Diversidade de algas vermelhas calcárias não articuladas (Coralinophycidae) em praias do Ceará e do Piauí

Abstract

Red macroalgae (phylum Rodophyta) include about 7,000 species divided into 830 genera. Calcareous red algae incorporate calcium carbonate (CaCO3) into their structure, and are divided into articulated and non-articulated. The non-articulated can grow as inscrutations in the sediment or forming free-living nodules, the rhodoliths. These serve as nursery and habitat for marine diversity and also act as atmospheric carbon sinks. They are grouped in the subclass Coralinophycidea. Due to the wide evolutionary convergence and simple taxonomy, algae are candidates for the use of molecular biology for phylogenetic and species resolutions, in this work the UPA, rcbL and psbA markers were used in samples collected on the beaches of Luis Correia (PI) and Pedra Rachada (CE), with the objective of performing a survey of non - articulated red algae flora through bibliographic review, exploratory sampling and analysis of DNA sequences from collected specimens. In the field, random collection followed by washing the samples in running water to remove epiphytes and after 48h stored with silica gel. The steps of protocol extraction, purification and DNA sequencing were done according to Bellorin et. Al. (2002). The sequences were aligned with MAFFT v7.017 and implemented with Geneious 8.1.8 and compared to those already available on GenBank. Neighbor-Joining trees were constructed with the Tamura-Nei genetic distance model and 10,000 replicas of bootstraps. 04 samples were sequenced for Ceará and 02 for Piauí. Paracuru samples showed affinity with the species Sporolithon episporum, Pneophyllum fragile and Phymatolithon sp, and a good alignment with sequences available in GenBank. The samples of Luis Correia presented better homology with the genus Sporolithon, but with a significant genetic distance when compared to each other, with the sequence of Paracuru and others of GenBank. Previous studies had already recorded Sporolithon episporum and Pneophyllum fragile for the state of Ceará. However, for Piauí it marks the first occurrence of non-articulated red algae. And the first record of the genus Phymatolithon in Ceará. This result may indicate a low taxon diversity for the states, where Ceará and Piauí present low diversity when compared to states with Bahia and Espírito Santo. However, the use of a larger number of samples, more molecular markers and morphological studies may help refine the data.