Ascidian (Chordata, Ascidiacea) diversity in the Red Sea

Although the Red Sea is considered as a center of endemism and a ‘hotspot’ of biodiversity, the ascidian fauna (Chordata, Ascidiacea) of the region has been poorly studied. The current study provides a review of the literature concerning the ascidian fauna of the Red Sea, including the Gulf of Aqaba and the Gulf of Suez, an updated species list based on extensive field sampling and museum data, and an analysis of the diversity and rates of endemism of the Ascidiacea of the Red Sea. The inventory lists 73 ascidian species, belonging to 13 families. The majority of species records are of colonial species, as typical of tropical regions. Representatives of 30 species are available at the National Collections of Natural History at Tel Aviv University. Only 12 species (17 %) of the Red Sea ascidians were found to be endemic to the region, whereas the majority have an extra Indo-Pacific distribution. Eight species have been recorded for the first time from this region. The Gulf of Aqaba and the Gulf of Suez represent the northern boundary of the natural distribution for the majority of tropical species recorded in this study. However, several species have successfully entered the Mediterranean Sea through the Suez Canal. This list is certainly incomplete and emphasizes the need to increase the sampling effort for this group, and for additional taxonomic studies of the ascidian fauna of this highly diverse and rich region.