Relevant Synonyms Arca natalensis Krauss, 1848 Scapharca natalensis Misidentification Scapharca rufescens (Reeve, 1844)  photo: H. Niederhöfer / Coll. R. and L. Enzenross

SHORT DESCRIPTION Shell solid, strongly inequivalve. Almost equilateral; beaks close to midline. Outline quadrate, length almost equal to height; posterior margin straight, anterior and ventral margins curved. Sculpture of 27-30 wide, smooth radial ribs with interspaces a little narrower than ribs. Taxodont hinge with numerous teeth on a thin hinge plate in a straight line. Ligament with few distinct chevrons. Internal margin strongly crenulate. Periostracum of fine lamellae. color : dirty white with brown periostracum. common size : shell to 50 mm. DISTINGUISHING CHARACTERISTICS Differs from S. inflata (Reeve, 1844), a Red Sea species in size, shape and number of ribs: S. inflata shell up to 150 mm, rounded in profile and with 37 ribs. BIOLOGY / ECOLOGY Unknown. habitat : infralittoral zone, in sandy muds and muds in shallow waters (Oliver, 1992). In the Mediterranean shells dredged from 55 m (Barash and Danin, 1973).

1st Mediterranean record Palestine, 1937 [1935]. DISTRIBUTION Worldwide: Western Indian Ocean, Persian Gulf, Red Sea; recorded in the Suez Canal (Moazzo, 1939). Mediterranean: recorded first in 1935 from Gaza, Palestine (Haas, 1937); successively from Port Said and Port Fouad, Egypt (Moazzo, 1939); Iskenderun and Mersin gulfs (Enzenross et al., 1990). ESTABLISHMENT SUCCESS Common in Port Said and Port Fouad, moderately common in Bardawil, Egypt. speculated reasons for success : - MODE OF INTRODUCTION Via the Suez Canal. IMPORTANCE TO HUMANS None in the Mediterranean but similar species are consumed and commercially fished in southeastern Asia.

KEY REFERENCES Barash A. and Danin Z., 1973. The Indo-Pacific species of mollusca in the Mediterranean and notes on a collection from the Suez Canal. Israel Journal of Zoology, 21(3-4): 301-374. Barash A. and Danin Z., 1977a. Additions to the knowledge of Indo-Pacific Mollusca in the Mediterranean. Conchiglie, 13(5-6): 85-116. Enzenross L., Enzenross R. and Niederhöfer H.J., 1990. Wissenschaflich interssante Funde aus der Sammlung Enzenross (marine invertebraten). Jahreshefte der Gesellschaftten fuer Naturkunde in Wuerttemberg, 145: 283-294.   Haas G., 1937. Mollusca marina. Pp. 275-280. In: Bodenheimer F.S. (ed.). Prodromus faunae Palestinae, Mémoires de l'Institut d'Egypte. Oliver P.G., 1992. Bivalved seashells of the Red Sea. Christa Hemmen, Wiesbaden and National Museum of Wales, Cardiff, 330 p. FEEDBACK / COMMENTS TO AUTHORS

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