New Insights on the Geographical Distribution of the Malagasy Genus Neogrosphus Lourenço, 1995 (Scorpiones: Buthidae) with the Description of a New Species from a More Humid Environment ^†

Madagascar remains one of the major hotspots of diversity and endemism in the world. Its scorpion fauna provides a striking example, with more than one hundred known species, all endemic, within a territory of only 587,000 km². These species are associated with entirely endemic genera and, to a large extent, endemic familial lineages. While some groups are diverse and locally abundant, others are inconspicuous and occur at very low densities, as is the case for the genus Neogrosphus Lourenço, 1995. In this contribution, the distribution patterns of Neogrosphus are reassessed in light of new material and a revised eco-biogeographical framework. Until recently, this genus comprised three species: Neogrosphus griveaudi (Vachon, 1969), restricted to the dry forest formations in the southern and western portions of Madagascar; Neogrosphus blanci Lourenço, 1996, known from the central region; and Neogrosphus andrafiabe Lourenço, Wilmé & Waeber, 2015, endemic to northern dry formations. A fourth species is described here from mesic forest formations in Andohahela National Park. The current distribution of the genus is shown to be highly fragmented across a broad environmental gradient ranging from subarid to more humid conditions. This pattern is interpreted as the result of historical fragmentation processes linked to limited dispersal capacity and long-term landscape evolution. On this basis, the general framework previously proposed to explain species diversity and vicariance in Malagasy scorpions is revisited and refined.