First records of the non-indigenous green algal species Siphonocladus tropicus (Cladophorales, Chlorophyta) and Caulerpa integerrima (Bryopsidales, Chlorophyta) in the Mediterranean Sea. First records of Siphonocladus tropicus and Caulerpa integerrima in the Mediterranean Sea

We provide an account of two newly recorded non-indigenous tropical seaweed species, Siphonocladus tropicus (Cladophorales, Chlorophyta) and Caulerpa integerrima (Caulerpaceae, Chlorophyta), from the northern and central Levantine Mediterranean shores of Israel, based on morphological and molecular evidence. Global warming and the tropical climate that the eastern Levantine Sea acquired in recent years probably paved the way for their establishment in the region. Siphonocladus tropicus, which lately started to show invasive features along the Israeli northern shore, is also being reported from the northern Red Sea. Furthermore, morphological comparison of populations from the northern Red Sea and the Levantine Mediterranean shore of Israel revealed that there might be a regional variant or form of this species in the northern Red Sea and might also indicate that this new invader does not necessarily originated from the Red Sea . The new record of C. integerrima increases the number of non-indigenous Caulerpa species in the Mediterranean Sea to six. Aspects of the new invaders’ ecology in the Israeli Levantine Sea, the possible vectors of introduction and origins as well as the status of other Caulerpa species from both Levantine and Red Sea shores are discussed.