The tadpoles of the Iron Quadrangle, Southeastern Brazil: an update with characterizations of four Scinax Wagler, 1830 (Anura, Hylidae) species

The Iron Quadrangle (IQ) is a critically endangered hotspot for anuran biodiversity, threatened by mining operations and urban sprawl. These activities severely disrupt the natural habitats of these species, leading to habitat loss, pollution, and fragmentation, all of which jeopardize the survival of various anuran populations in the region. To mitigate the impact, it is essential to continuously enhance and update knowledge of the local fauna to support species identification processes required for environmental licensing, conservation policies, and management. This study enhances the knowledge of Scinax larvae from the IQ by characterizing two species, a lineage of the paraphyletic S. auratus, and one Unconfirmed Candidate Species (UCS), with confirmed molecular identification. Of the four characterizations, three are novel, and the geographic range of two species has been significantly extended. We compared the described species with other Scinax from IQ, noting that while one species is easily identifiable, the others are morphologically indistinguishable due to shared polymorphic traits. However, certain characters, particularly in extreme character states, can still aid in identification. This underscores the importance of studies that account for overlapping traits and the integration of molecular tools, especially when morphology alone is insufficient to resolve species identities.