Sexual dimorphism of the Weberian apparatus and pectoral girdle in Sundadanio axelrodi (Ostariophysi: Cyprinidae)

The miniature cyprinid fish, Sundadanio axelrodi, exhibits extreme sexual dimorphism in the skeleton of the Weberian apparatus, the fifth rib and pectoral girdle. Musculature associated with the fifth rib and Weberian apparatus also shows a high degree of sexual dimorphism. It is suggested that these modi. cations are responsible for the production of a croaking sound that seems to be restricted to males of the species, based on the lack of any corresponding anatomical specializations in females. (C) 2007 The Authors.