Underground cryptic speciation within the Maghreb: Multilocus phylogeography sheds light on the diversification of the checkerboard worm lizard Trogonophis wiegmanni.

Biogeographic and evolutionary patterns in the North African portion of the Western Palaearctic are poorly known. A high fraction of undescribed diversity is expected in this region, especially in groups such as reptiles. Here we used mitochondrial (12S, 16S, cytb) and nuclear (pomc, rag2, cmos) markers and morphological data to investigate phyletic diversification and phylogeographical structure in the amphisbaenian Trogonophis wiegmanni endemic to the Maghreb. Phylogenetic and molecular dating analyses based on gene trees and species trees support three deeply divergent lineages of Pliocene origin, two in Morocco and one in central Algeria and Tunisia. Parapatry, reciprocal monophyly, high genetic divergence and limited morphological differentiation between them suggest that these lineages represent independent cryptic taxonomic units. Emerging lines of evidence from this study and from available literature on Maghreb taxa support (i) a major biogeographic break between western and eastern Maghreb and (ii) a role of the Atlas as a biogeographic divide within the western Maghreb (Morocco). The origin of these biogeographic units is probably associated with the evolutionary events prompted by the Late Miocene palaeogeographic setting and later by Plio-Pleistocene climatic changes and their interplay with prominent orographic barriers within North Africa.