Sexual Dimorphism in the buccal cavity of paternal mouthbrooding cardinalfishes (Pisces: Apogonidae)

The mechanical basis of mouthbrooding in the coral reef cardinalfish (family Apogonidae) has yet to be established. Sexual dimorphism in the anatomy of the oral jaws and buccal cavity of seven species of paternal mouthbrooding apogonids was therefore investigated. A novel silicon injecting technique was used to quantify between sexes differences in size and shape of the buccal cavity. Osteological and morphological measurements were also examined to identify the structural features associated with variation in buccal volumes. Males buccal volumes were proportionally larger by 20–42% in five of the seven species (P