Carné, A., D. R. Vieites, X. Ferrer, M. Moreno, G. Ponz-Segrelles, N. A. A. Rahagalala, S. E. Rakotomanga, A. Ramón- Laca, F. M. Ratsoavina & M. P. van den Burg

Microendemism in Madagascar: small ranges or sampling gaps? The case of the frog Wakea madinika. pp. 160-170.

Abstract. Madagascar is one of the most biodiverse regions on Earth, with exceptionally high amphibian species richness and endemism, though increasingly threatened. Over recent decades, amphibian research efforts have intensified; however, many species remain documented from one or few localities, leading to the hypothesis that they may be micro-endemics. Among these is Wakea madinika, a Data Deficient mantellid frog species described in 2002 and reported only once from a single cacao plantation in the Sambirano region. We provide novel genetic and distribution data from newly discovered populations, analyse its potential distribution range, and revise its conservation status. Our findings reveal populations within the Sambirano River valley and beyond, significantly expanding its range from one to five localities, covering a minimum convex polygon of 1600 km² in northwestern Madagascar. Distribution models identified the Sambirano basin as highly suitable for the presence of the species, with additional potential habitats extending northward and southward, highlighting areas that may host undiscovered populations. The discovery of populations in unexpected localities, including Réserve Spéciale d’Ankarana and Sorobe, challenges its previous micro-endemic classification and confirms the species’ presence south of the Sambirano River and much further north. Genetic data revealed unexpectedly low intraspecific divergence (0.66%) considering the geographical range and small body size, suggesting population level dispersal greater than previously thought. Populations on both sides of the Sambirano River shared identical mitochondrial sequences, indicating recent gene flow. This suggests that the river, long considered a barrier, may not have recently hindered gene flow as previously thought. Except for Ankarana, the species is only known from cacao plantations, suggesting it may be a forest dweller persisting in suboptimal habitats. We recommend reclassifying W. madinika as Endangered on the IUCN Red List based on our findings. Our study challenges the generalization of micro-endemism and underscores the importance of exploring Madagascar’s lesser-sampled secondary habitats to understand species distributions better, address the Walla­cean shortfall, and inform conservation strategies.

Key words. Amphibia, Anura, Mantellidae, Wallacean shortfall, micro-endemism, distributions, conservation, Madagascar.