Sexual dimorphism of gnathopods 1 and 2 and uropod 3’ shapes in Parhyale darvishi (Momtazi and Maghsoudlou, 2016) based on geometric morphometric methods

Sexual dimorphism of gnathopods 1 and 2 and uropod 3’ shapes in Parhyale darvishi (Momtazi and Maghsoudlou, 2016) were investigated by geometric morphometrics. A total 50 males and 50 females were experimented. Anatomical aspects of gnathopods and uropods were photographed and cartesian coordinate (semilandmarks of organs' margin) aligned by semilandmark sliding based on minimum bending energy. Statistical significance of sexual dimorphism was tested by multivariate analysis of variances; linear discriminant analysis and clustering analysis (ward method). Multivariate regression analysis based on partial warps and uniform components was used to depicting shape variations related to sex [1]in studied anatomical parts in the form of deformation frames. The results show all three anatomical parts was significantly different shape in male and females (F>17.15, p < 0.0001). The deformation regression frameworks of first gnathopod show that the ratio of length to width in females are less than males. The second gnathopod has an oval shape in females instead of circular form in males. The shape of third uropod in males is more extended and bearing subacute angles. Based on present studies, the accurate description of sexual dimorphism specially in taxonomic characters provide ability for identification based on females and detail study of species.