Taxonomy, Phylogeography AND Myrmecophily of the Spider Genus Mastigusa (Araneae, Cybaeidae

The spider genus Mastigusa Menge, 1854 includes small (3 - 4.4 mm) entelegyne spiders represented by extant as well as fossil species that present characteristic features in the male and female genitalia. The genus has a palearctic distribution being present in Europe, North Africa, and the Near East, and shows ecological plasticity, with free-living, cave-dwelling and myrmecophile populations known. The taxonomic history of the genus has been problematic, both regarding its phylogenetic placement and the number and delimitation of the species it includes. Three extant species are currently recognized: M. arietina (Thorell, 1871), M. lucifuga (Simon, 1898) and M. macrophthalma (Kulczyński, 1897), but the characters used to discriminate them have been inconsistent, leading to confusion about their identification and distribution. In the present thesis we addressed the taxonomic issues regarding Mastigusa by combining molecular and morphological data in an integrative taxonomy approach. For the first time, we included the genus in a molecular phylogenetic matrix solving a long going debate regarding its familiar placement, obtaining a well-supported placement in the family Cybaeidae, in a sister group relationship with the genus Cryphoeca Thorell, 1870. We used multi-locus molecular phylogenetic and DNA barcoding techniques as a starting point for identifying divergent lineages within the genus and revise the taxonomic status of the known Mastigusa species, identifying a new species from the Iberian Peninsula, Algeria and the United Kingdom, M. raimondi sp. n. This taxonomic revision allowed a phylogeographic and ecological study of Mastigusa within its distribution range, carried out using molecular phylogenetics and ecological niche modelling techniques, aiming at a comparison of the lifestyles and ecological requirements of the different species on a geographic scale. The Italian Alps were finally used as a testing ground for investigating the ecology and host pref