Is there any risk in a symbiotic species associating with an endangered one? A case of a phoronid worm growing on a Ceriantheomorphe tube

The conservation of emblematic threatened species is in highlight nowadays. Interestingly, few invertebrate groups attract scientific attention on this issue while they constitute the vast majority of animal biodiversity. Nevertheless, many invertebrate species are nowadays at risk of extinction. This means that plenty of species are currently disappearing out of sight. During a survey in the southwestern Atlantic Ocean tubes of an endangered species of cerianthid were sampled. This study reports for the very first time the occurrence of the species Phoronis australis in southwestern Atlantic waters and the association of phoronids with the genus Ceriantheomorphe. This raises questions on mutual extinction risks for symbiotic species and also on the criteria for their inclusion on Red Lists.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) through the Programa de Posgraduacao em Zoologia do Departamento de Zoologia (IBUSP, Universidade de Sao Paulo)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CNPq[481399/2007-0]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Petróleo Brasileiro S.A. (PETROBRAS)Financiadora de Estudos e Projetos (FINEP)MCT/FINEP/Acao Transversal-Cooperacao ICTs-Empresas (Petrobras)[06/2006 (3175/06)]Universidade de São Paulo - Laboratorio de Microscopie Electronica and of the Departamento (Enio Mattos) de Zoologia - IB-USPUniversidade de São Paulo - Laboratorio de Microscopie Electronica and of the Departamento (Enio Mattos) de Zoologia - IB-US