Cyclopecten almirantensis (Olsson, 1922)
OLSSON, A. A. 1922. The Miocene of Nothern Costa Rica with notes on its general stratigraphic relations. Bulletins of American Paleontology, 9 (39): 177-483, pls. 1-32. [p. 375, pl. 18, fig. 16]
1922 Pecten (Pseudamusium) [sic] almirantensis Olsson, 1922
A. A. Olsson, 1922, plate 18.
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«Shell small, thin, compressed or but slightly convex; the posterior and anterior dorsal slopes are straight, meeting the beaks at an acute angle; the right valve is finely sculptured with close, regular, concentric lamellae and wider interspaces; the posterior and anterior sides show a few, irregular, radial threads which cross the concentric lamellae; the ears are unfortunately broken; the interior of the shell cavity is filled with a thin deposit of callus; ventral margin plain; hinge line minutely grooved with vertical lines.
Length 4.75, height 4.75, diameter of right valve 60 mm.
This small, elegant species is represented solely by an imperfect right valve and represent the first true Pseudamussium to be discovered in the Miocene beds of Panama. Its sculpure is like the recent deep water Pseudamussiumn strigillatum Dall from the West Indies, but differs in having its anterior and posterior dorsal submargins meeting at the beaks at a much more acute angle. Gatun Stage: Bocas del Toro.»
AXEL ADOLPH OLSSON, 1922
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«Cyclopecten almirantensis (Olsson, 1922), known only from a right valve from the Bocas del Toro basin of Panama (probably from the Pliocene Caya Agua Formation; Collins, 1993: 708) is small in size and has a single internal lateral disk rib on each side, but differs from C. zalaya n. sp. in many other characters: costate auricles; radially aligned nodes on the prismatic calcite layer of the right valve; commarginal prism bands that alternate between tiny polygonal prisms and larger, radially elongate prisms; lateral internal aragonitic ribs that have calcitic cores (because their termini are within the foliated-calcite marginal secretion band on the shell interior); and less well-developed vertically ridged apposition zones on its hinge plates.
Cyclopecten thalassinus (Dall, 1886), an extant species with a broad geographic range in the tropical and temperate western Atlantic and a depth range from 40- >500 m (Abbott, 1974: 449; Theroux & Wigley, 1983), is a close living counterpart of C. almirantensis and differs from C. zalaya n. sp. in the same manner. In addition, C. thalassinus commonly has sculpture of high relief on its left valve.» WALLER, T. R. 2011. Neogene Paleontology of the Northern Dominican Republic. 24. Propeamussiidae and Pectinidae (Mollusca: Bivalvia: Pectinoidea) of the Cibao Valley. Bulletins of American Paleontology, 381: 1-197, pls. 1-18. [p. 24]
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