Sphaeropleales

Hydrodictyaceae
Neochloridaceae
Scenedesmaceae
Selenastraceae
Sphaeropleaceae
The Sphaeropleales are an order of green algae. This order includes vegetatively nonmotile unicellular or colonial taxa that have biflagellate zoospores with flagella that are directly opposed in direction (the DO arrangement): Sphaeroplea , Atractomorpha , Neochloris , Hydrodictyon , and Pediastrum . All of these taxa have basal body core connections.

With an increase in the number of taxa for which sequence data are available, there is evidence of an expanded DO clade that includes additional zoosporic (Bracteacoccus , Schroederia ) and some strictly autosporic genera such as Ankistrodesmus , Scenedesmus , Selanastrum , Monoraphidium , and Pectodictyon

Monophyly of the DO clade is generally weakly supported by phylogenetic analysis of molecular data, even those that have used data from two genes

References

Lewis, L.A, McCourt, R.M. (2004) Green algae and the origin of land plants. AMERICAN JOURNAL OF BOTANY 91 (10): 1535-1556 OCT