Horns and Scales: The Hidden Diversity of Furcifer willsii

Furcifer willsii is a remarkable Malagasy chameleon, endemic to the eastern rainforests and known for its relatively stout body and striking cranial appendages. This species inhabits humid forest corridors, where its cryptic coloration and arboreal lifestyle allow it to blend seamlessly into the canopies of the typically inhabited biotopes on the margin of forests along streams and even in gardens and cultivated areas. Despite its relatively broad distribution, population densities vary considerably across localities.

Field observations indicate that the population near Moramanga is significantly smaller than that of the Andasibe area, suggesting ecological or demographic differences between sites. Morphological variation further supports this distinction. Males from Andasibe possess much larger, well‑developed horns, while those from Moramanga exhibit only pointed spikes. Females also show differences in scalation, with body texture and arrangement of tubercles diverging between the two populations.

Such variation raises important taxonomic questions. It is plausible that these populations represent distinct evolutionary lineages, potentially warranting recognition at the subspecific level. Genetic analyses would be essential to clarify whether they are truly conspecific or whether hidden diversity exists within F. willsii. Comparable cases have already been documented in Malagasy chameleons, such as Calumma hofreiteri, C. roaloko, and C. juliae, where subtle morphological differences correspond to distinct taxa.

The evidence suggests that Furcifer willsii may conceal greater diversity than currently recognized, underscoring the need for integrative studies combining morphology, ecology, and genetics.