ONTOGENY OF THE MANDIBLE OF Aegla uruguayana (DECAPODA, ANOMURA): A GEOMETRIC MORPHOMETRIC APPROACHES

WILLINER V.; GIRI F.; COLLINS P.

PALEONTOLOGIA I EVOLUCIÓ

Institut Catala de Paleontolgia

Lugar: Barcelona; Año: 2009 vol. mem p. 117 - 118

0211-609X

Within the field of study of the morphology of the crustaceans, Garm & Hoeg (2000) state that one of the most interesting lines of research because of its complexity, is addressed by the analysis of the mouthparts. According to other authors (Cartes, 1993), this complexity has played a fundamental role in the colonization success of this group, showing a remarkable range of food options. Aegla uruguayana is a freshwater anomuran crab that lives in lotic and lenitic freshwater environments of the southern state of Río Grande do Sul in Brazil, and in Uruguay and central and northwest Argentina (Bond-Buckup & Buckup, 1994). This decapod belongs to the unique family of anomurans that colonized freshwater environments (Schmitt, 1942). The aim of this work is to analyze the patterns of the mandible of A. uruguayana on specimens of various sizes to determine if juveniles and adults may have different food options. Digital pictures of all specimens were taken using a Moticam 1000 digital microscope camera. Seven landmarks and three semi-landmarks were recorded on the dorsal view of the cephalothorax through the tpsDig program (Rohlf, 2004). Configurations were superimposed through the Generalized Procrustes Analysis (Rohlf & Slice, 1999) in the tpsRelw program (Rohlf, 2005). Shape variation between samples was first explored through Relative Warp analysis. The mandible shape differed among dietary classes (juveniles, sub-adults and adults). The RW 1 showed that the smooth molar process was the dominant deformations. Moreover the RW2 reflected shape variation in the mandible according to molt cycle stage. The MANCOVA reveled significant differences (P