Unrecognized species diversity and new insights into colour pattern polymorphism within the widespread Malagasy snake Mimophis (Serpentes: Lamprophiidae)

Although many wide-ranging taxa occur in Madagascar, phylogeographic studies for most of these species are still lacking. This is especially the case for snakes, where of more than 100 endemic species, the population structure of only two species has so far been examined. Here, we examine genetic population structure of one of the most common snakes of Madagascar, Mimophis mahfalensis (Grandidier, 1867). This taxon is the only representative of Psammophiinae in Madagascar, where the majority of species in this subfamily is distributed throughout mainland Africa. Applying an integrative approach, where both morphological data and genetic results from coalescent species delimitation analyses are considered, we determine that Mimophis mahfalensis is composed of two distinct taxa: M. mahfalensis in the central montane and southern parts of Madagascar, and a second new species restricted to the north and north-west, which we describe here. We also examine the colour pattern polymorphism exhibited in Mimophis, which has been previously hypothesized as sexually dimorphic and/or geographically correlated. However, we find all three colour morphs in both sexes, and both species of Mimophis. Our work highlights the importance of phylogeographic studies that examine wide-ranging taxa to detect cryptic species diversity, even amongst species that are common, or have been previously considered to be well known.

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