Taxonomy and morphologic phylogeny of Elpidium Müller, 1880 (Crustacea, Ostracoda)

• Ano de defesa: 2017
• Autor(a) principal: Pereira, Julia da Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Diversidade; Diversity; Elpidium; Evolutionary History; Fitotelmata; História Evolutiva; Ostracoda; Phytotelmata; Taxonomia; Taxonomy
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/41/41133/tde-12122017-162201/

Ostracods are microcrustaceans distinguished by some very particular characteristics. They have a great diversity, occupy different environments - freshwater, marine or semi-terrestrial -, can be adapted to challenging environments as temporary or very restricted water bodies and have an extensive fossil record. All these traits make these animals great models to a variety of biological studies such as ecological, evolutionary or paleoenvironmental ones, just to name a few. In spite of this, studies with the group are not as representative when compared with other crustacean groups. When one dedicates its attention to ostracods living in small, restricted and temporary water bodies, this negligence becomes even more evident. One example of it are the ostracods that inhabit environments such as bamboos, tree holes or bromeliads - together called pythotelmata - and of which we know very little. Actually, solely 14 ostracods are known for phytotelmata from the whole world. From these, eight belong to Elpidium, a genus described in 1880 by Fritz Müller and that is still incredibly poorly understood due to the inconstancy on studies involving the genus. In recent years, however, an effort has been made to fill this gap and improve our knowledge about the genus. In this sense, studies are being made in order to have a clear panorama of what it is the real Elpidium diversity and also to go beyond and think in evolutionary and pluridisciplinary terms. In this work, we aim to continue this effort in understanding this neglected group. To that we planned a broad and pluridisciplinary work that could integrate different aspects of our genus of interest. We dedicate then to (1) ontogeny - clarifying poorly comprehended and/or misunderstood ontogenetic aspects of the type species Elpidium bromeliarum; (2) taxonomy - describing four new species and re-describing Elpidium laesslei; and (3) evolutionary history - proposing the first phylogenetic reconstruction for the genus. Ontogenetic developmental aspects of E. bromeliarum are discussed in chapter 1. In it, we analyzed the possibility - previously proposed on the literature - of an additional moult after the adult stage for this species. Such possibility was not corroborated: the species development is not an exception to the nine developmental stages of the three most important freshwater ostracods superfamilies and it is also in conformity with the well-established fact that ostracods do not moult after mature stage. Taxonomy and diversity are studied in chapters 2 and 3. Such chapters are dedicated to the descriptions of four new species - three from Jamaica and one from Rio de Janeiro, Brazil - and the re-description of E. laesslei from Jamaica. Beyond it, these chapters also discuss about the hypothesis of high degree of diversity and endemism for the genus due to allopatric speciation favored by the relative bromeliad isolation. Chapter 3 is also dedicated to the genus evolutionary history, presenting a hypothesis to the evolutionary relationships between its species. Such phylogenetic reconstruction puts Elpidium as a monophyletic group and its species divided into two major clades. Finally, the need of a pluridisciplinary study to the complete comprehension of the genus and our expectations are discussed