Annachlamys suvaensis (Mansfield, 1926)
MANSFIELD, W. C. 1926. Fossils from quarries near Suva, Viti Levu, Fiji Islands, and from Vavao, Tonga Islands, with annotated bibliography of the geology of the Fiji Islands. Papers from the Department of Marine Biology of the Carnegie Institution of Washington, 23: 85-104, pls. 1-7. [p. 89, pl. 4, figs. 2a, 2b]
1926 Pecten (Chlamys) suvaënsis Mansfield, 1926
W. C. Mansfield, 1926, plate 4.
|
«The shell is of medium size, orbicular, solid, equilateral, moderately inflated over the disk, and slightly compressed medially at and near the beak. The disk is radially sculptured by 18 low-keeled, nearly rounded ribs with interspaces of about half their width, in which there is a low, medial thread, becoming more prominent on nearing the margin; submargins about 3 mm. wide, without radial ribs; whole surface of shell ornamented with close-set, threadlike, concentric sculpture, becoming crowded and imbricated near and at the margins. Ears nearly equal, anterior ear slightly broken away at the byssal area, radially marked with low ribs. the anterior with 5, the posterior with 4, all overrun by fine. close-set imbrications. Type, right valve (U. S. Nat. Mus. Cat. no 352415), measures: length, 50 mm., est. (25 mm. from posterior margin to middle between 9th and 10th ribs); height, 45 mm.; thickness, 8 mm.
Type locality: 1/132. About 200 feet above sea level. A fragment from station 4370 belongs to the same species and possibly is from the same quarry as the type. The new species here described is related to P. leopardus Reeve.² In comparison with Reeve's figure, the ribs are found to be more diverging and without a medial keel, the interspaces wider and lacking the interradial thread, than in the new species. K. Martin³ identified forms with P. leopardus Reeve and gave its geological range⁴ "Miozän u. vermutlich pliozän; rezent."» ² Reeve. Conch. Iconica, vol. VIII. Monogr. of the genus Pecten, pI. XXXII, fig. 145, 1853.
³ Die tertiarschichten auf Java, Leiden, p. 123, Tab. 20, fig. 8, 1880. ⁴ Unsere Palaezoologische Kenntnis von Java. Samml. Geolog. Reichs-Mus. Leiden, Beilage-Bd., p. 58, 1919. WENDELL CLAY MANSFIELD, 1926
|
«The fossil record of Annachlamys appears to be limited to the Neogene (Miocene to Pleistocene) of the Indo-Pacific region. Examples are Annachlamys okinawaensis Noda, 1991, from the Ryukyu Islands, southwest Japan, Pecten (Chlamys) suvaënsis Mansfield, 1926, and Pecten (Chlamys) nausorensis Ladd, 1934 from the late Miocene or early Pliocene of the Fiji Islands, and Pecten murrayanus Tate, 1886, from the Morgan Limestone of South Australia. The last species is possibly the oldest known Annachlamys.»
WALLER, T. R. 2006. New Phylogenies of the Pectinidae (Mollusca: Bivalvia): reconciling Morphological and Molecular Approaches. In S.E. Shumway & G.J. Parsons (Ed.) 2006: Scallops: Biology, Ecology and Aquaculture, 1-44. [p. 27]
|
«The interior characters are not well shown Dn the holotype, but a topotype (B. P. Bishop Mus., Geol. no. 1101), a right valve, shows that the resilium pit is large, deep, and sharply set off from the adjoining areas, though not bordered by a distinctly elevated ridge. Two prominent cardinal crura diverge from the apex of the pit on either side and tend to parallel the hinge border; the upper pair extend to the edge of the auricles, but the lower ones are only half as long. The cardinal edge of the auricles is bent downward. The external ribbing is strongly impressed on the interior as a series of low, broad radial ribs and equally wide interspaces, the ribs having thickened borders. Another right valve (B. P. Bishop Mus., GeoI. no. 1102) (pI. 27, figs. 3, 4) is from a slightly older horizon and is thinner and smaller than the type. It appears to be a young shell, and the spaces between the ribs fail to show the median thread which is present near the margins of the larger shells. In other respects it agrees with the type except that the anterior ear carries six ribs and is slightly higher than in the type. The left valve of this species is unknown.
Topotype (B. P. Bishop Mus., GeoI. no. 1101): length 50.7 mm., height 46.7 mm., depth 8.0 mm. Homeotype (B. P. Bishop Mus., GeoI. no. 1102): length 31.4 mm., height 31.4 mm., depth 4.6 mm. Localities: type from Station 295 (Mansfield's Station 1/132); also collected from Stations 320, and 133, the latter being a questionable identification. As Mansfield has pointed out, P. suvaensis is related to P. leopardus Reeve, but the ribs of the latter are more diverging and lack a medial keel, and the interspaces are wider and lack the median thread. According to Van der Vlerk (Leidsche Geolog. Mededeel. vol. 5, p. 268, 1921), P. leopardus has been reported from the Neogene of Madoera, the Miocene and Pliocene (?) of Java, the Pliocene and Quaternary of Timor. It is possible that P. suvaensis does not belong to the subgenus Pecten. The left valve is unknown and the right valve lacks the numerous radial threads of the type species. It seems closer to Pecten sensu stricto, however, than to Chlamys, where it was originally placed. The gently sloping dorsal margins, the subequal ears, and the equilateral outline do not suggest Chlamys. It should also be pointed out that the right valve is not deeply indented, there is no ctenolium, and there are at least two pairs of prominent cardinal crura.» LADD, H. S. 1934. Geology of Vitilevu, Fiji. Bernice P. Bishop Museum Bulletin, 119: 1-263, pls. 1-44. [p. 171, 172]
|
Pecten (Pecten) suvaensis Mansfield; H, S. Ladd, 1934, Geology of Vitilevu, Fiji, plate 27, figures 1-4.
|