Sexual maturity and ontogenetic shape variations in the freshwater anomuran crab, Aegla uruguayana (Decapoda, Aeglidae)

COLLINS P.; GIRI F.; WILLINER V.

Smithsonian Tropical Research Institute Panama

Congreso; ICIRD 2007 11th International Congress of Invertebrate Reproduction and Development, Panamá 2007; 2007

Smithsonian Tropical Research Institute - International Society of Invertebrate Reproduction and Development

The sexual maturity has a close relation with the shape variations in the freshwater anomuran crabs. Moreover, dorsal and ventral forms of the cephalothorax together with the coxa of fifth pereiopod in males indicated the moment in which the individuals begin the reproductive stepwise into the population. The aim of the work is to show the relationship between cephalothorax and coxa form variations, as an ontogenetic change, with the sexual maturity of the freshwater anomuran, Aegla uruguayana. The dorsal and ventral cephalothorax and coxa of fifth pereiopod of this species were photographed. Using a symmetrization process differents landmarks were obtained to analyze the crab shape. The landmarks were digitized by the tpsDig. The configurations were superimposed through PCA analysis to compare the data. The PCA (1 and 2) data from the consensus configuration and a reaction norm model was constructed evidencing differences among the size forms. We could observe that the dorsal cephalothorax and coxa of fifth pereiopods present difference between juveniles, males and females, and individuals of 12-16 mm CL have shape close to the “consensus configuration” in all population, which is correlated with the begin of sexual maturity in males. Also, we can see size shape differences among juveniles and adult individuals of the population. The differences in shape were observed mainly in the coxa of the fifth pereiopod of males as the lengthen of the sexual tube indicates an ontogenetic shape variation. Moreover the functional maturity occurred simultaneously with cephalothorax and coxa forms variation. These show that the individual potential capacity of A. uruguayana in each reproductive event is different in the active sexual population.