Estudo filogenético de representantes da subclasse Peritrichia Stein, 1859 (Alveolata: Ciliophora) com base em sequências de 18s-rDNA e caracterização multidisciplinar de Rhabdostyla inclinans Kent, 1881 (Peritrichia, Epistylididae)

Abstract

This work extends the knowledge of the phylogeny of ciliated micro-eukaryote (Alveolata, Ciliophora) of Peritrichia Stein, 1859 subclass based on analysis of 18S-rDNA sequences and compares traditional systematics of the group to the phylogeny based on molecular data. The proposal also presents a multidisciplinary characterization of Rhabdostyla inclinans (Peritrichia, Epistylididae) with morphological, ecological and molecular data. The dissertation is divided into two chapters (sections). In Chapter one (section 1) a phylogenetic study of representatives of Peritrichia subclass was performed with inclusion of 12 new sequences of 18S-rDNA (11 species and four genera - Epistylis, Opercularia, Orborhabdostyla, Rhabdostyla) obtained from organisms collected in ecosystems in the Southeast region Brazil, more precisely in the state of Minas Gerais. In this chapter was discussed the validity of some families of peritrichs and investigated whether the main morphological characteristics used to define the systematics of the group reflect genuine evolutionary divergence. The main contributions of this study were: 1Peritrichia subclass is divided in two major clades; 2Operculariidae family seems to be a natural group; 3There are representatives of the Epistylididae family grouping in different branches of the subclass Peritrichia. This fact suggests that Epistylididae family is a grade and not a natural clade and therefore requires systematic review. ; 4The Rhabdostyla and Orborhabdostyla epistilids did not grouped in the same clade as set out in the current system based on morphological similarities; 5Zoothamniidae family is paraphyletic; 6vorticelids did not formed a natural group requiring major review of the main morphological features currently used as morphological synapomorphies. In chapter two (section 2) was performed a multidisciplinary characterization of epibionts population of Rhabdostyla inclinans on Aeolosomatidae collected in bromeliad tanks in Brazil. This study discusses for the first time phylogenetic placement of the Rhabdostyla genus within peritrich subclass and presents detailed morphology data for this population. Data about information of Epibiotic relationship are presented too. The two 18S-rDNA sequences of Rhabdostyla inclinans obtained clustered with representatives of Vorticellidae family, which refutes the traditional classification of this genus as a epistilid (Epistylididae) based on morphological characters. The molecular results highlight the need to expand the number of sequences of Rhabdostyla genus in genetic databases to better understand the phylogeny of epistilids peritrichs and instigate review and search for new morphological characters to be used as synapomorphy of clades that constitute Peritrichia subclass.