Marine macroalgae, especially the Rhodophyta, can be notoriously difficult to identify owing to their relatively simple morphology and anatomy, convergence, rampant phenotypic plasticity, and alternation of heteromorphic generations. It is thus not surprising that algal systematists have come to rely heavily on genetic tools for molecular assisted alpha taxonomy. Unfortunately the number of suitable marker systems in the three available genomes is enormous and, although most workers have settled on one of three or four models, the lack of an accepted standard hinders the comparison of results between laboratories. The advantages of a standard system are obvious for practical purposes of species discovery and identification; as well, compliance with a universal marker, such as cox1 being developed under the label 'DNA barcode', would allow algal systematists to benefit from the rapidly emerging technologies. Novel primers were developed for red algae to PCR amplify and sequence the 5 0 cox1 'barcode' region and were used to assess three known species-complex questions: (i) Mazzaella species in the Northeast Pacific; (ii) species of the genera Dilsea and Neodilsea in the Northeast Pacific; and (iii) Asteromenia peltata from three oceans. These models were selected because they have all caused confusion with regards to species number, distribution, and identification in the field, and because they have all been studied with molecular tools. In all cases the DNA barcode resolved accurately and unequivocally species identities and, with the enhanced sampling here, turned up a variety of novel observations in need of further taxonomic investigation.
A group of protist experts proposes a two-step DNA barcoding approach, comprising a universal eukaryotic pre-barcode followed by group-specific barcodes, to unveil the hidden biodiversity of microbial eukaryotes.
Every year numerous ecological, biochemical, and physiological studies are performed using members of the order Laminariales. Despite the fact that kelp are some of the most intensely studied macroalgae in the world, there is significant debate over the classification within and among the three ''derived'' families, the Alariaceae, Laminariaceae, and Lessoniaceae (ALL). Molecular phylogenies published for the ALL families have generated hypotheses strongly at odds with the current morphological taxonomy; however, conflicting phylogenetic hypotheses and consistently low levels of support realized in all of these studies have resulted in conservative approaches to taxonomic revisions. In order to resolve relationships within this group we have sequenced over 6000 bp from regions in the nuclear, chloroplast, and mitochondrial genomes and included 42 taxa in Bayesian, neighbor-joining, and parsimony analyses. The result is the first comprehensive and well-supported molecular phylogeny for the ALL complex of the Laminariales. We maintain the three recognized families (Alariaceae, Laminariaceae, and Lessoniaceae), but with vastly different compositions, as well as propose the Costariaceae fam. nov. for Agarum, Costaria, Dictyoneurum, and Thalassiophyllum, the only genera in the Laminariales with flattened, occasionally terete, stipes and either a perforate or reticulate blade. In addition, our data strongly support a split of the genus Laminaria. We resurrect the genus Saccharina Stackhouse for the Laminaria clade that does not contain L. digitata (Hudson) J.V. Lamouroux, the type of the genus.
Pelagomonas calceolata gen. et sp. nov., an ultra‐planktonic marine alga, is described using electron microscopy and the cytoplasmic small subunit (18S) ribosomal RNA (rRNA) gene sequence. Cells are uniflagellate, about 1.5 × 3 μm in size. The flagellium has two rows of bipartite hairs, the paraxonemal rod has a dentate appearance, and a two‐gyred transitional helix is present between two transitional plates. Microtubular roots, striated roots, and a second basal body are absent. A thin organic theca surrounds most of the cell. There is a single chloroplast with a girdle lamella and a single, dense mitochondrion with tubular cristae. A single Golgi body with swelled cisternae lies beneath the flagellum, and each cell has an ejectile organelle that putatwely releases a cylindrical structure. A vacuole, or cluster of vacuoles, contains the putative carbohydrate storage product. The 18S rRNA gene was sequenced completely in both directions, excluding three primer regions. When compared to the same gene sequence from other organisms, Pelagomonas calceolata gen. et sp. nov. occupies an unresolved position among other chromophyte algae and is distinct from members of any of these classes. Based on morphological, ultrastructural, and molecular data, we describe this alga as a new species, and we place this highly unusual new species in a new genus, family, order, and class.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.