Feeding appendices studies: the chelae of Aegla uruguayana (Decapoda: Anomura) by geometric morphometrics approach

WILLINER VERONICA; GIRI FEDERICO; COLLINS PABLO AGUSTIN

Congreso; Crustacean Summer Meeting 2013; 2013

The assembly of morphological and ecological information can be a way to approach the understanding of trophic strategies. In decapods the complexity involved in the feeding appendages has played a key role in the successful colonization of different environments showing a wide range of trophic options. The aim of this work is to analyze the shape patterns of the chelae of the freshwater anomuran Aegla uruguayana. The specimens were divided in four ranges according to their sizes (0-5 mm, 5-10 mm, 10-15 mm and 15-20 mm of cephalothorax length), in order to determine different food strategies. Digital pictures of all specimens were taken using a stereomicroscope with digital camera. Ten landmarks were recorded on the inner (palmar) view of the chelae through the tpsDig program. For the posterior analysis the MorphoJ software were used.  Configurations were superimposed through the Generalized Procrustes Analysis. Shape variation in samples was first explored through PCA. The first results showed shape variations pattern between different size classes being the smaller structures more stylized than the chelae of the larger specimens. Particularly, in the pseudocrabs of the larger size the pollex base is more robust than in specimens of smaller sizes.The manus of the bigger pseudocrabs are higher and shorter than the smaller. The obligate tuberculate area is longer in the pseudocrabs of the 10-15 mm and 15-20 mm than the other range size. These results reveal a pattern similar to that found in the analysis of the mandible of this species.