Bractechlamys vexillum (Reeve, 1853)
REEVE, L. A. 1852-1853. Monograph of the genus Pecten. In: Conchologia
Iconica: or illustrations of the shells of molluscous animals , vol. 8. London [unnumbered pages], pls. 1-35. [pl. 27, fig. 114a-b]
1845 Pecten digitatus Hinds, 1845
1853 Pecten vexillum Reeve, 1853
1858 Pecten janus Montrouzier in Fisher, 1858
1935 Pecten zeteki Hertlein, 1935 [nomen novum pro Pecten digitatus Hinds, 1844]
1939 Bractechlamys evecta Iredale, 1939
1998 Bractechlamys georgei Dijkstra, 1998 [nomen novum pro Pecten distans G. B. Sowerby II, 1842]
1853 Pecten vexillum Reeve, 1853
1858 Pecten janus Montrouzier in Fisher, 1858
1935 Pecten zeteki Hertlein, 1935 [nomen novum pro Pecten digitatus Hinds, 1844]
1939 Bractechlamys evecta Iredale, 1939
1998 Bractechlamys georgei Dijkstra, 1998 [nomen novum pro Pecten distans G. B. Sowerby II, 1842]
L. A. Reeve, 1852-1853, plate 27.
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«PECTEN VEXILLUM. Pect. testa orbiculari, ad latera subimpressa, crassa, aequilaterali, subaequivalvi, valvis undique tenuiliratis et dense minutissime serratis, costis grandibus octo radiatis; valva sinistra carminea vel cinereo-grisea, albo promiscue maculata, valva dextra albida, carmineo punctata; auriculis aequalibus.
THE FLAG PECTEN. Shell orbicular, rather impressed at the sides, thick, equilateral, nearly equivalve, valves finely ridged and densely very minutely serrated throughout, rayed with eight large ribs; left valve carmine or ash-grey, promiscuously spotted with white, left valve whitish, dotted with carmine; ears equal. Hab. ——? A beautiful and very characteristic species, variously painted, although the painting above described is the prevailing colour.» LOVELL AUGUSTUS REEVE, 1853
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«Type material: Lectotype BMNH 197010, designated by Waller (1972: 243).
Type locality: Not mentioned in original description, although on labels of type lot "Australian Seas". Material from New Caledonia (MNHN), however, is very similar to the type specimens. A new type locality: Dot Maître, Noumea, New Caledonia, sandy bottom with seaweed,. 20 m (MNHN) of P. vexillum is here introduced. Material examined: The type material. PAPUA NEW GUINEA: PNG 1980: Hansa Bay, Mililat (N of Madang), small reef N, sandy slope and coral debris, hand· dredged, 12·15 m, leg. J. Pierret, 5.iii.1979, IG 26.080,1 valve. Distribution: Throughout the western and southwestern Pacific, from the Philippines, lndonesia, Papua New Guinea to New Caledonia. Living amongst seaweeds and coral rubble on muddy or sandy sediments in the littoral. Remarks: The present specimen is similar to the type material, although more triangular than suborbicular of shape, but intermediate variations are also observed (MNHN).» DIJKSTRA, H. H. 1998. Pectinoidea (Mollusca: Bivalvia: Pectinidae: Propeamussiidae) from Hansa Bay, Papua New Guinea. Molluscan Research, 19 (1): 11-52. [p. 17]
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Bractechlamys vexillum (Reeve, 1853); H. H. Dijkstra, 1998, Pectinoidea from Hansa Bay, Papua New Guinea, plate 2, figure 4.
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«Comparison
Mature Comptopallium vexillum resembles C. radula (Linnaeus, 1758) ( = C. pauciplicatum lredale, 1939) of intermediate size (35 to 45 mm in height; Figures 84, 85; Table 7). The latter species differs in having auricles which are larger relative to size of disk and which bear distinct radial costae, a narrower umbonal angle, and more flattened left valve particularly in the umbonal area, and in lacking the single denticle on the interior of each posterior auricle, possessing instead multiple denticles or radially elongate depressions on the auricular interiors. No other living species are closely comparable.
Remarks on Synonymy
The generic reassignment of Comptopallium vexillum to Semipallium as proposed by GRAU (1959, p. 122) and followed by HERTLEIN (1969, p. 366, in his treatment of Comptopallium as a junior synonym of Semipallium) is unacceptable because of strong differences in the morphogeny of shell microsculpture. The type species of Semipallium, Pecten tigris Lamarck, 1819, displays a fine shagreen microsculpture over almost its entire shell. Comptopallium vexillum and its congeners are densely lamellate and lack any trace of shagreen microsculpture.
Examination of the holotype of Pecten digitatus Hinds, and photographs of the holotype of Bractechlamys evecta Iredale leaves little doubt that these taxa are the same as Comptopallium vexillum. Ecology
Living habits: Although the living habits of Comptopallium vexillum have not been observed, the absence of a ctenolium and byssal gape on mature shells indicates that the species may lie free at this stage rather than attach byssally. This is further indicated by the lack of any byssal threads or byssal attachments among specimens preserved in alcohol. Young individuals, which have a distinct ctenolium and byssal gape, are probably byssally attached.
Museum collections show the species to be most numerous and to reach its maximum size along the shores of New Caledonia, New Guinea, and Mindanao. Specimens from these areas are associated with terrigenous fine sand, silt, or mud, commonly in association with marine grasses, coral rubble, and rocks and commonly occur in depths of a few feet. In contrast to the large-sized individuals from these areas, all specimens from the Marshall Islands are small, the largest attaining a height of only 24 mm and the majority being less than 15 mm, and they are found deep in the lagoons. Depth records of live specimens: From a few feet to 30 fathoms. Geographic distribution: In the western Pacific, from the Sulu Sea to New Guinea, the Palaus, Carolines, Marshalls, Solomons, and New Caledonia (Figure 5). Fossil Records
No fossil records of Comptopallium vexillum are known.»
WALLER,
T. R. 1972. The Pectinidae (Mollusca: Bivalvia) of Eniwetock Atoll,
Marshall Islands. The Veliger, 14 (3): 221-264, pls. 1-8. [p. 245, 246]
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Comptopallium vexillum (Reeve, 1853); T. R Waller, 1972, The Pectinidae of Eniwetock Atoll, plate 4, figures 64-75 (above); plate 5, figures 76-83, 86 (below).
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«Remarks [Semipallium zeteki (Hertlein) 1935]: No species even remotely resembling Hinds' Pecten digitatus has ever been found in the eastern Pacific. In view of the known confusion as to the actual localities of a number of his species (see Remarks under Chlamys hastata, this paper), we can be almost certain that the holotype of Pecten digitatus was collected in the western Pacific during the voyage of the Samarang, and is actually a juvenile specimen of Semipallium vexillum (Reeve).» [p. 123]
(...) «Remarks [Chlamys hastata (Sowerby) 1842]: Bavay's diagnosis of Pecten denticulatus Adams & Reeve (Borneo; Sulphur expedition) as a juvenile Chlamys hastata was undoubtedly correct. No species even remotely resembling the description and figure of P. denticulatus has been reported from the western Pacific; furthermore, while Adams and Reeve believed their species to have been collected during the voyage of the Samarang in that area, it has been established that Captain Belcher, who was on both the Sulphur and Samarang expeditions, mixed a number of shells from both.» [p. 86, 87] GRAU, G. 1959. Pectinidae of the eastern Pacific.
Allan Hancock Pacific Expeditions, 23: i-viii, 1-308, 57 pls.
University of Southern California Press. Los Angeles, California. [p.
123; 86, 87]
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Fig. 1, Semipallium zeteki (Hertlein) (? = Pecten vexillum Reeve, 1853.) Reproduction of original figure of Pecten digitatus Hinds, 1945; Fig. 2, Semipallium vexillum (Reeve), 1853. Left valve of juvenile for comparison with fig. 1; G. Grau, 1958, Pectinidae of the eastern Pacific, plate 41.
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