SEXUAL DIMORPHISM AND MORPHOLOGICAL VARIABILITY OF ROSY BARB PETHIA CONCHONIUS IN TWO RIVER

Abstract

Sexual dimorphism and body shape variations were examined by using Geometric morphometric method, between sexes of Pethia conchonius. A total of 400 (200 male and 200 female) individuals of this species were collected from the Atrai River (Stations: BG, Birganj and KB, Kornai Bazar) and Dhepa Rivers (KS, Khansama and MP, Mohanpur) in Dinajpur district of Bangladesh. From each station 100 fishes (50 male and 50 female) were collected to assess the body shape extracted by recording 11 landmark points on two dimensional pictures of specimens. Sexual dimorphism was found through MANOVA and ANOSIM analyses in PAST software. The findings of the discriminate function analysis showed substantial variance between body shape of the sexes where female exhibited wider abdomen and larger pectoral fins than male. Male had reddish and darker pectoral, pelvic, dorsal anal and caudal fin compare to female. All statistical values i.e. MANOVA, ANOSIM, Discriminant Function Analysis (DFA), PCA and warp score assessment exhibited that significant variations between body shapes of sexes where female possessed a larger body, broader abdomen compare to male. Canonical Variate Analysis (CVA) also showed that male and female of P. conchonius showed sexual dimorphisms. Where, both sexes from the Atrai River were statistically discriminated from the Dhepa River indicating a good source of brood of this species. However, male from one river and female from another river may be used as brood fishes in order to increase quality population of this species.