Extreme dermal hypopigmentation and full-body transparency in a leaf-litter fraugastor frog from a lowland tropical wet forest in Costa Rica

Pigment abnormalities in amphibians are rare, particularly those involving the complete absence of all chromatophore
types. We report an exceptional case of extreme dermal hypopigmentation in a presumed juvenile Craugastor fitzingeri observed
in the lowland rainforest leaf litter of Tirimbina Biological Reserve, Costa Rica. The specimen lacked all external pigmentation,
exhibiting complete body transparency with visible internal organs, blood vessels, and unpigmented eyes. This condition likely
represents a combination of congenital albinism and a severe chromatophore deficiency, including melanophores, xanthophores,
and iridophores. Such extreme phenotypes are virtually undocumented in wild, direct-developing amphibians, particularly within
the Terrarana clade. Our finding contributes to the scarce but growing body of literature on congenital pigment anomalies in
amphibians and highlights the importance of continued monitoring and genetic investigation of rare phenotypes in tropical forest
ecosystems.