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We analyzed mitochondrial COI-5P and plastid rbcL sequences from specimens of Aphanta collected from China and Japan and accessed morpho-anatomical data in detail. The results revealed the presence of a novel species of this genus, Aphanta asiatica, described here. Aphanta asiatica was characterized by a turf-forming habit of thalli with anastomosing branches, and a thick, wide, and flattened axis with subpinnate to pinnate branches, and characterized by its robust and branched prostrate system bearing complex peg-like haptera which were either typical or non-typical. Rhizoidal filaments were abundant in the inner cortex and distal ends of the axis, and interspersed in the medulla. Tetrasporangial and spermatangial sori were produced on the terminal ends of the branchlets and axes. Tetrasporangia were irregularly arranged and cruciately divided, and spermatangia were cut off from the outermost cortical cells. In phylogenies of the COI-5P and rbcL sequences, A. asiatica was closely related to Aphanta pachyrrizha. In conclusion, the present study is the first to document reproductive structures in, and contribute further to our understanding of, the genus Aphanta.

In the current study, 334 specimens of Pterocladiella from China representing historical herbarium specimens and recent field collections were re-examined based upon morphological and molec...

© 2019 Japanese Society of Phycology Flattened Gracilaria species are widely distributed along the coasts of the South China Sea with more than 20 species recorded. Within the South China Sea, Gracilaria mammillaris has only been reported from Vietnam, but this species is likely restricted to the western Atlantic. This study aimed to reevaluate the taxonomic status of Vietnamese specimens of ‘G. mammillaris’ using combined morphological and molecular data. Our data clearly indicated that Vietnamese specimens were morphologically and genetically distinct from authentic G. mammillaris from the western Atlantic, and also other described flat Gracilaria species. We, therefore, propose that specimens from Vietnam originally identified as G. mammillaris be designated as a new species, Gracilaria phuquocensis sp. nov. Morphologically, G. phuquocensis can be distinguished from other flat Gracilaria species by its small thallus size, narrower blades, many medullary layers, abundant basal nutritive filaments within mature cystocarps, and tetrasporangial nemathecium. Our rbcL sequence analyses showed that the new species was sister to Gracilaria rhodymenioides from Thailand, and these two species formed a clade with cylindrical Gracilaria species. Our study contributes to clarification of the taxonomic status of misidentified specimens attributed to the flattened Gracilaria species in the South China Sea.

Molecular phylogeny of Eudesme specimens collected from various localities in the Northern Hemisphere using mitochondrial cox1 and cox3 and chloroplast atpB, psaA, psbA and rbcL gene sequen...

The evolutionary influences of historical and contemporary factors on the population connectivity and phylogeographic structure of a brown seaweed, Sargassum ilicifolium, were elucidated using the nuclear ITS2 and mitochondrial COI markers for the collections newly sampled within its distribution range in the northwestern Pacific (NWP). Significant genetic structure at variable levels was identified between populations (pairwise FST ) and among populations grouped by geographical proximity (ΦCT among regions). The adjacent groups of populations with moderate structure revealed from AMOVA appeared to have high genetic connectivity. However, a lack of genealogical concordance with the geographic distribution was uncovered for S. ilicifolium from the NWP. Such genetic homogeneity is interpreted as a result of the interaction between postglacial recolonization and dynamic oceanic current regimes in the region. Two separated glacial refugia, the South China Sea and the Okinawa Trough, in the marginal seas of east China were recognized based on the presence of endemic haplotypes and high haplotype diversity in the populations at southern China and northeast of Taiwan. Populations persisting in these refugia may have served as the source for recolonization in the NWP with the rise of sea level during the warmer interglacial periods. The role of oceanic currents in maintaining genetic connectivity of S. ilicifolium in the region was further corroborated by the coherence between the direction of oceanic currents and that of gene flow, especially along the eastern coast of Taiwan. This study underlines the interaction between historical postglacial recolonization and contemporary coastal hydrodynamics in contributing to population connectivity and distribution for this tropical seaweed in the NWP.

To examine optimal growth conditions of the edible green alga Caulerpa okamurae, thalli of this species were cut into erect frond (3 cm long) and stolon (5 cm long) fragments. They were cultured in combinations of four temperatures (15, 20, 25, and 30 °C), three irradiances (20, 40, and 80 μmol photons m−2 s−1), four daylengths (8, 12, 16, and 24 h), and seven salinities (15, 20, 25, 30, 35, 40, and 45 psu). After 12 days, maximal relative growth rates (RGRs) for erect fronds (6.78% day−1) and stolons (7.02% day−1) occurred at 25 °C and 40 μmol photons m−2 s−1. At 30 °C, growth differences were found; negative growth for erect fronds and positive growth for stolons, with an average RGR of 1.96% day−1. A daylength of 16 h and salinity of 30 psu were needed for maximal growth of erect fronds and stolons. Stolon exhibited a greater tolerance to high and low temperatures and low salinity than erect fronds. Thalli weight of C. okamurae was increased by increments of stolon length, new erect fronds, and new ramuli. In conclusion, C. okamurae should be cultivated in summer with high seawater temperature (25 °C) and long daylength, in waters of 30 psu, and at a water depth providing 40 μmol photons m−2 s−1. These physiological and growth pattern data are informative for the successful development of commercial cultivation of C. okamurae.

Many studies classifying Gracilaria species for the exploitation of agarophytes and the development of the agar industry were conducted before the prevalence of molecular tools, resulting in the description of many species based solely on their morphology. Gracilaria firma and G. changii are among the commercially important agarophytes from the western Pacific; both feature branches with basal constrictions that taper toward acute apices. In this study, we contrasted the morpho-anatomical circumscriptions of the two traditionally described species with molecular data from samples that included representatives of G. changii collected from its type locality. Concerted molecular analyses using the rbcL and cox1 gene sequences, coupled with morphological observations of the collections from the western Pacific, revealed no inherent differences to support the treatment of the two entities as distinct taxa. We propose merging G. changii (a later synonym) into G. firma and recognize G. firma based on thallus branches with abrupt basal constrictions that gradually taper toward acute (or sometimes broken) apices, cystocarps consisting of small gonimoblast cells and inconspicuous multinucleate tubular nutritive cells issuing from gonimoblasts extending into the inner pericarp at the cystocarp floor, as well as deep spermatangial conceptacles of the verrucosa-type. The validation of specimens under different names as a single genetic species is useful to allow communication and knowledge transfer among groups from different fields. This study also revealed considerably low number of haplotypes and nucleotide diversity with apparent phylogeographic patterns for G. firma in the region. Populations from the Philippines and Taiwan were divergent from each other as well as from the populations from Malaysia, Thailand, Singapore and Vietnam. Establishment of baseline data on the genetic diversity of this commercially important agarophyte is relevant in the context of cultivation, as limited genetic diversity may jeopardize the potential for its genetic improvement over time.

In order to study the effect of temperature, irradiance, and salinity on the asexual reproduction of Caulerpa lentillifera, we conducted the indoor culture to study these factor effects on the regeneration of C. lentillifera, together with the measurement of photosynthetic parameters such as chlorophyll content, fluorescence characteristics, and rbcL behavior. It was shown that the maximum specific growth rate (SGR) of the alga was at 27.5 A degrees C and 40 mu mol photons m(-2) s(-1), and warm temperature (25.0-30.0 A degrees C) induced the formation of branches. Both lower and higher temperature reduced chlorophyll content and decreased F (v)/F (m) value, while high rbcL expressions occurred at 27.5 A degrees C. With the irradiance rise, the chlorophyll content decreased and the higher irradiance (100 mu mol photons m(-2) s(-1)) decreases F (v)/F (m) and increases of NPQ. The higher irradiances (40 and 100 mu mol photons m(-2) s(-1)) also reduced rbcL expression. This physio-ecological data will be valuable to explore the possible asexual propagation of this green alga and eventually for future large-scale vegetative reproduction.

Sun Z., Hanyuda T., Lim P.E., Tanaka J., Gurgel C.F.D. and Kawai H. 2012. Taxonomic revision of the genus Lobophora (Dictyotales, Phaeophyceae) based on morphological evidence and analyses rbcL and cox3 gene sequences. Phycologia 51: 500–512. DOI: 10.2216/11-85.1 A taxonomic revision of Lobophora based on molecular phylogenetic analyses of rbcL and cox3 gene sequences as well as anatomical observations was carried out, mostly based on specimens collected from eastern Asia and southeastern Australia. In the molecular phylogenetic analyses, nine major clades supported by high bootstrap values were recognized. In combination with evaluation of morphological characters, four clades were concluded to be new species. The Australian species L. australis sp. nov. possessed erect thalli with sporangial sori scattered on the ventral surface and had a closer phylogenetic relationship with another Australian species, L. nigrescens, but it was distinguished from the latter in having fewer layers of cortical cells and ...

The species-level taxonomy of the marine brown algal genus Sargassum is problematic. To resolve some of these systematic issues in the northern China seas, a molecular analysis of Sargassum species was carried out using ITS-2, cox3, and rbcL DNA sequences. Phylogenetic analyses confirmed eight species, including: S. confusum, S. fusiforme, S. hemiphyllum var. chinense, S. horneri, S. muticum, S. siliquastrum, S. thunbergii, and S. vachellianum. The previously described S. shandongense and S. qingdaoense, endemic to the Shandong Peninsula, are shown to be synonymous with S. vachellianum. Seven species previously described from the East China Sea were not observed, and require further investigation.

Microcostatus salinus, an epipsammic species, is described from estuarine intertidal sediments in Japan. Its morphology was examined with light, scanning and transmission electron microscopy. Microcostatus salinus possesses two unique morphological features differing from all other species in this genus, viz., i) the striae are composed of two elongate areolae and restricted to the area near valve apexes, and ii) the distance between the two central raphe endings on the external valve surface is about two times longer than that on the internal one. In addition, M. salinus is the only species of the genus Microcostatus found from brackish to saline environments.

Fallacia decussata is described as a new marine littoral diatom from Northeast Asia. Its morphology was examined with light, scanning and transmission electron microscopy. Fallacia decussata has a unique feature, viz., possessing 2–4 pores on each side of raphe terminal fissures, while all congeners have either invariably a single pore or only a slit. This species differs from congeners also by a combination of morphological features including: i) elliptical valves with broadly round poles; and ii) convex and centrally strongly constricted lateral sterna, forming a more or less X-shaped central area; iii) striation density of 25–28 in 10 μm. This species is an epipsammic diatom currently known from intertidal zone in the northwest Pacific Ocean.

Part of the definition of Psammodiscus is that there is always a small pore and sometimes a rimoportula present on the valve centre. A new species Psammodiscus calceatus Tsuy.Watanabe, Nagumo & J. Tanaka is described, which lacks a central small pore. And the valves of P. nitidus were found that have two marginal rimoportulae. Living cell of P. nitidus attached on sand grain solitary and it has many discoid plastids. The structures of rotae with fin-like projections in Psammodiscus differ from those of Rhaphoneidaceae genera. The epicingulum of Psammodiscus consists of three or four open bands with the valvocopula and second band opening at 180° to one another alternately at one apex.

Molecular phylogenetic analyses based on plastid-encoded rbcL and mitochondrial cox3 gene sequences, in combination with morphological observations, revealed the existence of the following four bistratose Padina species previously unreported from Australian coasts: Padina calcarea Ni-Ni-Win, S.G.A.Draisma, W.F.Prud'homme van Reine & H.Kawai, characterised by its bright yellow–orange inferior thallus surface and chalky white, heavily calcified superior surface, and the presence of hairlines only on the inferior surface; P. macrophylla Ni-Ni-Win, M.Uchimura & H.Kawai, characterised by a moderately calcified thallus with broad, depressed hairlines on the inferior surface and narrow, not depressed hairlines on the superior surface, those hairlines that are largely spaced on each surface; P. moffittiana I.A.Abbott & Huisman, characterised by lightly calcified thalli with narrow, slightly depressed hairlines that are distributed in alternate sequence between the two surfaces at unequal distances, and broad reproductive sori in one or two rows in the fertile zone; and P. okinawaensis Ni-Ni-Win, S.Arai, M.Uchimura & H.Kawai, characterised by heavily calcified thalli, except at the hairlines, which form an alternation of uncalcified furrows and calcified glabrous zones on the inferior surface. With the addition of these four species, 13 Padina species are known from Australia.