Recent strandings of the giant jellyfish Rhizostoma luteum Quoy and Gaimard, 1827 (Cnidaria: Scyphozoa: Rhizostomeae) on the Atlantic and Mediterranean coasts

We present reports of sightings of living and stranded specimens of Rhizostoma luteum on the Atlantic coast of Morocco and along the south shore of the Iberian Peninsula in June–July 2012 and in January–February 2013. During summer 2012 and following the dominant currents, the jellyfish first appeared in the Gulf of Cadiz west of the Strait of Gibraltar. Subsequently, seven additional sightings were reported east of the Strait, in the Alboran Sea. In winter 2013, another event of stranded individuals of this species occurred in the Gulf of Cadiz. A phylogenetic analysis performed on the mitochondrial cytochrome c oxidase I (COI) gene sequence in specimens from both stranding events confirmed the morphological classification, ratifying that R. luteum differs from Rhizostoma octopus and Rhizostoma pulmo. This study records the presence of this species for the first time in 60 years.This work was financially supported by Spanish MIC Plan Nacional Project JELLY-PHYS (CTM2011-22586), Ministerio de Agricultura, Alimentación y Medio Ambiente (049/2010), Consejería de Ciencia, Innovación y Empresa Junta de Andalucía (Observatorio del Estrecho), E.U. MarinERA Project MedEX (CTM2008-04036-E/MAR), PERSEUS (FP7-287600). A research grant to L. P. from Ramón y Cajal Programme of the Spanish MIC and a JAE-Doc contract (#X0SC000087) to D. M. from the Spanish Council for Scientific Research (CSIC) are also acknowledged.Peer Reviewe