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Revealing the diversity of the genus Ulva (Ulvales, Chlorophyta) in southeastern Brazil, with a description of Ulva kanagawae sp. nov.

ABSTRACT The green algal genus Ulva is one of the most widely distributed macroalgal genera. The taxonomy of Ulva is problematic due to its simple morphology. The study of the diversity of this genus has undergone great advances using molecular data, leading to changes in the taxonomic status of species, and the recognition of species complexes and cryptic species. Here we reassessed Ulva species from southeastern Brazil using molecular data. We recognized 10 taxa, among which only three previously reported species were confirmed by molecular data: U. compressa, U. lactuca and U. ohnoi, the latter recently recorded from insular waters in Fernando de Noronha Archipelago, northeastern Brazil. Our phylogenetic analyses and species delimitation methods strongly supported the establishment of Ulva kanagawae sp. nov. The species traditionally cited for southeastern Brazil, U. flexuosa, U. linza, U. rigida and U. paradoxa, proved to be misapplied names of U. tepida, U. aragoënsis, U. ohnoi/U. lactuca and U. torta, respectively. One taxon, Ulva sp., remains unnamed and needs further studies. Ulva chaugulei and U. tanneri, both considered here as cryptogenic species, are new occurrences for Brazil expanding their geographic distribution to the Atlantic Ocean and western Atlantic Ocean, respectively. In addition, our analysis of sequences from type materials revealed that U. pseudo-ohnoi is a heterotypic synonym of U. conglobata. This first systematic molecular study of Ulva species in Brazil points out that more extensive sampling is needed to reveal the true diversity of the genus in Brazilian waters.

Systematic revision of the Grateloupia complex (Rhodophyta) from Vietnam using rbcL and LSU sequences, with the description of Phyllymenia nhatrangensis sp. nov.

ABSTRACT Grateloupia sensu lato has had a long and troublesome taxonomic history because of superficial similarities in morphology, ill-defined species boundaries and lack of diagnostic characters that leave many gaps that still need to be fully resolved. In this study, we carried out detailed observations on female reproductive structures, and inferred the phylogenetic relationships of the Grateloupia-like species occurring in Vietnam based on rbcL and LSU rDNA sequence analyses. The new species Phyllymenia nhatrangensis sp. nov. differs from its sister species P. gibbesii in the thickness of the cortex. The new species is slightly flattened, composed of two to four main blades, bearing numerous marginal and a few superficial, lanceolate bladelets. Blade sizes of P. nhatrangensis are also smaller than those of P. gibbesii, which are longer and wider. However, the new species shares with species from western Pacific Ocean, such as P. taiwanensis and P. huangiae, the presence of frequent marginal proliferations. Based on rbcL, the divergence between P. nhatrangensis and P. gibbesii was 3.3% (39 bp). With the present addition, Grateloupia sensu lato now comprises 16 species, including nine species of Grateloupia, three species of Phyllymenia, two species of Yonagunia and one species each of Dermocorynus and Prionitis.

Studies on the complex Warnowiaceae (Dinophyceae) I. Lohmann’s Pouchetia parva refound and renamed Nematodinium parvum comb. nov. (= Warnowia parva)

ABSTRACT The dinoflagellate family Warnowiaceae has often been considered to include some of the most complex cells among the protists. The number of described species is around 40, but both the species and generic concepts are in need of revision. Warnowiaceans are often fragile and readily change morphology under the light microscope, and they are usually regarded to be rare. They are particularly famous for the eye-like structures, termed ocelloids. Studies on warnowiaceans are hampered by lack of cultures, and our studies are therefore based on cells obtained directly from field samples. We provide a description of Nematodinium parvum comb. nov. (syn. Pouchetia parva, Warnowia parva), based on light, scanning and transmission electron microscopy, combined with phylogenetic analyses of ribosomal genes. It was described in 1908 by Lohmann from Kieler Bay, but is often common in Danish waters, allowing observations on distribution and behaviour. Crucial conditions for finding high cell abundances were periods of warm temperatures and a calm sea. Cells were yellowish, photosynthetic, and contained a net-like chloroplast, in addition to an ocelloid, trichocysts and harpoon-like nematocysts. They divided asexually but planozygotes were also seen. Following the demonstration of nematocysts, the species, which has been known as Warnowia parva since 1928, is transferred to Nematodinium. The finding of a peduncle indicates mixotrophy but all feeding experiments failed to identify a suitable prey. The phylogenetic analyses based on single-cell PCR and sequence determinations of small and large subunit rDNA confirmed that the systematics of Nematodinium and Warnowia is in a state of flux.

Open Access
Species diversity and molecular phylogeny of Crustaphytum and Mesophyllum (Hapalidiales, Rhodophyta) from the Asian Pacific, including three new species of Crustaphytum

ABSTRACT The non-geniculate coralline algal genus Crustaphytum occurs in subtropical regions of the Pacific and Atlantic Oceans and presently contains only two species, C. pacificum and C. atlanticum. In contrast, the genus Mesophyllum is more widely reported and has representative species in both warm and cold waters. We analysed the species diversity of collections of Crustaphytum and Mesophyllum-like specimens from the Asian-Pacific region, based on psbA and rbcL sequence analyses and morphology. Our molecular analyses showed that the collections of Mesophyllum-like specimens mostly belonged to Crustaphytum with only a few specimens clustering with the Mesophyllum/Melyvonnea complex. We also describe three new species of Crustaphytum (C. taiwani-boreale sp. nov., C. taoyuanense sp. nov. and C. fragile sp. nov.) that are commonly found in the algal reefs in Northwest Taiwan, utilizing both scanning electron and light microscopy, and DNA sequence analyses. Crustaphytum fragile (79–95 μm thick) and Crustaphytum taiwani-boreale (235–436 μm thick) mostly grow in similar habitats in the algal reefs and can only be distinguished by a combination of characters relating to tetrasporangial chamber size and the number of cell layers in the cortex and medulla. Crustaphytum taoyuanense (233–300 μm thick) can be separated from the other species by its violet-red colour and by the margins of older thalli becoming overgrown by adjacent thalli. Crustaphytum taoyuanense and C. fragile are restricted to Taoyuan City in Northwestern Taiwan, whereas C. taiwani-boreale has a broader distribution in Northern Taiwan. Our study reveals a rich species diversity of Crustaphytum in the warm water region of the Western Pacific Ocean.

Asia Pacific Sporolithon (Corallinophycidae, Rhodophyta) species revised based on DNA sequencing of type specimens and including S. crypticum sp. nov., S. immotum sp. nov. and S. nodosum sp. nov.

ABSTRACT To address the taxonomic uncertainty of Sporolithon species named in the early to mid-20th century, targeted PCR sequencing was performed on eight historical type specimens and on recently collected specimens. Six type specimens amplified for the rbcL gene and were Sanger sequenced yielding sequences ranging in length from 118 to 280 base pairs (bp). One, S. australasicum, failed to amplify and another, S. howei, was amplified for the psbA gene yielding a sequence 544 bp in length. The 118 bp long rbcL sequence of the lectotype of S. crassiramosum showed that it is a later, heterotypic synonym of S. molle. The rbcL sequences of type specimens of S. episoredion, S. schmidtii, S. sibogae and S. timorense ranged from 118 to 228 bp, and each is a distinct species. The 544 bp long psbA sequence of S. howei is also unique. The 280 bp long rbcL sequence of the lectotype of S. durum did not match any sequence with that name in any public repository, including the previously published complete plastome and mitogenome sequences. However, it was identical in sequence to a specimen in GenBank from the southern coast of Western Australia as well as several other sequences generated from field-collected specimens from the states of South Australia and Western Australia. The rhodolith specimens from New Zealand previously called S. durum are S. nodosum sp. nov. The species is endemic to New Zealand. The epilithic specimens from New Zealand previously called S. durum are S. immotum sp. nov., which is also found along the southeastern coast of Australia. Sporolithon crypticum sp. nov. is described from the southern coast of Western Australia. RAxML and Bayesian phylogenetic analyses of Sporolithon psbA and rbcL sequences are congruent between the two plastid encoded genes. DNA sequencing of type specimens of species of corallines is demonstrated to be the only reliable method to correctly apply names.

New insights into post-fertilization in Dudresnaya (Gigartinales, Rhodophyta) and Acrosymphyton (Acrosymphytales, Rhodophyta)

ABSTRACT Dudresnaya (Dumontiaceae, Gigartinales) and Acrosymphyton (Acrosymphytaceae, Acrosymphytales) are florideophycean genera (Rhodophyta) traditionally described as presenting a typical non-procarpic behaviour. The post-fertilization stages of their corresponding generitypes, D. verticillata and A. purpuriferum, have been described on many occasions. Nevertheless, some recent observations led the authors of this study to look more deeply into the development of the carpogonial and auxiliary fusion cells in the generitypes. Main results include a) description of the carpogonial fusion cell development by secondary connection (via fusion in D. verticillata and via conjunctor cells in A. purpuriferum); b) assessment of the existence, prior to diploidization, of primary auxiliary fusion cells in both species, and the description of their development and also that of the auxiliary fusion cells; and c) observation of occasional procarpic behaviour in both species, with gonimoblast developing from the secondary connecting filament initials in D. verticillata and from the carpogonial fusion complex in A. purpuriferum. The study has increased the understanding of the post-fertilization processes and supports the hypothesis that the procarpic behaviour is secondarily derived from non-procarpic ancestors.