First report of the parasite crustacean Leidya distorta (Isopoda: Bopyridae) on the fiddler crab Uca spinicarpa (Decapoda: Brachyura) in Yucatán coasts, Mexico

Parasitic isopods, particularly members of the Bopyridae that infest crustacean hosts, have received scant study in many geographic regions. As part of a project aimed at documenting parasites of fish and invertebrates from the coast of Yucatán, Mexico, 2,467 individuals of the fiddler crab Uca spinicarpa were collected from March 2002 to July 2007. Based on the sampled specimens, we report the presence of Leidya distorta in the branchial chamber of U. spinicarpa for the first time. We found a prevalence of 3.77%, mean intensity of 1.47, and mean abundance of 0.06 for this parasite. With the addition of L. distorta, the number of bopyrids reported from Mexican coasts increases to 44 species. Males of U. spinicarpa were more often infested than females, which could be due to the sex ratio being strongly skewed towards males in the host sample studied (0.85:0.15M:F). Morphological differences between males and juveniles, as well as between sub-adult and adult females of L. distorta are described. Los isópodos parásitos, particularmente los Bopyridae que infestan crustáceos, han recibido escasa atención en varias regiones geográficas. Como parte de un programa para documentar parásitos de peces e invertebrados en las costas de Yucatán, México, se recolectaron manualmente 2,467 cangrejos Uca spinicarpa de marzo de 2002 a julio de 2007. Como parte de los resultados, reportamos por primera vez la presencia de Leidya distorta en la cámara branquial de U. spinicarpa. También se presentan los valores de prevalencia (3.77%), intensidad media (1.47) y abundancia media (0.06) para este parásito. Con la adición de L. distorta, el número de bopíridos registrados para las costas mexicanas se incrementa a 44 especies. Los machos de U. spinicarpa resultaron más infestados que las hembras, lo que puede estar asociado a la proporción sexual sesgada a favor de los machos de la población hospedera (0.85:0.15M:H). Se describen algunas variaciones morfológicas de machos y hembras jóvenes, subadultas y adultas de L. distorta.