Name: Pizzigalli C

Biodeserts supervisors: JC Brito; F Martínez-Freiría; G Velo-Antón

Title: Phylogeography and systematics of the Mesalina olivieri species complex (Squamata: Lacertidae) from North-West Africa

Institution: University of Porto, Portugal

Status: Completed



Mesalina is a genus of small xeric lizards currently comprising 19 species distributed from West Africa throughout the Saharo-Sindian deserts to the Indo-Iranian plateau. Previous phylogenetic studies highlighted the presence of cryptic diversity within the genus and described new Mesalina species from its eastern lineages. In this study, we investigated the taxonomy and systematics within the Mesalina olivieri species complex, focusing on the Atlantic Sahara (from Morocco to Mauritania). The species complex is currently represented by three recognised species, all of them present in this region: M. olivieri, M. pasteuri and M. simoni. Using an integrative taxonomy approach based on morphological (pholidotic, coloration and pattern) and molecular (one mtDNA and four nuDNA markers) datasets, robust evidence for the existence of additional taxa within the M. olivieri complex is provided, including an undescribed species in Mauritania. Mesalina sp. nov. Moreover, the taxonomical paraphyly of M. olivieri was resolved. All M. olivieri that cluster together with M. simoni were proposed to be included as subspecies of the latter (M. simoni ssp. nov.). The clade including Mesalina sp. nov. and M. simoni diverged from M. olivieri and M. pasteuri around 9.5 Mya whereas these two later species separated 1 or 2 Mya later in the end of the Miocene. The combined analyses supported a new classification of the Mesalina olivieri species complex into four extant species. The new species is sympatric with M. pasteuri in Mauritania but is phylogenetically and morphologically divergent from it. Species distribution modelling suggests that the new taxon occurs exclusively in the rocky areas of the Adrar Atar plateau and neighbouring regions. The relatively wide but fragmented distribution of Mesalina sp. nov. suggests that its conservation status is Least Concern (LC).