No. 1

The Black Intertidal or Purplish Bifurcate Mussel (English)

Murasakiinko (Japanese)

• Source of Report: Minamihama (South Beach), Shirahama, Japan
• Scientific name: Septifer virgatus (Wiegmann, 1837)
• Appearance: 2-3 cm in length with a solid elongated purplish black shell.
• Habitat: moderately exposed intertidal rocky shores
• Distribution: In Japan they are found from Southern Hokkaido to Kyushu but are also reported from Hong Kong
• Distinguishing Characteristics: In Japan it is often found with a the mussel Hormomya mutabilis (Gould) [Hibarigaimodoki] from which it is distinguished by having a less acute umbo and a thicker darker shell with less obvious ribs (they grow fainter with age) however they are clearly distinguished from H. mutabilis by the absence of a septum.
• Side Notes: During NaGISA sampling in Shirahama in August (2006), over 70% of the mid tide 1m x 1m quadrates were filled with these `purple` mussels.
• References: Okutani. T. 2000 Marine Mollusks in Japan 865p and Yamada Masako 2004 Shell`s Database Server http://shell.kwansei.ac.jp/