Brazilian torrent frogs may use sophisticated audio and visual signals to communicate, including inflating vocal sacs, squealing, and arm waving, according to a study published January 13, 2016 in the open-access journal PLOS ONE by Fábio P. de Sá, Universidade Estadual Paulista, Brazil, and colleagues. Frog communication plays a role in species recognition and recognition of potential rivals or mates. The authors of this study investigated communication in the Brazilian torrent frog, an endemic frog to Brazil a frog endemic to Brazil, where males are known to be territorial and display elaborate courtship behavior. The researchers observed nearly 70 male and female torrent frogs over a period of 15 months. 

The researchers observed a complex repertoire of acoustic and visual displays during advertisement, including long-range, short-range, and courtship communication with other frogs. During courtship, the authors observed males performing visual displays using their toes, feet, hands, legs, arms, vocal sacs, head, and body while females only displayed hand, arm, and body movements. They also describe a behavior previously unknown in frogs, where females use a combination of visual displays and touch to stimulate the male's courtship call. They also found that frogs may choose to signal with their left or right limbs, and that males can choose which of their two vocal sacs to use for visual signaling. Torrent frogs also exhibit a diverse acoustic repertoire that, besides the advertisement call, include peeps, squeals, and courtship calls. 

The authors suggest their results indicate that Brazilian torrent frogs have one of the most diverse repertoires of visual and audio displays known to frogs, indicating that communication in torrent frog species is likely more sophisticated than previously thought. 

Dr. Fábio P. de Sá adds "Our study indicates that communication in species of the genus Hylodes is more sophisticated than expected. Also we suggest that communication in frogs is more complex than thought. Likely, that is particularly true for tropical areas, where there is a higher number of species and phylogenetic groups and/or where there is higher microhabitat diversity."