The genus Pseudopaludicola Miranda-Ribeiro, 1926 belongs to the family Leptodactylidae, subfamily Leiuperinae (Pyron and Wiens, 2011), and includes 21 species endemic to the Neotropics (Frost, 2016). Pseudopaludicola mystacalis (Cope, 1887) is a small- sized frog (maximum snout–vent length 16.3 mm in females) widely distributed throughout South America (Pansonato et al., 2014; Frost, 2016). However, some populations across the distribution range show distinct karyotypes, morphology, and vocalizations, suggesting the presence of a species complex (Fávero et al., 2011; Pansonato et al., 2013). Individuals of P. mystacalis typically show crepuscular activity, and males call from small swamps formed by headwaters and flowing rainwater, with creeping vegetation composed by grasses (Santana and Tostes, 2007). In addition, habitat use patterns by P. mystacalis are affected by grazing management and cattle (Pelinson et al., 2016). However, studies about diet and predator-prey interactions of this species are still absent. On 27 October 2016 at 21:00 h, we observed a male individual of P. mystacalis preying on an ant of the genus Tranopelta Mayr, 1866 (family Formicidae, subfamily Myrmicinae; Fig. 1). The event occurred in an artificial pond located in the rural area of Acreúna Municipality, Goiás State, Central Brazil (17.3617° S, 50.1650° W). Observations of predator-prey interactions improve our understanding of relationships among taxa. Additionally, this basic information allows ecological inferences about community structure, resource use, and spatial distribution (Toft, 1985), as well as evolutionary Herpetology Notes, volume 10: 477-478 (2017) (published online on 13 September 2017) First report of predation by Pseudopaludicola mystacalis (Anura, Leptodactylidae) Pedro de Oliveira Calixto 1, * and Lucas Batista Crivellari 2 1 Programa de Pós-Graduação em Zoologia, Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Paraná 80060-000, Brazil 2 Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Paraná 80060-000, Brazil * Corresponding author e-mail: pocalixto@gmail.com Figure 1. Male Pseudopaludicola mystacalis preying on an ant (Tranopelta sp.). (A) The moment before predation, with the frog eyeing the ant. (B) The moment of predation, with only the tip of the ant’s wing (arrow) still protruding from the frog’s mouth. (C) A specimen of the predated ant, genus Tranopelta. Scale bar = 20 mm. Photos by Pedro de O. Calixto.