Relevant Synonyms - Misidentification Divaricella quadrisulcata Lamy, 1916 [Moazzo, 1939] Divaricella angulifera (Von Martens, 1880) [Mienis, 1979; Barash and Danin, 1986]  drawing: Tuvia Kurz

SHORT DESCRIPTION Shell, equivalve, equilateral rather inflated and thin. Outline circular. Lunule intermediate in length and much more developed in the rv. Sculpture divaricate of skewed rather narrow ribs. Angle of divarication 100-135°C. Four radial sulci on the anterior part. Ligament marginal. Hinge with two cardinal teeth in lv, one cardinal on rv. Lateral teeth obsolete. Inner margin minutely denticulate. color : ivory-white. common size : shell to 20 mm. Maximum in Red Sea 22 x 21 x 7 mm. DISTINGUISHING CHARACTERISTICS The species is differentiated from other Indo-West-Pacific Divalinga by the smaller size, thin shell obscure denticulated inner margin and relatively narrow ribs. D. arabica is most close to the American species D. quadrisulcata but differs from it in the thinner shell, the sharper angle of divarication and especially in the less developed lateral teeth (Dekker and Goud, 1994). BIOLOGY / ECOLOGY Infaunal siphonate, actively mobile, unattached animals found 2-3 cm deep buried in sand during low tide near the low water mark. Chemosymbiotic deposit feeders. habitat : in sand (quartz sand not coral sand) in shallow water; also in seagrass beds at depth 1-2 m.

1st Mediterranean record Israel, 1986 [1956]. DISTRIBUTION Worldwide: common in the Red Sea and the Arabian Gulf; also reported from the Gulf of Suez (Dekker and Goud, 1994). Mediterranean: reported first from Israel in 1956 as Divaricella angulifera (Barash and Danin, 1986) and in 1976 (Mienis, 1979); later in Egypt, off Bardawil (Barash and Danin, 1986). ESTABLISHMENT SUCCESS Established but rare. speculated reasons for success : - MODE OF INTRODUCTION Via the Suez Canal. IMPORTANCE TO HUMANS None.

KEY REFERENCES Barash A. and Danin Z., 1986. Further additions to the knowledge of Indo-Pacific mollusca in the Mediterranean Sea. Spixiana, 9(2): 117-141. Dekker H. and Goud J., 1994. Review of the living Indo-Pacific species of Divaricella sensu auct. with descriptions of two new species and a summary of the species from other regions. (Part 1). Vita Marina, 42: 115-136. Mienis H.K., 1979. Divaricella angulifera (von Martens, 1880), another Red Sea species from the Mediterranean coast of Israel. Levantina, 18: 200.   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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