O gênero cladophora (chlorophyta) no litoral do brasil: estudos morfotaxonômico e molecular

Abstract

The Cladophora genus is one of the most common genera of green algae, widely distributed, occurring from the tropics to the Arctic, has mainly marine habitat, with representatives still occurring in estuaries, brackish and freshwater. Presents morphology easily recognized within the Chlorophyta for possessing stem filamentous uniseriate, branched, formed by giant cells with numerous willing discoid chloroplasts form a parietal reticulum, with bilenticular pyrenoid. Although gender is easily recognizable among the marine green algae, is the one with the greatest difficulties for identification, reflecting the great phenotypic plasticity that has, since the morphology of the stem may vary with age, degree of movement of water, among other habitat features. In addition, the lack of complete and uniform descriptions have contributed to the confusion surrounding the taxonomy of the genus. For better understanding of the relationships between species of Cladophora many molecular phylogenetic studies have been developed, such as the proposition and taxonomic identification of new species, genera and families and intergeneric and intraspecific phylogenetic relationships. However, these are still scarce for tropical regions. On the coast of Brazil the only work that involves the study of DNA data (SSU rDNA) was developed in order to elucidate the molecular phylogenetic relationships of isolates of C. vagabunda occurring along the Brazilian coast. This work was the need to extend this study to other species in Brazil using other molecular markers allied to morphological study of these species. Therefore, there was the taxonomy of species of Cladophora in Brazil based on partial sequences of LSU rDNA, in which 49 were generated sequences. Molecular phylogenetic analysis revealed 17 taxa distributed in two genera: Cladophora (14) and Willeella (3). In Cladophora 14 taxa had their phylogenetic position elucidated, among the four species of Cladophora undetermined, Cladophora sp. 1 has been described as a new species Cladophora codii based on morphological and molecular data, Cladophora sp. 2, Cladophora sp. 3 and Cladophora sp. 4 were separated only in the molecular phylogeny to be described later. The Willeella genus was reestablished by molecular phylogenetic position C. ordinata in a clade separate from other species Cladophora, with specimens C. crispula and C. montagneana, which have been transferred by the authors to Willeella as W. brachyclados. comb. nov. and W. crispula comb. nov. respectively. Cladophora catenata grouping represents a new genus with three species, C. liebetruthii a new member of the genus Microdictyon, first due to the fact diverge from clade of Anadyomene and being and distantly related to other species of Cladophora and C. liebetruthii occurred in a clade with Microdictyon species. They identified 22 species cladoforoides to the coast of Brazil, 19 species of Cladophora and three Willeella. According to this study are new taxa: the two grouping of C. coelothrix of Brazil (nom. prov.) and C. laetevirens of Brazil (nom. prov.), C. prolifera of Brasil (nom. prov.), C. rupestris of Brazil (nom. prov.), Cladophora sp. 2, Cladophora sp. 3 and Cladophora sp. 4. Five species of Cladophora were confirmed only by morphological characters: C. brasiliana, C. corallicola, C. sericea, C. socialis and C. vagabunda. Based on the results it became more evident the need for encouraging more molecular studies expanding the sampling cladophoroids taxa and using more molecular markers to better understand and elucidate the phylogenetic relationships among species. This study contributed to a broader understanding of the molecular phylogenetic relationships of the South Atlantic taxa included in the genus Cladophora and provided more data that will subsidize future investigations