Geographic differences in the carapace shape of the crab Cyrtograpsus affinis (Decapoda, Varunidae) and its taxonomic implications

LEZCANO, ANIBAL; GONZÁLES-JOSÉ, R.; SPIVAK, E.; DELLATORRE, F. G.

SCIENTIA MARINA

INST CIENCIAS MAR BARCELONA

Año: 2011 p. 1 - 29

0214-8358

El presente trabajo fue realizado en el marco de la tesis de grado del primer autor. Mi rol en el mismo es protagónico tanto en la concepción de las hipótesis, como en la dirección de la tesis y en la escritura del artículo. Cyrtograpsus genus was traditionally considered as composed of three species: C. angulatus, C. altimanus and C. affinis. Recent works found solid evidence suggesting that C. affinis and C. altimanus belong to a single species and hypothesize that morphological differences which caused this misclassification, could be related to different ecophenotypes or life stages. Here we report a geometric morphometrics study on carapace shape of Cyrtograpsus specimens from Río de la Plata estuary (36ºS) and Nuevo gulf (42.75ºS), testing for shape differences between different sizes (allometry) and both environments. We found a statistically significant allometric shape variation and also that previous morphological descriptions of both species were associated to different sizes of a continuous allometric trajectory, concluding that C. affinis is a junior synonym of C. altimanus. Also we found significant differences in the carapace shape between different environments (estuarine vs marine), suggesting an effect of the environmental variables on carapace shape, and a potential adaptive value of this trait.