Previous studies found that two larvae of the family Ceratophryidae, Ceratophrys ornata (Ornate Horned Frogs) and Ceratophrys cranwelli (Cranwell's Horned Frogs), are able to produce underwater sounds as an antipredator strategy. Here, we determined whether tadpoles of another ceratophryid, Lepidobatrachus llanensis (Llanos Frogs), also produce underwater sounds in similar contexts of intraspecific interactions. Moreover, to compare the mechanism displayed by Ceratophrys spp. with related species, we tested the existence of an antipredator mechanism (= behavior) in L. llanensis tadpoles that diminishes the frequency of predation between conspecifics in the presence of heterospecific prey. Lepidobatrachus llanensis tadpoles exhibited an antipredator mechanism that is displayed on intraspecific interactions. Extensive trials failed to reveal sound production (in the 20 hertz [Hz]–20 kilohertz [kHz] range) in L. llanensis, contrasting our observations on Ceratophrys spp. Nevertheless, L. llanensis tadpoles recognized conspecifics because they consistently avoided each other. Under the experimental conditions described, we found L. llanensis tadpoles first eat all heterospecific prey and only then switch to cannibalism. Tadpoles began eating conspecifics only when prey were scarce and after a period of hunger. Moreover, cannibalistic events increased at higher predator-prey proportions. When comparing the number of events of cannibalism recorded for L. llanensis and the related C. cranwelli, under the same experimental conditions, we concluded that L. llanensis cannibalize 1.5 times more often. The genus Lepidobatrachus has distinctive and unique morphological characters that are divergent from its relatives (Ceratophrys, Chacophrys). The antipredator mechanism in L. llanensis contrasts those of Ceratophrys spp. and may be yet another differing characteristic of this group.