SSU rRNA GENE PHYLOGENY OF MORPHOSPECIES AFFILIATED TO THE BIOASSAY ALGA “SELENASTRUM CAPRICORNUTUM” RECOVERED THE POLYPHYLETIC ORIGIN OF CRESCENT-SHAPED CHLOROPHYTA1

Abstract

The generic concept of coccoid green algae exhibiting a crescent-shaped morphotype is evaluated using SSU rRNA gene sequence analyses and light and electron microscopical observations. These common chlorophytes evolved polyphyletically in 10 different clades of the Chlorophyceae and three clades of the Trebouxiophyceae. Six clades are assigned to known genera of Selenastraceae: Kirchneriella, Nephrochlamys, Raphidocelis, Rhombocystis, Selenastrum, and Tetranephris. Four other clades, named following their present genus designation as Ankistrodesmus-like I and II and Monoraphidium-like I and II, require further investigation. One crescent-shaped morphotype, which evolved within the Trebouxiophyceae, is designated as Neocystis mucosa sp. nov. The other two lineages containing trebouxiophycean algae with this morphotype are the Elliptochloris and the Watanabea clades. The taxonomic placement of the widely used bioassay strain "Selenastrum capricornutum" NIVA-CHL 1 in the genus Raphidocelis (species name Raphidocelis subcapitata) is indicated by molecular data.

Strain survey on three continents confirms the polyphyly of the genus Pediastrum (Hydrodictyaceae, Chlorophyceae).

“…. In Selenastraceae similar phenotypes such as the needle-shaped or crescent-shaped morphology hide a multitude of phylotypes (FaWLey et al 2007;krienitz et al 2011). In the Hydrodictyaceae members of the genus Pseudopediastrum are characterized both by high morphological diversity and phylogenetic divergence resulting in four new combinations in this study.…”

“…Total Genomic DNA was extracted according to krienitz et al (2012). The 18S rRNA and ITS-2 rRNA genes were amplified and sequenced as described by Bock et al (2011) LeWis (2005. Scenedesmus obliquus UTEX 393 was selected as outgroup.…”

Algas planctônicas flageladas e cocoides verdes de um lago no Parque Beija-Flor, Goiânia, GO, Brasil

“…Krienitz et al (2011b) indicaram a tendência da proximidade das características morfológica entre as espécies de S. rinoi, S. bribraianum e S. gracile. Estes autores consideraram necessário um estudo mais acurado de biologia molecular para delimitar a posição diagnóstica destes táxons.…”

“…Kostikov et al (2002). A literatura utilizada na identificação de morfoespécies de algas cocoides foi: Komárek & Fott (1983), Komárek (1983), Comas (1996), Hindák (1984Hindák ( , 1988Hindák ( , 1990; Ettl (1983), com as devidas atualizações por Bock et al (2010), Hegewald et al (2010), Krienitz et al (2011aKrienitz et al ( , 2011b e Bock et al (2013).…”

Sediment biotesting in the Baltic Sea

“…*Pseudokirchneriella subcapitata is currently regarded as a synonym of Raphidocelis subcapitata. R. subcapitata is currently the accepted name for the type species (Krienitz et al, 2011) and therefore it is the most appropriate one for this species. However, considering that in ecotoxicology the use of the name P. subcapitata is more general than R. subcapitata, we chose to use it here.…”