Abstract: The first record of Ambidexter symmetricus from the Yucatán Peninsula is herein reported; extending the geographic range of the species to the southeastern Gulf of Mexico. During monthly visits to Seybaplaya, Campeche in 2014, a total of 13 specimens were collected from May to November; 1 specimen was male and the rest were ovigerous females, suggesting that this species has a continuous reproduction.

Resumen: Se presenta el primer registro de Ambidexter symmetricus para la península de Yucatán. Con este registro se extiende la distribución geográfica conocida de esta especie al sureste del golfo de México. En visitas mensuales de mayo a noviembre del año ***2014 a Seybaplaya, Campeche, se recolectaron 13 ejemplares de esta especie; 1 ejemplar macho y el resto hembras ovígeras, lo que muestra*** que esta especie presenta una reproducción continua.

The northern coast of the Mexican state of Yucatán has only been cursorily sampled in the past, with most of this effort concentrated on the largest coral reef in the Gulf of México, Arrecife Alacranes. The present study reports on recent collections (June 2008 - September 2013) of caridean shrimp in Yucatán, including Arrecife Alacranes and other reefs, as well as coastal lagoons and beaches. Additionally, a number of species are reported based on older, unidentified museum material. Six species represent new records for the Gulf of México [Janicea antiguensis (Chace, 1972), Gnathophyllum modestum Hay, 1917, Lysmata jundalini Rhyne, Calado and dos Santos, 2012, Periclimenes sandyi De Grave, 2009, Rapipontonia platalea (Holthuis, 1951a), Typton tortugae, McClendon, 1911], and 11 species are confirmed new records for México [Lysmata ankeri Rhyne and Lin, 2006, L. pederseni Rhyne and Lin, 2006, L. rafa Rhyne and Anker, 2007, Ascidonia miserabilis (Holthuis, 1951b), A. quasipusilla (Chace, 1972), Neopontonides chacei Heard, 1986, Periclimenaeus maxillulidens (Schmitt, 1936), P. pearsei (Schmitt, 1932), P. schmitti Holthuis, 1951b, Typton prionurus Holthuis, 1951b, Processa manningi De Grave and Felder, 2012], adding up to a total of 17 newly reported species for the East coast of México. Further, the colour pattern of several species is documented for the first time.