Epibiont algae on Mediterranean Caretta caretta Linnaeus from Aeolian Archipelago (Sicily, Italy).

Algae are common epibionts on the carapace of the sea turtles. Despite this, most of the papers on marine species concern the animal component. The flora of the loggerhead turtle, Caretta caretta, is one of the best-studied. However, the data on Mediterranean individuals of this species are limited in number and are prevalently restricted to few areas. Here we report the results obtained studying 41 individuals of Caretta caretta from the Aeolian Archipelago (Sicily, Italy). Yearly boat-based surveys were conducted in an area of about 280 Kmq around Filicudi Island and specimens were obtained from October 2015 to January 2017. A total number of 16 species of algae were sampled and identified. They belong to 4 different classes: 9 species to the Cyanobacteria, 2 to the Chlorophyta, 4 to the Rhodophyta and only one to the Ochrophyta. Some of these species are reported for the first time as epibionts on C. caretta carapace. Their frequencies on the individuals are reported. Our data on the Cyanobacteria represent the only contribution to species of this phylum growing on the Mediterranean sea turtles. Seven of these species have been found for the first time on the carapace of C. caretta and one of these, Chroococcidiopsis polansiana Andersen in Komárek & Anagnostidis, is the first record for the Mediterranean Sea. Two species of the genus Ulvella Crouan P. and Crouan H. (Chlorophyta) have been reported for the first time on a sea turtle. On the morpho-anatomical bases, only an individual referable to Ochrophyta was collected on the carapace of the studied turtles. Our preliminary data suggest that this specimen could be assigned to the Fucales. No species of this order have been collected from the carapace of a turtle. Among the Rhodophyta, Acrochaetium corymbiferum (Thuret) Batters and Acrosorium ciliolatum (Harvey) Kylin were reported for the first time on a turtle. A Polysiphonia sp., representing the species more abundant on the carapace of our turtles, presented several morphological similarities with P. carettia Hollenberg and Melanothamnus cheloniae (Hollenberg & J.N. Norris) Díaz-Tapia & Maggs. About these individuals, molecular data suggest to ascribe them under the genus Melanothamnus.