Studies of the green algaPercursaria dawsonii(=Blidingia dawsoniicomb. nov., Kornmanniaceae, Ulvales) in British Columbia

Abstract

SUMMARY We cultured and sequenced newly collected material of Percursaria dawsonii Hollenberg et I. A. Abbott, a poorly known epibiont of limpets found along the west coast of North America. Zoospores, parthenogametes, and zygotes exhibited empty‐spore germination, which produced a prostrate system that expanded by stolon‐like development. A dense carpet of initially uniseriate filaments arose from the prostrate system. These upright filaments soon became biseriate proximally and pluriseriate distally, where they were flat, twisted and distromatic for approximately four‐fifths of their length and rarely became hollow in larger individuals. These fronds became fertile distally and released quadriflagellate zoospores and/or biflagellate isogametes. Individual gametophytic fronds were dioecious, and alternated with isomorphic sporophytic fronds. The gametes moved rapidly and often exhibited an unusual side‐to‐side vibration that made them appear like winged insects. Comparisons of 18S rRNA gene and ITS sequences indicated that P. dawsonii should be included in the genus Blidingia, family Kornmanniaceae.

A close-up view on ITS2 evolution and speciation - a case study in the Ulvophyceae (Chlorophyta, Viridiplantae)

“…So far, the ITS2 molecule has only rarely been used as marker for phylogenetic analyses in the Ulvales, except in studies of single genera ( Acrochaete - [ 77 ]; Acrosiphonia - [ 78 ]; Blidingia - [e.g. [ 79 , 80 ]]; Collinsiella / Monostroma - [ 81 ]; Gloeotilopsis - [ 82 ]; Ulva - [e.g. [ 23 , 83 - 88 ]]; Ulvaria - [ 89 ]; Urospora - [ 90 ].…”

Life History and Systematic Studies of Pseudothrix borealis gen. et sp. nov. (=North Pacific Capsosiphon groenlandicus, Ulotrichaceae, Chlorophyta)

“…The germination of the zygote appears to start by empty-spore formation and production of a short germ-tube, which continues to grow through internal incremental depositions of the advancing protoplast. The early stage resembles empty-spore germination in Blidingia (Bliding 1963) as well as the formation of stoloniferous cells from prostrate discs of some Blidingia taxa (Garbary and Tam 1989;Lindstrom et al 2006). The function of empty-spore germination is unknown, but its occurrence in brown and red as well as green algae suggests it is important.…”

Phylogeny and Molecular Evolution of the Green Algae

“…Molecular phylogenetic studies provide poor or no support for the separation of the orders (e.g., O'Kelly et al, 2004a;O'Kelly et al, 2004c). Diversity and phylogenetic relationships within the clade have been studied based on plastid genes (mainly rbcL) and nuclear 18S sequence data (Hayden & Waaland, 2002;Hayden & Waaland, 2004;O'Kelly et al, 2004a;O'Kelly et al, 2004c;O'Kelly et al, 2004b;Lindstrom & Hanic, 2005;Lindstrom et al, 2006;Loughnane et al, 2008;Heesch et al, 2009;Kraft et al, 2010;O'Kelly et al, 2010). The relationships of unicellular or sarcinoid members (e.g., Desmochloris, Halochlorococcum, Pseudoneochloris) may provide important insights into the evolution of multicellularity in the clade, but as yet, their phylogenetic positions are poorly resolved (Watanabe et al, 2001;O'Kelly et al, 2004a;O'Kelly et al, 2004c).…”