Acoustic repertory of the “Colostethus” ruthveni group (Anura: Dendrobatidae) and comments on the distribution

The “Colostethus” ruthveni group represents an endemic dendrobatid lineage in the Sierra Nevada de Santa Marta (SNSM), an isolated massif in northeastern Colombia. This group has a complex taxonomic history and comprises the nominal species, from the northern and northwestern sector of the SNSM and an undescribed morph provisionally named as “Colostethus” sp. ruthveni-like, from the southeastern sector of this mountain massif. Herein, we describe the advertisement calls of members of the “C.” ruthveni group from several basins in the northern, northwestern, and southeastern sectors of the SNSM, and their geographic variation. In addition, we describe the courtship calls of the northwestern populations and provide comments on the distribution of the members of the group. The advertisement call of the “C.” ruthveni group consists of a trill with a long series of notes. All advertisement call traits show statistical differences among the assessed basins. The principal component analysis revealed overlap in call traits of individuals from the northwestern sector of the SNSM (“C.” ruthveni sensu stricto), while the populations of the southeastern sector (“C.” sp. ruthveni-like) and northern sector (“C.” cf. ruthveni) varied from these calls with respect to the dominant frequency and rate of notes per second, respectively. Acoustic divergence of advertisement calls of “C.” ruthveni sensu stricto and “C.” sp ruthveni-like is congruent with morphological and molecular evidence. Courtship call of “C.” ruthveni sensu stricto is a short partially fused pulsed squeak, followed by the usual advertisement call. This courtship call differs drastically in structure from the advertisement call, showing once again the complexity of the acoustic repertory of dendrobatoid frogs.