First morphological description of the Galápagos pink iguana (Conolophus marthae) hatchling: a critical step for its conservation

The Galapagos pink iguana (Conolophus marthae) is endemic to Wolf Volcano on Isabela Island in the Galapagos archipelago. Due to its remote and hard-to-access habitat, the recently discovered and critically small wild population of the pink iguana has been extremely challenging to study. Herein we provide a first description of the morphology and behavior of six C. marthae hatchlings, and compare them with 12 hatchlings of the sympatric C. subcristatus. Morphometric measurements (snout–vent length = 10.9 ± 1.63 (SD) cm, tail length = 17.9 ± 3.05 cm, and weight = 47.8 ± 25.4 g) revealed a longer tail relative to its body size (ratio = 1.65 ± 0.23) compared to the sympatric Galápagos land iguana (C. subcristatus) hatchling of similar size (ratio = 1.42 ± 0.11). C. marthae hatchlings also displayed distinctive coloration with a bright green dorsal background with irregular black maculations and a pale, nearly unpigmented ventral surface. A comparative photograph of a subadult C. marthae revealed a directional, ontogenetic color shift: green dorsal areas became black while black maculations gave rise to pink patches, possibly a retained ancestral trait with implications for camouflage or signaling. These findings fill a knowledge gap in the early ecology of Galápagos pink iguana, providing information useful for monitoring recruitment in this Critically Endangered species.