Diversidade de macroalgas verdes (Ulvophyceae, Chlorophyta) do litoral de Alagoas (Brasil) com base em "DNA Barcoding"

Abstract

The green algae class, Ulvophyceae, stands out from other green algae by its diversity of macroscopic algae in marine environments, which are distributed worldwide and are richest in tropics. With a great range of morphological variability - they vary from filamentous thalli, foliose, siphonocladous to siphonaceus - the species delimitation is often being problematic due to lack of diacritic characters and high phenotypic plasticity. In the Brazilian coast, 223 species are referred, but only 39 are referred to the ~220 km coast of the Alagoas coast over five scientistic papers. Nevertheless, the Alagoas state houses 80% of the biggest federal marine Protected Area (APA Costa dos Corais) in its coast, being characterized by the abundance of reefs ecosystems. The aim of this work was to investigate the diversity of green marine macroalgae from Alagoas based on morphological and molecular data. The samples were collected in an unique collection in intertidal reefs of six localities (beaches) and 2 estuaries, from north to south of the coast, between April to August of 2019. The specimens were preserved and identified based on morphological and anatomical features in optical microscopy, following by deposition on PEUFR Herbarium (216 new accesses). Part of the material were preserved in silica gel for molecular studies, by the steps of DNA extraction, amplification, purification and sequencing. For molecular studies were generated 12 tufA and five rbcL sequences for Ulvales and Bryopsidales, 3 ITS sequences for Gayralia, 16 LSU and 12 SSU rDNA sequences for Cladophorales. Based on morphological studies, 21 genera and 54 species are referred for the Alagoas coast, with 17 being herein first referred for the region. Moreover, Boodlea struveoides and Udotea dotyi morphotypes are referred for the Brazilian coast for the first time. Based on molecular data, we confirm the identity from 17 taxa in the Alagoas coast, with U.dotyi, Ulva chaugulii and Ul. tepida being referred for the Brazilian coast for first time. The distribution of Pseudorhizoclonium mangroviorum were expanded to Brazilian Northeast coast. Chaetomopha gracilis and Ul. ohnoi are referred for the first time for Alagoas coast base on molecular data. Cladophora prolifera and C. coelothrix were reconstructed in a distinct clade from other Cladophora, and in the Brazilian coast both represents cryptic taxa. In this sense, based on SSU and LSU rDNA sequences we propose Anadyomenaceae ‘gen. et sp. nov.’ to accommodate C. coelothrix clade II (according to our analyses) representants. Our results expand the diversity known for Alagoas coast from 39 to 56 species, reinforcing the relevance of floristic surveys. Additionally, the presence of cryptic species highlights the need of the use of molecular data on marine green macroalgae identification.