Integrative taxonomy of Madagascar’s sand-swimming skinks (Scincidae: Voeltzkowia, Grandidierina) and preliminary evidence for an overlooked inland belt of white sand patches across the island’s west

Malagasy sand-swimming skinks represent several highly specialized and previously underexplored clades within the monophyletic radiation of scincine lizards of this island. rough comprehensive phylogenomic analyses including newly collected samples, we clarify the evolutionary relationships among these taxa, delimit species boundaries, and formally describe two new species: Voeltzkowia volontany sp. nov. and Voeltzkowia shaihulud sp. nov. Our ndings on the genus Voeltzkowia and the equally specialized sand-swimmer genus Grandidierina suggest that species diversity within these psammophilous skinks is underestimated and shaped by a high degree of allopatry. Intriguingly, this unexpected diversity is geographically structured along a newly identied landscape feature, for which we herein coin the name ‘White Sand Belt’. It consists of an aligned series of discrete, isolated white sand patches spanning >1500 km along western Madagascar. e White Sand Belt appears to follow the contours of the western sedimentary basins of the island, and we propose the hypothesis that it represents a key environmental factor in the diversi cation and distribution of Malagasy sand-swimming skinks and, possibly, other psammophilous organisms.