he present dissertation addresses the study of the diversity, systematics, biogeography and evolutionary history of squat lobster superfamily Galatheoidea, founded on integrative taxonomy criteria. Squat lobsters are a highly diverse group of decapods, and every year dozens of new species are described. Galatheoidea includes the families Galatheidae, Munididae and Munidopsidae (squat lobsters), and Porcellanidae (porcellanid crabs), each characterized by their different external morphology, bathymetric distribution and genetic diversity. They have a rich fossil record since the Upper Jurassic and a current peak of maximum global diversity in the Central Indo- Pacific Ocean. Their high diversity, the presence of both cryptic and morphologically variable species, the poorly understood phylogenetic relationships of many lineages at all taxonomic levels, and ecological differences across families make them a challenging group to tackle evolutionary questions. The general aim was to get closer to squat lobster real diversity through the combined analyses of morphological and molecular characters, species delimitation and type specimen revisions. Once having a better taxonomic knowledge, the objective was to solve phylogenetic relationships at supraspecific levels, unveiling their evolutionary and biogeographic history by describing and comparing diversification patterns in different genera from deep-sea and shallow-water. For these purposes, different genera from both deep and shallow environments were studied: Coralliogalathea, Fennerogalathea, Phylladiorhynchus (Galatheidae), Atlantic Munida species (Munididae), Leiogalathea and Munidopsis (Munidopsidae). Several approaches were employed to accomplish the aims: specimen morphological examination, measures and analyses, multilocus and mitogenomic phylogenetic reconstructions, single and multilocus species delimitation, divergence time estimation, ancestral character reconstruction and mapping for geographic distribution and bathymetric patterns. As a result of these approaches, the present dissertation gathers 65 new species formal descriptions: three of Coralliogalathea, three of Fennerogalathea, three of Munidopsis, 15 of Leiogalathea and 41 of Phylladiorhynchus. Seven synonyms were recovered and one junior synonym proposed. The taxonomic validity and phylogenetic value of morphological characters are discussed, revealing the existence of a high level of homoplasy and the scarcity of synapomorphic characters. Comparison among genetic distances revealed that ranges vary greatly depending on the group. For instance, whereas most Munidopsis species present low genetic interspecific distances, some Phylladiorhynchus species are highly divergent; this might mean that Phylladiorhynchus is constituted by genus-level independent lineages. The evolutionary history reconstruction of Munidopsis revealed that the genus is polyphyletic and constituted by more than 20 ancient lineages characterized by different evolutionary histories and trends. Some of these lineages correspond to old genera currently included in the synonymy of Munidopsis, but others would constitute new genera. These genus-level independent lineages are well differentiated morphologically on the basis of the number of telson plates, the type of rostrum and the presence and position of ocular spines, among other characters. A new phylogenetic hypothesis for Galatheoidea was proposed with mitogenomic data; Porcellanidae was recovered as the earliest offshoot within Galatheoidea, supporting an earlier acquisition of the crab morphology than previously thought. A biogeographic origin in the Tethys Sea during the Upper Oligocene was recovered for Leiogalathea; its current pattern of diversity (low diversity in the Atlantic and high diversity in the Central Indo-Pacific) is explained by Tethyan vicariance and posterior dispersal and high diversification towards the East. Several species of squat lobsters from both shallow and deep-waters share patterns of diversification and centers of diversity but have slight differences likely because the bathymetric ranges might influence their evolutionary history. A pattern from shallow-waters to deep-sea colonization was found for Phylladiorhynchus, which occurred at least twice in the evolutionary history of the genus. The taxonomic effort made along these years has allowed inferring all these evolutionary processes, highlighting taxonomy as an essential part in the study of biodiversity evolution.