Victoripecten victoriensis (Crespin, 1950)
CRESPIN, I. 1950. Some Tertiary pelecypods from the Lakes Entrance oil shaft, Gippsland, Victoria. Proceedings of the Royal Society of Victoria, 60: 149-156 [p. 151, pl. 15, figs. 8-11]
1950 Lentipecten victoriensis Crespin, 1950
I. Crespin, 1950, plate 15.
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«Holotype. Shell, brown in colour, moderately large, compressed, thin, polished, suborbicular. Right valve gently convex. Surface covered with very fine concentric lines. Stronger concentric growth lines towards periphery. Ears equal in size, covered with fine almost vertical lamellae and with straight dorsal margin. Left valve almost flat, with slight convexity in area immediately below umbo. Surface covered with very fine concentric lines, with strong concentric growth lines towards periphery. Faint, flat radial ribs on anterior and posterior just below hinge line. Ears unequal, covered with lamellae which are curved on anterior ear. Margins curved. Lamellae form a serrated fringe on slightly curved dorsal margin. Posterior slightly larger than anterior.
Height, 73 mm. ; length 75 mm. ; thickness of two valves, 15 mm. Paratype. Right valve. Shell broken, but all external characters as in holotype. Internal surface of shell smooth. Adductor scar large. Height, 68 mm. ; length, 68 mm. ; thickness of single valvfe, 5 mm. Observations. Tate referred a smooth shell from the Australian Tertiaries to the New Zealand Tertiary species Pecten hochstetteri Zittel, but Marwick (1924) stated that Tate was mistaken in thinking that species had two smooth valves. The smooth form from New Zealand is P. huttoni Park. There is little doubt that the Australian form is a new species and distinct from the New Zealand one. Consequently a new name Lentipecten victoriensis is given to the shell referred by Tate to P. hochstetteri. Numerous specimens of L. victoriensis were present in the micaceous marls and sandy marls of Janjukian age in the Lakes Entrance Shaft, but because of the fragile nature of the shell complete specimens were difficult to collect. Valves were also present in the hard bands of concretionary sandstone, which are characteristic of the Janjukian Stage in the Lakes Entrance area. Occurrence. Holotype from brown micaceous marls at 1,020 to 1,060 feet. Comm. Pal. Coll. No. F.16,098, Type No. 632. Paratype at similar depth. Com. Pal. Coll. No. F.15,449, Type No. 633. Age. Middle Miocene (Janjukian Stage).» IRENE CRESPIN, 1950
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«Occurrence and time range. Aldingan to Bairnsdalian; although there are few Balcombian and Bairnsdalian records and, as noted above, Late Eocene-Early Oligocene specimens from the St Vincent Basin possibly represent an unnamed, ancestral species. Common at Janjukian and Longfordian localities in the Otway, Murray and St Vincent basins; one valve seen from the Longfordian Abrakurrie Limestone in the Eucla Basin. It is abundant in pure limestone lithologies, and uncommon to rare in terrigenous ones. It is very much the most abundant pectinid at many Mannum Formation localities along the Murray River, but is absent from the overlying Morgan Limestone (in which the only pectinid with a smooth exterior is Amusium morganense sp. nov.).
Remarks. Victoripecten victoriensis is very easily identified among Australian fossil scallops, because it is the only species with an almost circular, completely smooth (to the naked eye), polished exterior, and no internal rib carinae. Confusion with Amusium when the interior is not visible is much less of a problem than might be expected, as the two genera occur together only in Jan Juc Formation at Bird Rock cliffs, Torquay, Victoria (type Janjukian) and in Mannum Formation (Longfordian) on the Murray River, South Australia, and the species of Amusium occurring in both these formations is A. subcostatum sp. nov., with very weak radial costae on the exterior. Most specimens of V. victoriensis have 4-6 low but obvious radial costae on the proximal area of the RV auricle, fading out over the distal area; such RV auricle radials are present on a few specimens of the Miocene ‘aff. Lentipecten' in New Zealand, but are not present on most specimens. The holotype of V. victoriensis also has 5 weak, obscurely defined radial costae on the distal part of the RV posterior auricle, but these are not present on many other specimens. The overall shape of the auricles is also quite variable; they have strongly convex anterior and posterior margins on the holotype and many other specimens, but on other (mostly smaller) specimens they have much straighter margins and a more nearly square appearance. The raised, strongly convex dorsal auricular margin on the RV, strongly serrated by growth ridges, also adds to the rounded appearance of RV auricles, but of course LVs have straight dorsal margins, as in all other pectinids. The superficially similar RV of Serripecten semilaevis reaches a larger size than that of V. victoriensis, and also differs in its much wider umbonal angle, in its more inflated disc, in its much lower and wider, much more strongly serrated auricles, in lacking the obvious gill-suspensor muscle scars, and in its deeper byssal notch. Of course, this smooth valve is also always associated with the finely and evenly scaly LV of Serripecten. S. semilaevis also occurs in younger rocks than V. victoriensis (most records are Bairnsdalian). Eocene and Early Oligocene records of Victoripecten are few, and their status is unclear. A total of only about 15 specimens has been seen (Fig. 42D) that are older than Janjukian, from Tortachilla Limestone and Port Willunga Formation in the St Vincent Basin. They are. all markedly smaller than Janjukian-Longfordian adults (to c. 45 mm high), and a few RVs are well enough preserved to demonstrate that they retain a functional ctenolium at this height (Fig. 42B, D). However, adult RVs of V. victoriensis from Janjukian-Longfordian rocks also retain a functional ctenolium until about this height, although it appears to have been lost before adulthood by all Janjukian-Longfordian specimens. In view of the few specimens seen, it is unclear at present whether these pre-Janjukian specimens represent an unnamed, smaller, ancestral species, or are simply immature. At present we see no justification for recognising more than the one species, V. victoriensis.» BEU, A. G. & T. A. DARRAGH. 2001. Revision of southern Australian Cenozoic fossil Pectinidae (Mollusca: Bivalvia). Proceedings of the Royal Society of Victoria, 113: 1-205. [p. 125, 127]
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Victoripecten victoriensis (Crespin); A. G. Beu & T. A. Darragh, 2001, Revision of southern Australian Cenozoic fossil Pectinidae, figure 42 (above), figure 43 (below).
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