Updates on Section Pseudo-opuntia of Halimeda: phylogenetic analyses of H. soniae sp. nov. (Bryopsidales, Chlorophyta) along the Brazilian coast

Abstract

Halimeda is a genus of green seaweed showing high morphological plasticity. Studies using molecular markers for species delimitations and phylogenetics have revealed cryptic diversity and new species throughout the world. Seven species of Halimeda are currently recognized in Brazil. The present study describes the new species Halimeda soniae Ximenes, Oliveira-Carvalho, M. E. Bandeira-Pedrosa et Cassano sp. nov. to accommodate the taxon previously identified as Halimeda aff. gracilis for Brazil. Samples of H. soniae were collected in Espírito Santo State (southeastern Brazil), and plastid gene sequences of tufA and rbcL were obtained. Phylogenetic analyses showed that H. soniae belongs to Section Pseudo-opuntia, together with Halimeda gracilis and Halimeda lacrimosa; the three species have overlapping morpho-anatomical features. Phylogenetic analyses suggest that H. gracilis is restricted to the Indo-Pacific Ocean, whereas the other two species appear to be restricted to the Atlantic. Additional research on Caribbean specimens will be necessary to resolve the taxonomic position of the taxa named as H. lacrimosa and H. gracilis in that region. Based on our results, H. gracilis does not occur in the Brazilian marine flora.

First molecular analysis of the genus Bryopsis (Bryopsidales, Chlorophyta) from Brazil, with an emphasis on the Pernambuco coast

“…However, the range of intraspecific divergence value for tufA observed in this study for Brazilian samples (0-1.57 %) is relatively within the range of variation found for other Bryopsidalean genera, such as Halimeda (0-1.4 %) (Ximenes et al 2019). The interspecific divergence observed for tufA (3.3-16.2 %) is relatively within the range reported for Halimeda, 0.9-12.4 % by Ximenes et al (2017) and 2.0-6.2 % by Ximenes et al (2019), as well as for Codium (Bryopsidales), 1.44-14.65 %, and Ulva (Ulvales), 0.91-9.1 % reported by Saunders & Kucera (2010) Intraspecific divergence within Bryopsis for rbcL (0-0.4 %) was lower than that observed for Halimeda (0.8-1.2 %) by Ximenes et al (2019), whereas the range of interspecific variation for this marker (6.7-11.6 %) is within the range reported for Halimeda, 0.8-11.7 % by Ximenes et al (2017) and 4.5-5.0 % by Ximenes et al (2019). For the psbB marker, Tufiño-Velázquez & Pedroche (2019) proposed a genetic distance range between 5 % to 12 % for species discrimination and, therefore, considered a distance of up to 4.9 % as intraspecific, a higher value than that obtained for tufA and rbcL in this study.…”