Phylogenetic position of Koliella (Chlorophyta) as inferred from nuclear and chloroplast small subunit rDNA

The phylogenetic position of Koliella, a chlorophyte characterized by Klebs ormidium type cell division, was inferred from analyses of partial 18S rDNA and partial 16S rDNA, Parsimony and distance analyses of separate and comb ined data sets indicated that the members of Koliella belonged to Trebouxio phyceae, and high decay indices and bootstrap values supported this affinit y, However, the genus appeared to be polyphyletic, Koliella spiculiformis, the nomenclatural type of the genus, was allied with Nannochloris eucaryota and the "true" chlorellas (Chlorella vulgaris, C, lobophora, C. sorokinian a, and C, kessleri), The close relatives of Koliella longiseta (equivalent to Raphidonema longiseta) and Koliella sempervirens appeared to be Stichoco ccus bacillaris and some species traditionally classified in Chlorella that were characterized by the production of secondary carotenoids under nitrog en-deficient conditions. This clade was also supported by the presence of a relatively phylogenetically stable group I intron (1506) in the 18S rRNA g ene. Because of the presence of Klebsormidium type cell division, some auth ors regarded the members of Koliella as closely related to charophytes, Mol ecular analyses, however, did not confirm this affinity and suggested that a Klebsormidium type cell division is homoplastic in green plants.