<strong>DIVERSITY OF GRACILARIACEAE (RHODOPHYTA) IN BRAZIL: INTEGRATING MORPHOLOGICAL AND MOLECULAR DATA</strong>

Abstract

The Gracilariaceae comprises 242 mainly tropical species, including some with significant economic value for the food and pharmaceutical industry. Accurate taxonomy is crucial for the selection of species for cultivation. However, species identification is still challenging taxonomists. Nineteen species of Gracilariaceae have so far been referred to the Brazilian coast. We describe this diversity across approximately 32 degrees of latitude, using mitochondrial (COI-5P) and plastid (UPA and rbcL) markers in species delimitation analyses (ABGD and SPN). We provide phylogenetic (based on a concatenated three-genes tree and a taxa rich rbcL tree) and barcoding analyses from a broad and partially original collection combined with morphoanatomical data, including information resulting from analyses of type specimens and topotype material. We identified twenty-five specific entities occurring on the Brazilian coast, including four new species yet to be described. Spermatangial arrangements and aspects of thallus morphology were the most useful characters for species and genera delimitation, while characters based on the anatomy of the cystocarp overlap. Our morphological analyses demonstrate the lack of exclusive characters that justify the recently proposed Gracilariaceae infrafamilial categories, and therefore we use in this work the Gracilaria sensu lato genus concept. We provide descriptions, illustrations and a dichotomous key for the identification of species occurring in Brazil.

Molecular assessment of the species of Gracilariaceae (Gracilariales, Rhodophyta) from the Yucatan Peninsula, Mexico, including two new records for the Mexican Atlantic

“…Consequently, genera previously described as independent from Gracilaria O n l i n e f i r s t due to their paraphyletic position in the phylogeny (Gurgel et al 2018(Gurgel et al , 2020, have been merged back into a single genus (Lyra et al 2021). Crassiphycus was one of the genera included in a broadly circumscribed Gracilaria sensu lato proposed by Lyra et al (2021). However, from our phylogenetic analysis, we recognize Crassiphycus as an independent genus of Gracilaria.…”

“…However, from our phylogenetic analysis, we recognize Crassiphycus as an independent genus of Gracilaria. Likewise, in the study by Lyra et al (2021), Crassiphycus usneoides was not included within the diversity of Gracilariaceae in Brazil, because they did not molecularly confirm its presence and discussed, in agreement with Núñez-Resendiz et al (2015), the difficulty of recognizing them morphologically. Previously, C. usneoides was included as part of a complex of cryptic species along with C. corneus by Núñez-Resendiz et al (2015), both species with type localities in Brazil.…”

“…Considering the values of the interspecific distances, the morphological similarity between several species in the Gracilariaceae, and the results using DNA species delimitation methods, it seems that some species in the family have been wrongly described as new diversity; consequently, they must be critically reviewed. For example, in a very recent study (Lyra et al 2021), the floristic diversity for the Gracilariaceae species from Brazil was discussed under morphological and molecular evidence. Consequently, genera previously described as independent from Gracilaria O n l i n e f i r s t due to their paraphyletic position in the phylogeny (Gurgel et al 2018(Gurgel et al , 2020, have been merged back into a single genus (Lyra et al 2021).…”

“…For example, in a very recent study (Lyra et al 2021), the floristic diversity for the Gracilariaceae species from Brazil was discussed under morphological and molecular evidence. Consequently, genera previously described as independent from Gracilaria O n l i n e f i r s t due to their paraphyletic position in the phylogeny (Gurgel et al 2018(Gurgel et al , 2020, have been merged back into a single genus (Lyra et al 2021). Crassiphycus was one of the genera included in a broadly circumscribed Gracilaria sensu lato proposed by Lyra et al (2021).…”

Phylogeography of the red alga Gracilariopsis tenuifrons (Gracilariales) along the Brazilian coast

“…Gracilariopsis tenuifrons is an intertidal rocky shore species with a wide geographical distribution occurring from Mexico to Brazil. In Brazil, G. tenuifrons is observed between Maranhão state (2°48′64.3" S) and Santa Catarina state (27.5°73′83" S) (Lyra et al, 2021). The occurrence of this species on the Brazilian coast stretches across 7900 km and three of the biogeographic provinces proposed by Spalding et al (2007); (Figure 1).…”