Studies on Ultrastructure and Three-Gene Phylogeny of the Genus Mallomonas (Synurophyceae)1

Abstract

The genus Mallomonas, a common and often abundant member of the planktic community in many freshwater habitats worldwide, consists of 180 species divided into 19 sections and 23 series. Classification of species is based largely on ultrastructural characteristics of the siliceous scales and bristles that collectively form a highly organized covering over the cell. However, the relative importance of the different siliceous features of the scales, such as the dome, V rib, and secondary structures, as well as the different types of scales, in understanding the evolution and phylogeny of the genus is little known. In this study, we investigated the scale and bristle ultrastructure, along with sequences of three genes, for 19 isolates (18 species) of Mallomonas (18 isolates were from Korean habitats). The isolates represented nine of the 19 sections. Sequences for both the nuclear SSU and LSU rDNA and plastid LSU of RUBISCO (rbcL) genes for each of the 19 Mallomonas isolates and four outgroups were determined. Bayesian and maximum-likelihood (ML) analyses of the data revealed that Mallomonas consists of two strongly supported clades. Mallomonas bangladeshica (E. Takah. et T. Hayak.) Siver et A. P. Wolfe was at the base of the first clade that included taxa from the sections Planae and Heterospinae, both of which lack a V rib on the shield of the scales. Our results indicated that the sections Planae and Heterospinae should be combined. The second clade, with Mallomonas insignis Penard and Mallomonas punctifera Korshikov at the base, contained taxa from the sections Mallomonas, Striatae, Akrokomae, Annulatae, Torquatae, Punctiferae, and Insignes, all of which have V ribs or well-developed marginal ribs on the scales. Sister relationships between Mallomonas and Striatae were strongly supported, but interrelations among the remaining sections were not resolved, probably due to inclusion of too few species. Our results suggest that the current classification of the genus Mallomonas at the section level will require some revision. Additional species will need to be added in future analyses.

Morphological delineation and distribution patterns of four newly described species within theSynura peterseniispecies complex (Chrysophyceae, Stramenopiles)

“…The amplification of ITS rDNA was performed as described in Kynčlová et al (2010), using the primers Kn1.1 (5ʹ-CAA GGT TTC CGT AGG TGA ACC-3ʹ; Wee et al, 2001) and ITS4 (5ʹ-TCC TCC GCT TAT TGA TAT GC-3ʹ; White et al, 1990). Amplification of the rbcL marker was performed according to Jo et al (2011), using the primers rbcL_2F (5ʹ-AAA AGT GAC CGT TAT GAATC-3ʹ; Daugbjerg & Andersen, 1997) and rbcL_R3 (5ʹ-GTA ATA TCT TTC TTC CAT AAA TCT AA-3ʹ; Jo et al, 2011). The cox1 marker was amplified according to Boo et al (2010), using the primers F692 (5ʹ-TTG TDT GGT CAG TTT TAA TTA C-3ʹ) and R1433 (5ʹ-GGC ATA CCT GCW ARA CCT AA-3ʹ; Boo et al, 2010).…”

Chrysodidymus Prowse (Chrysophyceae, Synurales), a new genus for the Ukrainian algal flora

“…synuroideus», обитающего в тропических и субтропических широтах, имеют более узкий загнутый край, лишенный перфораций, а поры базальной пластины окружены 5-6 гранулами (Hansen, 1996;Vigna, Siver, 2003;Siver, Lott, 2006;Gusev, 2013). Последний признак особенно важен в систематике рода Mallomonas M. Perty (Gusev, 2013;Jo et al, 2013) и странно, что до сих пор никто не обращал внимания на подобные различия у Chrysodidymus. К сожалению, в единственной работе, посвященной чешуйчатым золотистым водорослям Малайзии (Dürrschmidt, Croome, 1985), приводится только электронно-микроскопическая фотография всей колонии Ch.…”

Synurophyte Algae**This chapter is dedicated to my mother, Helen Jean Siver. THANKS, MOM.

“…In their monograph on Mallomonas, Asmund and Kristiansen (1986), and later Kristiansen (2002), considered species with scales that lacked domes and secondary structures, that had smooth and bifurcate bristles, and that had cells with two emergent flagella as ancestral. Mallomonas bangladeshica (Takahashi & Hayakawa) Nicholls diverged at the base of the clade lacking V-ribs, and M. insignis at the base of the clade with a V-rib (Jo et al, 2011. Based on a three-gene dataset, Jo et al (2011) demonstrated that Mallomonas is divided into two major clades based, in part, on the presence or absence of a V-rib and that this divergence occurred in the Early Cretaceous .…”