Molecular assessment of Ulva (Ulvales, Chlorophyta) diversity in Vietnam including the new species U. vietnamensis

Abstract

Species diversity of Ulva in Vietnam was investigated using three commonly used genetic markers, the nuclear encoded rDNA ITS region and the plastid encoded rbcL and tufA genes. Single locus species delimitation methods, complemented with morphological and ecological information resulted in the delimitation of 19 species. This diversity is largely incongruent with the traditional understanding of Ulva diversity in Vietnam. Only four species identified in this study, U. lactuca, U. reticulata, U. spinulosa, and U. flexuosa, have been previously reported, and seven species, U. ohnoi, U. tepida, U. chaugulii, U. kraftiorum, U. meridionalis, U. limnetica, and U. aragoënsis, are recorded for the first time from Vietnam. Seven genetic clusters could not be associated with species names with certainty. A new species, U. vietnamensis, is described from marine to brackish coastal areas from southern Vietnam based on its morphological and molecular distinctiveness from the currently known Ulva species. A comparison with recent molecular-based studies of Ulva diversity showed that species composition in Vietnam is similar to that of adjacent countries, including Japan, China, as well as Australia. Our study emphasizes the importance of molecular data in the assessment of Ulva diversity, and indicates that a lot of diversity may still remain to be discovered, especially in tropical regions.

Marine Floral Biodiversity, Threats, and Conservation in Vietnam: An Updated Review

“…For Chlorophyta, the only molecular-assisted alpha taxonomic study reported until now is that by Tran et al [61], who reassessed the species diversity in Vietnam of the Ulvaceae genus Ulva based on rbcL and the elongation factor Tu (tuf A). The study revealed seven new records of Ulva from Vietnam and identified a new species, U. vietnamensis L-A.…”

Morphological and Molecular Identification of Ulva spp. (Ulvophyceae; Chlorophyta) from Algarrobo Bay, Chile: Understanding the Composition of Green Tides

“…By using phylogenetic analyses, DNA markers have facilitated species determination within Ulva (e.g., [34][35][36]). For the genus Ulva, sequences of the elongation factor Tu (tuf A) of the chloroplast genome have been shown to exhibit adequate variation for species resolution and are widely used to assess species diversity (e.g., [34][35][36][37][38][39][40][41][42][43][44][45][46]). Other markers that have proven useful for species identification and often complement data from tuf A or other chloroplast sequences are the Cytochrome Oxidase I (COI) gene encoded in the mitochondrial genome (e.g., [47]) and sequences of internal transcribed spacer ITS from the nuclear genome [32,[34][35][36][37][38]42].…”