Visual communication and aggressive behaviour in a giant mute torrent-frog, Megaelosia apuana (Anura; Hylodidae): Supplementary Material

Advertisement call is the most common signal used by anurans for intraspecific communication. However, some species have lost the ability to emit these vocalizations and are denoted as mute. Alternatively, these species may communicate by visual, tactile and chemical signals. The lack of advertisement call could be explained by the high background noise of breeding microhabitats. A model group to study alternative communication tactics is the genus <i>Megaelosia</i>, which is composed by seven mute species that inhabit noisy streams, and for which no information on intraspecific communication is available. We monitored a population of <i>M. apuana</i> and described its visual signalling during aggressive interactions between males. This interaction included visual signalling, physical combat, and the retreat of the smaller individual. No audible sound was detected during the whole aggressive interaction, reinforcing the genus muteness. This is the first report of any communication behaviour for the genus <i>Megaelosia</i>.

广告鸣唱（advertisement call）是无尾类（anurans）用于种内通讯的最常见信号。然而部分物种已丧失发出此类鸣唱的能力，被归类为静音物种。此类静音物种或可通过视觉、触觉与化学信号完成种内通讯。广告鸣唱的缺失，可归因于其繁殖微生境中存在的高强度背景噪音。用于研究替代通讯策略的模式类群为大臂蟾属（*Megaelosia*），该属包含7种栖息于喧闹溪流中的静音物种，目前尚无关于其种内通讯的相关研究资料。本研究对阿普阿纳大臂蟾（*M. apuana*）的一个种群进行了监测，并描述了雄性间攻击互动过程中的视觉信号行为。该互动过程包含视觉信号展示、肢体对抗以及体型较小个体的撤退行为。整个攻击互动全程未检测到可听声响，进一步佐证了该属物种的静音特性。本研究为大臂蟾属（*Megaelosia*）首次报道其通讯行为相关内容。