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Morphological and molecular studies have been performed on Laurencia dendroidea derived from Brazil and the Canary Islands. This species possesses all of the characters that are typical of the genus Laurencia, including the production of the first pericentral cell underneath the basal cell of the trichoblast; the production of tetrasporangia from particular pericentral cells without the formation of additional fertile pericentral cells; spermatangial branches that are produced from one of two laterals on the suprabasal cell of the trichoblasts; and a procarp-bearing segment that possesses five pericentral cells. The phylogenetic position of L. dendroidea was inferred by analysing the chloroplast-encoded rbcL gene sequences of 51 taxa. Phylogenetic analyses revealed that the taxa previously identified and cited in Brazil as Laurencia filiformis, L. majuscula and L. obtusa and in the Canary Islands as L. majuscula all represent the same taxonomic entity and examination of type material allowed us to identify this entity as L. dendroidea, whose type locality is in Brazil. Laurencia obtusa from the Northern Atlantic is confirmed to represent a distinct species, which displays high genetic divergence with respect to western and eastern Atlantic samples.

Within the Laurencia complex (Rhodophyta, Rhodomelaceae), six genera have been recognized based on both molecular analyses and morphology: Laurencia, Osmundea, Chondrophycus, Palisada, Yuzurua, and Laurenciella. Recently, new material from Australia has been collected and included in the current molecular phylogeny, resulting in a new clade. This study examined the generic delineations using a combination of morphological comparisons and phylogenetic analysis of chloroplast (rbcL) nucleotide sequence. The molecular phylogeny recovered eight (rather than six) clades; Yuzurua, Laurenciella, Palisada, and Chondrophycus showed as monophyletic clades each with strong support. However, the genera Osmundea and Laurencia were polyphyletic. Consequently, the new genus Coronaphycus is proposed, resulting in the new combination Coronaphycus elatus and a description of the new species C. novus.

Summary Morphological and molecular studies have been undertaken on two species of the red algal genus Laurencia J.V.Lamouroux: Laurencia majuscula (Harvey) A.H.S. Lucas and Laurencia dendroidea J.Agardh, both from their type localities. The phylogenetic position of these species was inferred by analysis of the chloroplast‐encoded rbcL gene sequences from 24 taxa. In all phylogenetic analyses, the Australian Laurencia majuscula and the Brazilian L. dendroidea formed a well‐supported monophyletic clade within the Laurencia sensu stricto. This clade was divided into two subclades corresponding to each geographical region; however, the genetic divergence between Australian L. majuscula and Brazilian L. dendroidea was only 0–1.35%. Examination of the type specimens and sequences of freshly collected samples of both Laurencia majuscula and L. dendroidea show the two to be conspecific despite their disjunct type localities.

It was noted that Mediterranean specimens collected at different stations from around Sicily, Italy and referred to as Laurencia dendroidea (as Laurencia majuscula) were similar to the recently described species Laurenciella marilzae. Presented in this study are the results of an integrative approach using both morphology and molecular data (COI-5P + rbcL) to establish which taxon these specimens should be referred to. Molecular analyses show these specimens belong to Laurenciella, and strongly suggest they are within the species L. marilzae. Morphological examinations of these Mediterranean specimens were also detailed and found to support the conclusion that they belong to L. marilzae.

In spring 2014, thousands of green algal balls were washed up at Dee Why Beach, Sydney, New South Wales, Australia. Reports of algal balls are uncommon in marine systems, and mass strandings on beaches are even more rare, sparking both public and scientific interest. We identified the algal masses as

Laurencia majuscula has recently been determined to be conspecific with Laurencia dendroidea. To determine the correct taxonomic placement of its only non-typical variety, L. majuscula var. elegans, mitochondrial COI-5P and chloroplast rbcL gene sequences were analyzed and its phylogenetic position was inferred. Laurencia majuscula var. elegans consistently formed a well-supported clade distinctly separate from the L. dendroidea clade. Molecular analyses revealed that L. majuscula var. elegans generally shows two distinct forms; a long-branched form, and a compact form. Often the compact form has been identified as a different species based on morphology alone. Included in these analyses were topotype sequences of two species with which L. majuscula var. elegans is most often misidentified; Laurencia nidifica and Laurencia mcdermidiae. Laurencia nidifica formed a wellsupported clade separate from L. majuscula var. elegans. Laurencia mcdermidiae, however, formed a well-defined clade sister to the L. majuscula var. elegans clade. Morphological comparisons were also made. It is concluded that L. majuscula var. elegans is morphologically distinct from L.dendroidea, L. nidifica, and L. mcdermidiae. It is proposed that L. majuscula var. elegans be reinstated to species level as L. elegans.

Inspecting herbaria collections of Laurencia rigida highlighted frequent misidentifications between L. rigida and L.heteroclada f. decussata, two poorly studied taxa from Australia. Recent collections of DNA material, including from topotypematerial, allowed for re-examination of these two taxa using molecular techniques. Detailed morphological andmolecular analyses based on two markers (rbcL and COI-5P) strongly supported these two taxa as being distinct fromeach other and requiring nomenclatural changes. Comprehensive morphological analyses highlighted features useful foraccurate identifications. Interestingly, L. rigida was found to belong to the genus Palisada with evidence from both themorphology and molecular data. Therefore, this study proposed recognizing L. rigida as Palisada rigida comb. nov. Moleculardata for L. heteroclada f. decussata on the other hand supported its separation from L. heteroclada, with too greata molecular distance to be considered a variety. Morphological characters that best separated P. rigida from L. decussataincluded seven characters; number of pericentral cells per vegetative axial segment, the presence of secondary pit connections,the presence of lenticular thickenings, tetrasporangia alignment, the presence of corps en cerise, holdfast morphology,and overall plant shape. Morphologically, L. heteroclada f. decussata was also separated from L. heteroclada,particularly by the following characteristics; ultimate branchlets morphologies, lower order branch lengths, primary axisand holdfast morphologies. Therefore, it was proposed that L. heteroclada f. decussata is recognized at a species level asL. decussata comb. et stat. nov.