Leptodactylus mystaceus

(Fig. 8 C) The species-pair Leptodactylus mystaceus (Spix, 1824) and Leptodactylus didymus Heyer, García-Lopez, & Cardoso, 1996 is totally cryptic with regard to external morphology, only being phenotypically distinguished by advertisement calls (pulsed in L. mystaceus and nonpulsed in L. didymus) (Heyer et al., 1996). Leptodactylus didymus is known to occur at southwestern Amazonia, with punctual records at the lower Juruá River region (Heyer et al., 1996), while L. mystaceus is more widely distributed in Amazonia (Heyer et al., 1996; Silva et al., 2020). However, the widest knowledge gap on the distribution of this species pair is spatially congruent to where they are potentially sympatric, including our study area (Heyer et al., 1996; Silva et al., 2020). As external morphology was the only available information for the assignment of taxonomic status in this case, we opt to be conservative until acoustic vouchers are obtained in the focal area.