Integrative taxonomy of interstitial asellote isopods (Crustacea, Isopoda) from the Western Pacific region

Abstract

There have been a very few extensive studies on the interstitial asellote isopods, despite them being a evolutionarily highly successful group which is highlighted by the species geographical distribution in various interstitial habitat from sand beaches, freshwater and also in groundwater. It is, however, essential studying an interstitial asellotes as key elements to understand on the colonization of both deep sea and freshwater water groups. In this respect, the family Lepidocharontiodae, Janiridae and Microcerberidae may provide suitable model to answer such evolutionary and biogeographical questions. For this PhD thesis, selected asellote isopods of the interstitial environment in the Western Pacific region were studied. Taxonomic description of new species, their morphological variation, genetic diversity, and a new systematic rearrangement were mainly discussed. To address this issues, I employed several analytical methods, such as population genetics and new techniques for geometric morphometric analysis, as well as a classical taxonomic observation. As a result, new species of interstitial asellotes including Lepidocharontidae, Janiridae and Mcirocerberidae were described. Moreover, two genetically diverged lineages of Coxicerberus fukudai and its morphological variation could be observed from the populations of East Asia. Finally, the new systematic position of the Microcerberidae were proposed represented by the close relationship with the freshwater asellote, Aselloidea revealed by two nuclear ribosomal DNA.