Re-identifications of Two Freshwater Pearl Mussel Species Distributed in the Kamchatka-Sakhalin-Kuril-Japan Region Based on Morphological Comparison of Type Specimens (Bivalvia: Margaritiferidae)

摘要

Previous taxonomic and molecular studies demonstrated the existence of two distinct species of the freshwater pearl mussel genus Mararitifera in the Kamchatka-Sakhalin-Kuri 1-Japan region, but problems remained as to their identilication. To solve them, shells of nominal types and other voucher specimens were reexamined morphologically in detail and compared with Japanese populations using multivariate analyses. The results reconlirmed the importance of the shape of the dorsal edge of the anterior adductor muscle scar, and demonstrated the usefulness of the width of pseudocardinal teeth as a distinguishing character. Based on the results the previously accepted classification was revised: M. laevis (Haas, 1910) (Japanese name: Kawa-shinju-gai) is characterized by a rounded dorsal edge of the anterior adductor muscle scar and thin pseudocardinal teeth, and M. kurilensis (Zatravkin & Starobogatov, 1984) (Japanese name: Kogata-kawa-sninju-gai) is characterized by an ungulate dorsal edge of the anterior adductor muscle scar and robust pseudocardinal teelh. Margantifeni middendorffi (Rosdn, 1926), a name often applied to the latter species, is here considered a junior synonym of M. laevis, and M. togakushiensis Kondo & Kobayashi, 2005, often synonymized with M. middendorffi, is shown to be a junior synonym of M. kurilensis, judged From the morphology ol' the primary types.