Sphaeropleales

Sphaeropleales is an order of green algae that used to be called Chlorococcales.[2] The order includes some of the most common freshwater planktonic algae such as Scenedesmus and Pediastrum.[3] The Spaeropleales includes vegetatively non-motile 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.[2]

Sphaeropleales
Pediastrum duplex, an algae within the order Sphaeropleales
Scientific classification
(unranked):	Viridiplantae
Division:	Chlorophyta
Class:	Chlorophyceae
Order:	Sphaeropleales Luerssen
Families[1]
Bracteacoccaceae Bracteamorphaceae Characiaceae Chromochloridaceae Cylindrocapsaceae Dictyochloridaceae Dictyococcaceae Hydrodictyaceae Microsporaceae Mychonastaceae Neochloridaceae Nephrocytiaceae Pseudomuriellaceae Radiococcaceae Rotundellaceae Scenedesmaceae Schizochlamydaceae Schroederiaceae Selenastraceae Sphaeropleaceae Treubariaceae Tumidellaceae incertae sedis: Polyedriopsis

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, Selenastrum, and Monoraphidium. The filamentous Microspora has been allied with the coccoid genus Bracteacoccus based on molecular data.

Monophyly of the DO clade is supported by phylogenetic analysis of multi-gene data.[3][4]