Dictyota chalchicueyecanensis sp. nov. (Dictyotales, Phaeophyceae) in the Gulf of Mexico: Molecular and Morphological Evidence

Abstract

Background. Species of the Dictyota genus have a high phenotypic plasticity that contrasts with their limited morphological diagnostic characteristics, which has led to some uncertainty in identifying species in the Gulf of Mexico. Recent studies worldwide have focused on Dictyota species phylogenies, which are the basis for contrasting and interpreting the results of this study. Goals. In our research, we found evidence of a new species belonging to the Dictyota genus in three localities in the state of Veracruz, Mexico (Playa Hermosa, Punta Puntillas y Villa Rica). Methods. Phylogenetic and
molecular analyses of partial sequences of the psbA and cox1 genes were performed, complemented by morphological analysis. Results. In phylogenetic analysis of partial sequences of psbA and cox1, we established that samples of the new species form a well-supported monophyletic clade. In addition, the genetic divergence values that were obtained are within the interspecific values for the genus, allowing us to segregate the Dictyota chalchicueyecanensis sp. nov. from the
rest of the species of this genus. Morphologically this new species is characterized by an erect thallus, light brown and lacking iridescence, stiff to the touch, with a discoid holdfast, rounded apices, dichotomous branching, dentated margins, with minute teeth, triangular to spinose in shape that are directed toward the apices. Sporangia are isolated or grouped on both sides of the thallus and germinate regularly in interdichotomous basal portions. Conclusion. These results allow us to expand the diversity of the genus Dictyota worldwide, incorporating D. chalchicueyecanensis as a probable new
species endemic to Mexico.