Relevant Synonyms Bursatella savignana Aouduin, 1826 Notarchus laciniatus Rüppell and Leuckart, 1828 Aclesia freeri Griffin, 1912 Bursatella leachii leachii [Palermo] Bursatella leachii savignyana [Palermo] Misidentification -  photo : L. Mizzan

SHORT DESCRIPTION Slug like mollusc covered all over with simple and compound villi (papillae) of unequal size, giving it a ragged appearance. Head short and broad, with many branched median villi. Oral tentacles broad and projecting laterally. Foot broad, with a short acute tail. Parapodia short, not very mobile, their edges recurved and fused posteriorly high up, bearing a row of simple villi. A large arcuate ctenidium usually protudes through the dorsal slit. color : dull brown or greenish brown, with reticulate markins, black spots and clear, brighter green areas, each with a peacok-blue ocellus (sometimes absent). Inner edges of the parapodia, mantle cavity and pedal sole paler. common size : usually from 50 to 100 mm, up to 150 mm. DISTINGUISHING CHARACTERISTICS Eales and Engel (1935) reviewed the genus Bursatella and considered that there was a single species world-wide, B. leachii, which for convenience they divided into several geographical subspecies. Here we do not recognize this sub-division and treat the Mediterranean subspecies B. leachii leachii and B. leachii savignyana as synonyms. BIOLOGY / ECOLOGY The population numbers of this species fluctuate sporadically. Thousands of individuals can be present in a small area of a lagoon, in very dense aggregations, but may be entirely absent a few weeks later. Individuals seem to form a chain when copulation occurs (mainly in the late summer and autumn). Each specimen acts as a male (sperm donor) to the one in front, and as a female (sperm recipient) to the one behind. The egg masses consist of a tangled string, yellow-orange in color, adhered to the substratum. Each egg capsule within the jelly matrix of the string encloses from two to 20 embryos. The planktotrophic veligers hatch 7-8 days after ovoposition (at 25 °C) and they can delay the metamorphosis up to 2-3 month, until an adequate substratum for settlement is found. This extended time of the larvae in the plankton confers a high dispersal ability to the species. From gut contents, Bursatella leachi seems to be a deposit feeder with grazing habits (Russo, 1987). habitat : in the Mediterranean usually found in soft bottoms covered by Caulerpa prolifera or by Cymodocea nodosa and Zostera noltii.

1st Mediterranean record Palestine, 1940 [no collecting date]. DISTRIBUTION Worldwide: circumtropical. Mediterranean: recorded first from Palestine (O'Donoghue and White, 1940); successively recorded in Turkey (Swennen, 1961); Malta (Bebbington, 1970); Israel (Eales, 1970); Sicily (Piani, 1980); Tunisia (several records from the Gulf of Gabès since 1982, Enzenross and Enzenross, 2001); Italy (Fasulo et al., 1984 as B. leachii and B. l. savignyana); Slovenia (Jaklin and Vio, 1989); Greece (Koutsoubas, 1992); Lebanon (collected by G. Bitar and H. Zibrowius, identification confirmed by J. Templado); Sardinia (collected by A. Olita, identification confirmed by J. Templado). ESTABLISHMENT SUCCESS Very common from the eastern Levantine Sea to the Italian coasts; in the western Basin, only known from an area between Sicily, Naples and Sardinia. speculated reasons for success : - MODE OF INTRODUCTION Either by ships from the tropical Atlantic or via the Suez Canal. IMPORTANCE TO HUMANS None.

KEY REFERENCES Eales N.B., 1970. On the migration of Tectibranch molluscs from the Red Sea to the Eastern Mediterranean. Proceedings of the Malacological Society of London, 39: 217-220. O'Donoghue C.H. and White K.M., 1940. A collection of marine molluscs, mainly opisthobranchs, from Palestina. Proceedings of the Malacological Society of London, 24: 92-96. Russo G.F., 1987. Segnalazione di Bursatella leachi De Blainville, 1817 (Mollusca, Opisthobranchia, Aplysiomorpha) per le acque dell'isola d'Ischia e considerazioni sull'ecologia della specie. Bollettino della societa Naturalisti in Napoli, 94: 243-253, fig. 2, tav. 1.   FEEDBACK / COMMENTS TO AUTHORS

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