Amussiopecten yabei (Nomura, 1933)
NOMURA, S. 1933. Catalogue of the Tertiary and Quaternary Mollusca from the Island of Taiwan (Formosa) in the Institute of Geology and Paleontology, Tohoku University, Sendai Japan. Part 1, Pelecypoda. Science Reports of the Tohoku University [2nd. Series - Geology], 16 (1); 1-108, pls. 1-4. [p. 59, pl. 2, figs. 3, 4]
1933 Pecten (? Amussiopecten) yabei Nomura, 1933
S. Nomura, 1933, plate 2.
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«Shell resembling P. praesignis of the Japanese Neogene in general aspect; they are rather large, subcircular, compressed, slighly longer than high, subequivalved. Outside of ribs appearently low and flattish. Interior of the disc ornamented with about 15 pairs of sharp ribs which are almost equally spaced. Ears rather large and subequal being rectangular. Length, ca. 47 mm.: height 43 mm.
A few specimens which are moulds were examined. So far as the internal ribs are concerned, the present species differs from P. praesignis in having a greater number. This fact has already been pointed out by Mr. T. KURODA. On the other hand, it is closely related to P. (Vola) gendinganensis MARTIN and P. (Vola) singkinensis MARTIN¹ from the Miocene of Java, though definitely distinguished from the two; it may represent a distinct species. Fossil occurrence: Kaizan Beds.— Mingetsu; Reg. No. 37392. Near Rahau, Banchi; Reg. No. 25265. Hokuzankô; Reg. No. 21109.» ¹ MARTIN: Foss. von Java, 1906-1922, p. 354, PI. 51, figs. 71, 72, p. 354, PI. 50, figs. 69; PI. 51, fig. 70.
SHICHIHEI NOMURA, 1933
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«The present species is characterized by its medium-sized, a little inflated right valve having 16 to 18 rather low and flatly round-topped radial ribs which tend to become obsolete towards ventral margin and somewhat lamellated, rather distinct incremental lines, a little inflated or nearly flat left valve with radial ribs which are distinct at upper part but tend to become low and broad and to become obsolete towards ventral margin, and distinct well developed internal ribs.
Amussiopecten akiyamae Masuda (1962A) described from the Miocene Inagozawa Formation (= Senhata Formation) in Chiba Prefecture, central Japan, is closely related with the present species, but akiyamae can be distinguished from yabei by its rather large shell, fine longitudinal striae on radial ribs and interspaces between radial ribs on lower part of disc. Also the present one can be distinguished from Amussiopecten iitomiensis (Otuka) (Akiyama, 1957) in the Miocene Shizukawa Formation, Yamanashi Prefecture, central Japan, by its larger number of radial ribs, and different from Amussiopecten singikirensis (Martin, 1910) in the Miocene of Java, Indonesia, by its fewer number of more distinct radial ribs, simple and less distinct cardinal crura and more distinct internal ribs. The occurrence of this species marks the early-middle Miocene age in northern Taiwan (Huang and Cheng, 1983).» MASUDA, K. & C. HUANG. 1990. Miocene Pelecypoda in the western foorhills of northern Taiwan (Part II. Sistematyc description). Bulletin of National Museum of Natural Science, 2: 141-189. [p. 149]
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Amussiopecten yabei (Nomura, 1933); Masuda, K. & C. Huang, 1990, Miocene Pelecypoda in the western foorhills of northern Taiwan, plate 4, figures 15-19.
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