Botryllid species (Tunicata, Ascidiacea) from the Mediterranean coast of Israel, with some considerations on the systematics of Botryllinae

Abstract

Several botryllid colonies of the genus Botrylloides from the Mediterranean coast of Israel are analysed. Three species are described: B. leachii, which differs because of its smaller size, from specimens collected from other European seas and is considered a case of dwarfism due to the particular hydrological conditions of the study area; B. anceps, a species originally described from the Indo-Pacific region, which probably migrated from the Red Sea; and Botrylloides israeliense, a new species. The distinction between the genera Botryllus and Botrylloides is discussed, and the original Milne-Edwards diagnosis based on differences in the structure of the system is recognised as still valid. Lastly, the diagnostic features usually employed in specific taxonomic determinations of Botryllinae are analysed.