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


  • Aníbal H. Lezcano Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas
  • Rolando González-José Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas
  • Eduardo D. Spivak Universidad Nacional de Mar del Plata
  • Fernando G. Dellatorre Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas - Universidad Nacional de la Patagonia San Juan Bosco



Cyrtograpsus altimanus, allometry, geometric morphometrics, Río de la Plata estuary, Nuevo Gulf, local adaptations, contrasting habitats


Cyrtograpsus genus was traditionally considered to be composed of three species: C. angulatus, C. altimanus and C. affinis. However, recent studies have found solid evidence suggesting that C. affinis and C. altimanus belong to a single species and hypothesize that the morphological differences which caused this misclassification could be related to different ecophenotypes or life stages. Here we report a geometric morphometrics study on the carapace shape of Cyrtograpsus specimens from the Río de la Plata estuary (36°S) and the Nuevo Gulf (42.75°S), testing for shape differences between different sizes (allometry) in the two environments. We found that previous morphological descriptions of the two species were associated with different sizes of a continuous, statistically significant allometric shape variation, concluding that C. affinis is a junior synonym of C. altimanus. We also found significant differences in the carapace shape between estuarine and marine environments, suggesting an effect of the environmental variables on carapace shape and a potential adaptive value of this trait.


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How to Cite

Lezcano AH, González-José R, Spivak ED, Dellatorre FG. Geographic differences in the carapace shape of the crab Cyrtograpsus affinis (Decapoda: Varunidae) and its taxonomic implications. scimar [Internet]. 2012Jun.30 [cited 2023Dec.3];76(2):329-37. Available from:




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