First record and evidence of an established population of the North American mud crab Dyspanopeus sayi (Brachyura: Heterotremata: Panopeidae) in the western Mediterranean

The panopeid crab Dyspanopeus sayi (Smith, 1869) is reported here from the Ebro Delta (Mediterranean coast of the Iberian Peninsula). Originally endemic to the Atlantic coast of North America, D. sayi was involuntarily introduced into Britain, France and the Netherlands, and into the Adriatic and Black Sea within the last thirty years. Here we provide the first record of this species from the western Mediterranean Sea. Occurrences of ovigerous females at different localities of the delta and in different years provide evidence that the population is well established. Mitochondrial DNA confirms the identity of the species and indicates that the introduced population consists of at least three female lineages. The first zoeal stage of D. sayi was obtained in the laboratory from an ovigerous female captured in August 2010 with embryos in an advanced stage of development. The morphology of the zoea I is described here in detail and is similar to the one previously reported for native populations.Travel funds to CDS and students were made possible through an exchange program of the DAAD (D/03/40344) and the Spanish Ministerio de Ciencia y Tecnología – Acciones Integradas (HA2003-078), with José A. Cuesta as Spanish collaborator. Florian Gmeiner, Silke Reuschel and Lapo Ragionieri assisted during field collections in 2005 and 2006 respectively and students at the University of Regensburg helped with the molecular work. Financial support to GG (post-doctoral fellowship; INIA) was provided by the Ministry of Science and Research. The authors would like to thank Agustí Benito, fisherman of Sant Carles de la Ràpita for his collaboration in catching crabs. PA acknowledges research project CGL2009-12912-C03-03 from the Ministerio de Ciencia e Innovación (Spain). Paul Clark kindly made available important literature and shared his own unpublished description of the first zoeal stage of Dyspanopeus sayi.