SEM images of <i>Phycopeltis flabellata</i> and <i>P. prostrata</i>.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g005" target="_blank">Fig. 5A</a>. Adult thallus of <i>P. flabellata</i>. Bar = 500 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g005" target="_blank">Fig. 5B</a>. Sporangium of <i>P. flabellata</i>. Bar = 10 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g005" target="_blank">Fig. 5C</a>. Thallus of <i>P. prostrata</i> with erect hair. Bar = 100 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g005" target="_blank">Fig. 5D</a>. Sessile gametangia of <i>P. prostrata</i>. Bar = 40 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g005" target="_blank">Fig. 5E</a>. Partial thallus of sporophyte with sporangia. Bar = 100 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g005" target="_blank">Fig. 5F</a>. Sporangia of <i>P. prostrata</i>. Bar = 10 μm.</p

Development of the four species: <i>P. aurea</i>, <i>P. epiphyton P. flabellata</i>, and <i>P. prostrata</i>.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g003" target="_blank">Fig. 3A–3C</a>. Development of <i>P. aurea</i>. Bars = 10 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g003" target="_blank">Fig. 3D–3F</a>. Development of <i>P. epiphyton</i>. Bars = 10 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g003" target="_blank">Fig. 3G–3J</a>. Growth of <i>P. flabellata</i>. Bars for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g003" target="_blank">Fig. 3G</a>, 5 μm, for others, 10 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g003" target="_blank">Fig. 3K–3O</a>. Development of <i>P. prostrata</i>. Bars = 20 μm.</p

Key characters of species in present phylogram used to distinguish from other Trentepohliacean genera.

<p>Key characters of species in present phylogram used to distinguish from other Trentepohliacean genera.</p

Morphological Examination and Phylogenetic Analyses of <i>Phycopeltis</i> spp. (Trentepohliales, Ulvophyceae) from Tropical China

<div><p>During an investigation of Trentepohliales (Ulvophyceae) from tropical areas in China, four species of the genus <i>Phycopeltis</i> were identified: <i>Phycopeltis aurea</i>, <i>P. epiphyton</i>, <i>P. flabellata</i> and <i>P. prostrata</i>. The morphological characteristics of both young and adult thalli were observed and compared. Three species (<i>P. flabellata</i>, <i>P. aurea</i> and <i>P. epiphyton</i>) shared a symmetrical development with dichotomously branching vegetative cells during early stages; conversely, P. prostrata had dishevelled filaments with no dichotomously branching filaments and no symmetrical development. The adult thalli of the former three species shared common morphological characteristics, such as equally dichotomous filaments, absence of erect hair and gametangia formed in prostate vegetative filaments. Phylogenetic analyses based on SSU and ITS rDNA sequences showed that the three morphologically similar species were in a clade that was sister to a clade containing <i>T. umbrina</i> and <i>T. abietina</i>, thus confirming morphological monophyly. Conversely, <i>Phycopeltis prostrata</i>, a species with erect filaments, sessile gametangia on the basal erect hair, larger length/width ratio of vegetative cells and very loosely coalescent prostrate filaments, branched separately from the core <i>Phycopeltis</i> group and the <i>T. umbrina</i> and <i>T. abietina</i> clade. Based on morphological and molecular evidence, the genus <i>Phycopeltis</i> was paraphyletic. Furthermore, the traditional taxonomic criteria for <i>Phycopeltis</i> must be reassessed based on phylogeny using more species. A new circumscription of the <i>Phycopeltis</i> and the erection of new genera are recommended.</p></div

Morphological data of 25 <i>Phycopeltis</i> species from previous studies.

<p>Morphological data of 25 <i>Phycopeltis</i> species from previous studies.</p

Phylogram inferred from ML analysis of SSU rDNA sequences in the Trentepohliales (obtained with RAxML, ln(L) = -4975.4).

<p>Numbers indicate branches highly supported under all inference methods (>50% BP, >0.5 PP). The caldes of core <i>Trentepohlia</i>, <i>Cephaleuros</i>, <i>Printzina</i> and <i>Phycopeltis</i> were colored in red, green, blue and orange respectively. The previous <i>Phycopeltis</i> sequence (Genbank no. AY052570) was shaded in pink, the <i>Phycopeltis prostrata</i> was shaded in cyan and <i>Trentepohlia annulata</i> group were shaded in grey.</p

Microscopic features of <i>Phycopeltis aurea</i>, <i>Phycopeltis epiphyton</i> and <i>Phycopeltis flabellata</i>.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1A–1C</a>. Microscopic features of Phycopeltis aurea. Bars = 50 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1A</a>. Surface view of P. aurea. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1B</a>. Discoidal thallus with an even, crenate margin. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1C</a>. Intercalary sporangiate-laterals. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1D–1F</a>. Microscopic features of Phycopeltis epiphyton. Bars = 50 μm. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1D</a>. Surface view of the filaments of P. epiphyton. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1E</a>. Sporangiate-lateral (arrows) lying on the submarginal positions of discoid thalli. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1F</a>. Sporangiate-lateral developing from an apical cell on a compressed thallus (arrow). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114936#pone.0114936.g001" target="_blank">Fig. 1G</a>. P. flabellata consisting of compressed ramuli.</p

Micrographs of <i>Gymnodinium eucyaneum</i>.

<p><b>Figs. A–E.</b> Different cell shapes of the field samples. <b>F</b> Cells kept for 2∼4 weeks in the laboratory, showing that the chloroplast became smaller. <b>G</b> Ventral view showing the insertion of the flagella. <b>H, J, K</b> Ventral view showing the detail of the cingulum and sulcus. <b>I</b> Cysts each with a brownish accumulation of corpuscles. E: epicone; H: hypocone; N: nucleus; C: chloroplasts; CI: cingulum; S: sulcus; AC: accumulation of corpuscle. Scale bars: A–I = 10 μm; J–K = 2 μm.</p

Bayesian phylogenetic tree constructed from the nucleomorph SSU rDNA sequences.

<p>The numbers on the nodes represent the posterior probabilities (PP)/bootstrap support values (BP) produced by the Bayesian inference and maximum-likelihood analyses. Values >0.50 for PP and >50 for BP are shown. The sequences obtained in our study are shaded in gray.</p

Bayesian phylogenetic tree constructed from the chloroplast 23S rDNA sequences.

<p>The numbers on the nodes represent the posterior probabilities (PP)/bootstrap support values (BP) produce by the Bayesian inference and maximum-likelihood analyses. Values >0.50 for PP and >50 for BP are shown. The sequences obtained in our study are shaded in gray.</p