all of these, but the name based on priority would then become Pedum, a taxon well-known for its highly unusual form and specialized living hibit embedded in massive corals. This would clearly raise havoc with the morphological concepts that have long been attached to particular names.» THOMAS RICHARD WALLER, 1993
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Laevichlamys multisquamata (Dunker, 1864); T. R. Waller, 1993, The evolution of Chlamys (Mollusca: Bivalvia: Pectinidae) in the tropical western Atlantic and eastern Pacific, figures 4a-4i, 4l, 4m.
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H. H. Dijkstra & A. G. Beu, 2018, Living scallops of Australia and adjacent water; Laevichlamys andamanica (Preston), figure 67B; Laevichlamys cuneata (Reeve), figures 67D, 67F; Laevichlamys limatula (Reeve), figures 67E, 67K, 67L; Laevichlamys deliciosa (Iredale), figures 67G-67J.
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«Laevichlamys Waller, 1993
Laevichlamys Waller, 1993: 204. Type species (by original designation): Pecten multisquamatus Dunker, 1864. Recent, tropical western Atlantic.
Diagnosis. Non-cemented or embedded Pedini with weak radial costae or riblets (evenly or unevenly spaced), shagreen microsculpture secondarily absent from most specimens, intercalated antimarginal striae, commarginal ridges absent, byssal notch shallow to deep, ctenolium well-developed, hinge teeth weak.
Distribution. Upper Miocene–Recent (Waller, 1993: 204). Western Atlantic and Indo-West Pacific, living in the subtidal to sublittoral zones.
Discussion. Waller (1993: 204) created a new genus for the chlamydoid taxa with weak to almost smooth macrosculpture. Most of the representative extant species live in the Indo-West Pacific, the exception being the type species (see above).»
DIJKSTRA, H. H. & A. G. BEU. 2018. Living scallops of Australia and adjacent waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae). Records of the Australian Museum, 70 (2): 113-330, figs. 1-102. [p. 237]
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