ISSN (print) 0868-8540, (online) 2413-5984
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Algologia 2012, 22(3): 227–249
General Problems of Algology

Chlorochytrium hypanicus sp. nov. (Chlorophyceae) and its position in the system of Protosiphonales

Kostikov I.Yu.1, Demchenko E.N.1, Boiko V.R.1, Goncharov A.A. 2

The description of a new species of green algae, Chlorochytrium hypanicus sp. nov. (Chlorophyceae), found in a flow of mud from the Southern Bug River (Ukraine) is presented. The analysis of the nucleotide sequence of the nuclear gene of 18S rDNA showed the position of this species in the system of Stephanosphaerinia macroclade, which generally corresponds to the previously proposed order Protosiphonales. It is shown that, in this order, incorporating four clades and "Protosiphonales incertae sedis" group of taxa, Chlorochytrium hypanicus, belongs to the clade corresponding Protosiphonaceae s.l., whose members differ from other representatives of this order by the presence of naked biflagellate zoospores. Morphologically, Ch. hypanicus is similar to Ch. lemnae Cohn, differing from it by anterior stigma in zoospores, thicker envelope of subsenile cells, a finely tuberculate envelope of akinetes, and by mode of life (free-living, not endophytic). From other species of the genus Chlorochytrium Cohn, new species differ by fission of desmoschisis type, leading to the formation of dyads, packages, and pleurococcal clusters. We discuss the volume, diacritical features, and structure of Protosiphonaceae, including the similarity of the results of molecular genetic and phenotypic approaches in the taxonomy of this family.

Keywords: green algae, taxonomy, molecular phylogeny, Chlorophyceae, Protosiphonales, Protosiphonaceae, Stephanosphaerinia, Chlorochytrium hypanicus.

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