Kotorapecten Masuda, 1962
MASUDA, K. 1962. Tertiary Pectinidae of Japan. Science Reports of the Tohoku University [2nd. Series - Geology], 33 (2): 117-238, pls. 18-27. [p. 216]
«Subgenus Kotorapecten Masuda, n. subgen.
Type-species: — Pecten kagamianus Yokoyama, 1923. Miocene Kimachi formation of Shimane Prefecture.
Geological distribution: — Miocene.
Diagnosis: — Shell large, moderately thick, rather compressed, suborbicular, subequivalve but sometimes somewhat inequivalve; right valve with rather distinct or sometimes rather low, rounded, broad radial ribs with rather distinct longitudinal threads, sometimes with rather indistinct intercalary threads; left valve with rather distinct, narrow radial ribs with longitudinal threads and sometimes intercalary threads; anterior auricle somewhat larger than posterior, with rather wide and shallow byssal notch; hinge with distinct but simple cardinal crura, wide and deep resilial pit provided with distinct lateral ridges, and sometimes with ctenolium but usually in younger stage; interior surface somewhat folded.
Remarks: — The present new subgenus is named in honor of Prof. Kotora Ratai of the Tohoku University.
This new subgenus includes the following species, that is, kagamianus (s. s.), kagamianus permirus, kagamianus moniwaensis, kagamianus nimaensis, yamasakii (s. s.), yamasakii iwasakiensis, yamasakii ninohensis, yamasakii kintaichiensis, tryblium, naganoensis, nakajimai and egregius. Patinopecten s. str. is distinguishable from the present one by its radial ribs without distinct longitudinal threads on their backs. Lyropecten Conrad (1862) also can be distinguished by its valves with a hump or wave on the umbo and by the hinge furnished with three, distinct, oblique divergent cardinal crura.» |
Pecten kagamianus Yok.; M. Yokoyama, 1923, On some fossil Mollusca from the Neogene of Izumo, plate 1, figures 1a, 1b.
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KÔICHIRÔ MASUDA, 1962