Miyagipecten Masuda, 1952
MASUDA, K. 1952. On some Miocene Pectinidae from the environs of Sendai. Transactions and Proceedings of the Palaeontological Society of Japan [N. S.], 8: 249-254, pl. 24. [p. 251]
«Genus Miyagipecten MASUDA, n. gen.
Genotype:-- Miyagipectm matsumorieis MASUDA, n. sp.
Type locality:— Foot of the dam at Dogasawa, about 700 meters north of Matsumori, Nanakita-mura, Miyagi-gun, Miyagi Prefecture. Geological range:— Middle Miocene.
Diagnosis:— Shell of moderate size and thickness, subequivalve, equilateral, much compressed, suborbicular, exterior of right valve with only fine concentric growth lines, left with numerous weak, flatly raised, radial threads and fine concentric growth lines; radials becoming obsolete on lower half of disc, rarely associated with intercalary striae; interior surface smooth; hinge with strong cardinal crura and with small boss at each extremity: auricles of right valve subequal in size, anterior auricle with wide and shallow byssal notch.
Remarks.— Miyagipecten resembles the genus Placopecten VERILL, but the latter can be distinguished from the former by possessing similar sculpture on the surface of both right and left valves, though the right is smoother than the left, and by having a ctenolium in the young stage. Pseudamusium H. and A. ADAMS (1858, p. 553) also resembles the present genus, but can be distinguished therefrom by its smaller size, thinner test and weaker cardinal crura, possession of a ctenolium, well developed byssal notch and by exhibiting Comptonectes striation.» |
Myagipecten matsumoriensis Masuda, n. sp.; K. Masuda, 1952, On some Miocene Pectinidae from the environs of Sendai, plate 24, figures 4-7.
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KÔICHIRÔ MASUDA, 1952
Miyagipecten matsumoriensis Masuda; T. Matsubara, I. Noro, Y. Matsuura & T. Irizuki, 2014, Miocene Mollusca from the Ichibu Formation on Nishinoshima Island, Oki Islands, Southwest Japan figures 7.4, 7.8.
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«Subfamily Palliolinae Korobkov in Eberzin, 1960
Genus Miyagipecten Masuda, 1952
Type species.— Miyagipecten matsumoriensis Masuda, 1952 by original designation.
Discussion.— The systematic position of the genus Miyagipecten Masuda, 1952 is controversial. Masuda (1952) originally referred the genus to the subfamily Pectininae Rafinesque, 1815 based on the auricular crura with a distal denticle. Subsequently, Masuda (1957, 1962) regarded it as a genus in the subfamily Amusiinae Ridewood, 1903, which is currently reduced to the rank of a tribe of the subfamily Pectininae Rafinesque, 1815 (e.g. Waller, 2006, 2011). On the other hand, Hertlein (1969) regarded it as a subgenus of Chlamys [Röding], 1798 belonging to the subfamily Chlamydinae. Masuda (1986b) considered that Miyagipecten is closely related to the genus Lentipecten Marwick, 1928 (type species: Pecten hochstetteri Zittel, 1864), which is currently referred to the subfamily Palliolinae Korobkov in Eberzin, 1960 (Waller, 2006). Recently, Kurihara (2010) referred Miyagipecten Masuda, 1952 to the subfamily Chlamydinae, although he regarded its tribal status as incertae sedis, as well as that of Nipponopecten Masuda, 1962.
As a result of my reexamination of shell surface microsculpture of the type species, Miyagipecten matsumoriensis Masuda, 1952, it became obvious that the younger part of the left valve may have antimarginal microsculpture (Fig. 11). Based on the cardinal properties (Masuda, 1952, 1957) and the microsculpture, the genus Miyagipecten Masuda, 1952 would be referable to the subfamily Palliolinae Korobkov in Eberzin, 1960. Waller (2006) classified the subfamily Palliolinae into six tribes (Peudoentoliini Waller, 2006; Adamussiini Habe, 1977; Eburneopectinini Waller, 2006; Serripectinini Waller, 2006; Palliolini Korobkov in Eberzin, 1960; and Mesopeplini Waller, 2006). As the microsculpture in the preradial stage still remains unknown, further examination is needed to determine the origin and precise taxonomic status of the genus Miyagipecten Masuda, 1952.» MATSUBARA, T., I. NORO, Y. MATSUURA & T. IRIZUKI. 2014. Miocene Mollusca from the Ichibu Formation on Nishinoshima Island, Oki Islands, Southwest Japan. Paleontological Research, 18 (1): 6-32, figs. 1-11. [p. 22]
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