| Summary: | Doutoramento em Biologia In the complex and rich Northeast (NE) Atlantic and Macaronesia coasts, the superoder Peracarida (Crustacea) is one of the most abundant and commom marine invertebrate taxa with an important role in benthic communities. The study of this group is often limited to inventory lists or benthic community studies and the genetic knowledge of the group in this region is poor. The main goal of this thesis was to improve knowledge on Peracarida diversity and evolution in the NE Atlantic and Macaronesia, with particular emphasis on shallow water and rocky shore members of the orders Amphipoda, Isopoda and Tanaidacea. The thesis comprises five chapters with original research, entailing a DNA barcodebased screening of the species diversity in this group through the comparison of morphology and molecular-derived data (chapter 2), a set of two studies of the isopod genus Dynamene (chapters 3 and 4), one chapter about the amphipod family Hyalidae (chapter 5), and a multi-species analyses of the diversity and broad phylogeographic patterns of Macaronesian peracarideans (chapter 6). In the first chapter, we reported a DNA barcode reference library for the superorder Peracarida, comprising specimens from marine Atlantic coasts, mainly from Iberian Peninsula, together with additional members of the same or sister taxa from other locations. A higher number of Barcode Index Numbers (BINs) compared with the number of morphospecies was found, with some of them displaying up to six BINs. The presence of deeply divergent intraspecific lineages suggests the existence of considerable overlooked taxonomic diversity, even in one of the most well-known peracaridean faunas in the world. These findings indicate the need for a broad, comprehensive and integrated revision of the peracaridean fauna from the Southern European Atlantic coasts. In the second chapter, the commom but species-poor and controversial isopod Dynamene genus was investigated in detail by examining thousands of specimens records sampled during more ...
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