First report of the epizoic red alga Polysiphonia carettia (Hollenberg, 1971) on the loggerhead turtle Caretta caretta in the Adriatic Sea

Sea turtles are widely distributed in temperate and tropical seas, and their carapace is often colonized by species of macroalgae. There have been several studies on the epibionts of loggerhead turtles, Caretta caretta Linnaeus, from different parts of the world (KITSOS, et al., 2005; PFALLER et al., 2006, 2008). The carapaces of loggerhead turtles represent an important substratum for a variety of macroalgae (DODD, 1988). SENTÍES et al. (1999) reported 37 species of algae growing on loggerhead turtles found off the Caribbean coast of Mexico. Recently, FRICK et al. (2000; 2002; 2004), found 12 new records of previously undocumented epibiont species from loggerhead turtles nesting in Georgia, USA, while GARCÍA et al. (2003a,b) reported a total of 28 macroalgae on sea turtles from Oman (Arabian Sea). From the western Atlantic Ocean 33 species and 4 taxa were described by SENTÍES et al. (1999). To date only 20 species (and 2 taxa identified only at genus level) have been reported as epizoic on Mediterranean loggerheads (BÁEZ et al., 2002; KITSOS et al., 2005). The red alga Polysiphonia carettia (Rhodomelaceae, Rhodophyta) was described as new species by Hollenberg (HOLLENBERG, 1971). The type material, tetrasporic, was collected from the carapace of a Caretta caretta turtle from California. BÁEZ et al. (2001) reported the first record of P. carettia in the Mediterranean Sea as epizoic on C. caretta captured by a Spanish longline vessel south of Ibiza, Balearic Islands. Subsequently, SERIO et al. (2011) mentioned the presence of this species on the carapace of The authors report the first record of the red alga Polysiphonia carettia (Hollenberg, 1971) in the Adriatic Sea, collected from two loggerhead sea turtles Caretta caretta captured along the coast of the Savudrija peninsula (Croatia, Northern Adriatic Sea). The identification of the samples is based on both vegetative and reproductive tetrasporangial features. The morphological characters of the specimens studied are in agreement with previous reports of this species from other parts of the Mediterranean Sea.