Nyctimantis brunoi: Predation

Abstract

Nyctimantis brunoi is a hylid endemic to the Atlantic Forest, distributed along the coast of São Paulo, Rio de Janeiro, Espírito Santo, and Bahia states and continental areas of Minas Gerais (Ruas et al. 2013. Check List 9:858–859). This species is known as a casque-headed frog due to its heavily ossified skull bearing cranial crests, ridges, and flanges (Trueb 1970. Univ. Kans. Publ., Mus. Nat. Hist. 18:549–716). This type of skull usually is associated with phragmosis, a protective behavior in which the animal enters a hole and closes it with the head (Jared et al. 2005. J. Zool. 265:1–8). Several studies have focused on its ecological and morphological aspects (e.g., Mesquita et al. 2004. Phyllomedusa 3:51–59; Murta-Fonseca et al. 2020. Cuad. Herpetol. 34:5–15), however, there are no records of predation on N. brunoi. At 0700 h on 27 February 2024, we found a carcass of an adult N. brunoi recently predated in the native plant nursery of the Parque Estadual do Rio Doce, Marliéria Municipality, Minas Gerais, Brazil (19.7625°S, 42.6308°W; WGS 84; 407 m elev.). The carcass had an intact head and vertebral column up to the sacrum. The arms, legs, and all trunk muscles and viscera had been consumed (Fig. 1). The intact head of the N. brunoi carcass caught our attention; possibly the predator avoided consuming this region due to intense ossification or the presence of toxins. This species produces an extremely potent venom in the skin glands of its head, inoculated through bony spines that pierce the skin in areas with glands (Jared et al. 2015. Curr. Biol. 25:2166–2170). Predators typically consume poisonous frogs from the posterior region, avoiding areas with concentrated poison glands (e.g., Bastos and Haddad 1997. Amphibia-Reptilia 18:295–298.; Couto et al. 2024. Herpetol. Notes 17:453–457). In contrast, non-poisonous anurans are often eaten whole by predators (e.g., Ferreira et al. 2017. Herpetol. Notes. 10:111–114; Ceron et al. 2020. Acta Biol. Colomb. 25:359–367). Although the specific predator of the N. brunoi remains unidentified, this is an important record that demonstrates for the first time a predation event on this venomous species.