Comparative phylogeography of two symbiotic dorvilleid polychaetes (Iphitime cuenoti and Ophryotrocha mediterranea) with contrasting host and bathymetric patterns Patricia Lattig (PL)1, Isabel Muñoz (IM)2, Daniel Martin (DM)3, Pere Abelló (PA)4, Annie Machordom (AM)1 1 Museo Nacional de Ciencias Naturales (MNCN-CSIC), C. José Gutiérrez Abascal 2, 28006, Madrid-Spain 2. Instituto Español de Oceanografía, Centro Oceanográfico de Santander (IEO). Promontorio San Martín s/n. 39004, Santander (CANTABRIA)-ESPAÑA 3. Centre d’Estudis Avançats de Blanes (CEAB–CSIC), Carrer d’accés a la Cala Sant Francesc 14, 17300 Blanes (Girona), Catalunya, Spain. 4. Institut de Ciències del Mar (ICM-CSIC), Passeig Marítim de la Barceloneta, 37-49. E-08003 Barcelona, Catalunya, Spain. Corresponding author: PL. Museo Nacional de Ciencias Naturales (MNCN-CSIC), C. José Gutiérrez Abascal 2, 28006, Madrid-Spain. Corresponding mail address:
[email protected], fax: 915645078 Running tittle: Phylogeography of two crab-associated Dorvilleidae Abstract Two symbiotic polychaetes living in brachyuran crabs in the western Mediterranean and nearby Atlantic were analysed to determine their phylogeographical patterns and the possible effects of known oceanographic barriers in the study area. The analysed species live in hosts inhabiting well-differentiated depths, a factor which may be crucial for understanding the different patterns observed in each species. Iphitime cuenoti was found in four different host crabs between 100 and 600 m depth and showed some level of genetic homogeneity, reflected in a star-like haplotype network. Furthermore, barrier effects were not observed. In contrast, Ophryotrocha mediterranea was exclusively found in a single host crab species living between 600 and 1200 m depth.