Multigene phylogeny of <i>Synura</i> (Synurophyceae) and descriptions of four new species based on morphological and DNA evidence

<p>We used phylogenetic analyses based on multiple gene sequences (partial nr SSU and LSU rDNA, partial pt LSU rDNA, <i>psa</i>A and <i>rbc</i>L) from 148 strains (including three outgroups) and scale ultrastructure to examine phylogenetic relationships among species of the colonial genera <i>Synura</i> and <i>Tessellaria</i>. The phylogenetic tree based on the combined dataset was congruent with ultrastructural characteristics of the scales. <i>Synura</i> was divided into three major clades, two including species in section <i>Synura</i>, and one representing section <i>Peterseniae</i>. One clade, consisting of seven strains of <i>S. uvella</i> (section <i>Synura</i>), diverged at the base of the genus. The second clade consisted of the remaining species belonging to the section <i>Synura</i>. The third clade, containing organisms in the section <i>Peterseniae</i> and characterized by scales possessing a keel, was monophyletic with strong support values. Based on our findings, <i>S. uvella</i> needs to be in a separate section from other spine-bearing species, and we therefore propose new sectional ranks; <i>Synura, Peterseniae, Curtispinae</i> (presence of body scales with slender spines, tubular scales and caudal scales). We further propose four new species based on phylogenetic analyses and unique scale characters: <i>S. longitubularis</i> sp. nov., <i>S. sungminbooi</i> sp. nov., <i>S. soroconopea</i> sp. nov. and <i>S. lanceolata</i> sp. nov. Lastly, we propose a new genus name, <i>Neotessella</i>, to replace the invalid use of the name <i>Tessellaria</i>.</p

Fig2 Time-calibrated phylogenetic tree.tre

Figure 2. Time-calibrated phylogenetic tree for the Synurophyceae based on a five-gene dataset

Fig2 Five gene data matrix.nex

Five gene data set (nuclear SSU, nuclear LSU, plastid LSU, plastid psaA, plastid rbcL