Aplastodiscus musicus is a rare species and the only member of its genus that has not been included in previous phylogenetic studies. This species is known only from its type locality at Serra dos Órgãos National Park in southeastern Brazil, and has not been seen in over 21 yr. Here, we report the re-encounter of an individual of A. musicus at its type locality, describe its advertisement call for the first time, and present a hypothesis concerning its phylogenetic placement. The call of A. musicus is very simple and melodic, composed of one unpulsed note, and emitted at a high repetition rate. It differs from the call of all species of Aplastodiscus and is more similar to those of the A. albofrenatus group. The phylogenetic analysis, based on nuclear and mitochondrial data from all species of Aplastodiscus, recovered A. musicus as the sister taxon of all species currently assigned to the A. albofrenatus group with high support. Our results strongly support the reassignment of A. musicus to the A. albofrenatus group. Previous discussions regarding the evolution of the pericloacal morphology and chromosome number are also revised on the basis of the phylogenetic placement of A. musicus. The re-encounter of A. musicus highlights the importance of increased efforts to search for lost species, especially with the aid of bioacoustics, which permits individual detection and identification at great distances.