Published online by Cambridge University Press: 10 September 2010
A checklist of 53 soft-bottom species of polychaetes from the coastal lagoon Estero de Urías is presented here. Depth, sediment temperature, salinity, grain size, organic matter content, and dissolved oxygen ranges where polychaete species were found are provided. Twenty-six species are reported for the first time for the Estero de Urías coastal lagoon. This is the first report of the sabellid Amphicorina gracilis, the spionid Marenzelleria viridis, and the syllid Exogone (Parexogone) molesta for the Pacific coast of Mexico.