Phylogeny of Gracilariaceae (Rhodophyta): evidence from plastid and mitochondrial nucleotide sequences

Abstract

Gracilariaceae are mostly pantropical red algae and include ~230 species in seven genera. Infrafamilial classification of the group has long been based on reproductive characters, but previous phylogenies have shown that traditionally circumscribed groups are not monophyletic. We performed phylogenetic analyses using two plastid (universal plastid amplicon and rbcL) and one mitochondrial (cox1) loci from a greatly expanded number of taxa to better assess generic relationships and understand patterns of character distributions. Our analyses produce the most well-supported phylogeny of the family to date, and indicate that key characteristics of spermatangia and cystocarp type do not delineate genera as commonly suggested. Our results further indicate that Hydropuntia is not monophyletic. Given their morphological overlap with closely related members of Gracilaria, we propose that Hydropuntia be synonymized with the former. Our results additionally expand the known ranges of several Gracilariaceae species to include Brazil. Lastly, we demonstrate that the recently described Gracilaria yoneshigueana should be synonymized as G. domingensis based on morphological and molecular characters. These results demonstrate the utility of DNA barcoding for understanding poorly known and fragmentary materials of cryptic red algae.

Update of the Brazilian floristic list of Algae and Cyanobacteria

“…DNA barcoding tecniques helped to perform more precise identifications and also led to the correction of former determinations that incurred in erroneous citations of taxa that, in fact, do not occur along the Brazilian coast. Some examples are publications by Sutherland et al (2011), Bahia et al (2011), Cassano et al (2012), Carvalho et al (2012), Alves et al (2012), Bahia et al (2013), Jesus et al (2013), Pellizzari et al (2013), Rocha-Jorge et al (2013), Bahia et al (2014aBahia et al ( , 2014b, Henriques et al (2014), Moura et al (2014), Nauer et al (2014a, b), Nunes et al (2014), Torrano-Silva et al (2014b), Jesus et al (2015) and Lyra et al (2015).…”

Complete chloroplast genome of Gracilaria firma (Gracilariaceae, Rhodophyta), with discussion on the use of chloroplast phylogenomics in the subclass Rhodymeniophycidae

“…Classification in the family Gracilariales has always been in a state of flux over the years, with more than hundred species passing under the generic names of Gracilaria and Hydropuntia based on the morphological and anatomical features [14–16]. It was not until the rather comprehensive molecular study based on the rbcL gene had successfully delineated the Gracilaria sensu lato into three groups which correspond to a new lineage and the previously defined genera of Gracilaria and Hydropuntia , that the systematics within Gracilariaceae was considered stabilized [14].…”

“…This study presents the complete chloroplast genome of G. firma , adding to the number of chloroplast genome available for the genus Gracilaria , one of the largest red algal genera which encompassed more than a hundred species [3] and has undergone numerous taxonomic revisions with contradicting conclusions [14–16]. Analysis of the synteny and genome structure concurred that the red algal chloroplast genomes are very compact and conserved across the subphylum Eurhodophytina, with different orders exhibiting syntenies that discriminate lineages.…”

Physiological and anatomical assessments of tetrasporophytes with epiphyte gametophytes of wild and green variant strains of Gracilaria caudata (Gracilariales, Rhodophyta)

“…This genus has 184 confirmed species (Lyra et al, 2015;Algaebase, 2017). G. caudata J. Agardh was first described in the Caribbean Sea.…”