The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of unicellular algae found in freshwater and moist terrestrial environments, less common today than they were during the Proterozoic. The stated number of species in the group varies from about 14 to 26. Together with the red algae (Rhodophyta) and the green algae plus land plants, they form the Archaeplastida.
Charales is an order of freshwater green algae in the division Charophyta, class Charophyceae, commonly known as stoneworts. Depending on the treatment of the genus Nitellopsis, living (extant) species are placed into either one family (Characeae) or two. Further families are used for fossil members of the order. Linnaeus established the genus Chara in 1753.
Sphaeropleales is an order of green algae that used to be called Chlorococcales. The order includes some of the most common freshwater planktonic algae such as Scenedesmus and Pediastrum. The Spaeropleales includes vegetatively non-motile unicellular or colonial taxa that have biflagellate zoospores with flagella that are directly opposed in direction : Sphaeroplea, Atractomorpha, Neochloris, Hydrodictyon, and Pediastrum. All of these taxa have basal body core connections.
The Fucales (fucoids) are an order in the brown algae. The list of families in the Fucales, as well as additional taxonomic information on algae, is publicly accessible at Algaebase.
Ectocarpales is a very large order in the brown algae. The order includes families with pseudoparenchymatous (Splachnidiaceae) or true parenchymatous (Scytosiphonaceae) tissue. Pseudoparenchymatous refers to a filamentous alga with cells packed very close together to give an appearance of parenchymatous tissue, the latter being composed of cells which can truly divide in three dimensions, unusual among the algae. Filamentous algae are composed of cells that divide along a single plane, allowing only elongation to form filaments of one or more rows of cells. Algae that can divide in two planes can form sheet-like thalli or bodies. Cells that can divide in a third plane potentially allow for the organism to develop a more complex body plan, and diversification of body plans into an erect thallus of some sort and a holdfast for attaching the upright portion to the substrate.
Ignatiaceae is a family of green algae in the class Ulvophyceae. It is the only family in the order Ignatiales.
Chlorocystidaceae is a family of green algae. It is the only family in the order Chlorocystidales. The family was formerly placed in the order Ulotrichales.
Monomastix is a genus of green algae in the class Mamiellophyceae. It is the only genus in the family Monomastigaceae, which in turn is the only family in the order Monomastigales.
Sykidion is a genus of green algae. Pseudoneochloris is a synonym of this genus. As of March 2022, Sykidion was the only genus in the family Sykidiacaeae, which was the only family in the order Sykidiales.
Chlorokybus is a multicellular (sarcinoid) genus of basal green algae or charophyte. It has been classified as the sole member of the family Chlorokybaceae, which is the sole member of the order Chlorokybales, in turn the sole member of the class Chlorokybophyceae. It grows on soil and rock surfaces, and is rare.
Mesostigma is a genus of unicellular biflagellate freshwater green algae, with a single species Mesostigma viride, covered by an outer layer of basket‐like scales instead of a cell wall. As of February 2022, AlgaeBase classified it as the only genus in the family Mesostigmataceae, the only family in the order Mesostigmatales, the only order in the class Mesostigmatophyceae. It is now considered to be one of the earliest diverging members of green plants/algae (Viridiplantae).
Coleochaetaceae is a family of algae. It is the only family in the Coleochaetales, an order of parenchymous charophyte algae, that includes some of the closest multicellular relatives of land plants. They questionably include the fossil genus Parka.
The Gymnodiniales are an order of dinoflagellates, of the class Dinophyceae. Members of the order are known as gymnodinioid or gymnodinoid. They are athecate, or lacking an armored exterior, and as a result are relatively difficult to study because specimens are easily damaged. Many species are part of the marine plankton and are of interest primarily due to being found in algal blooms. As a group the gymnodinioids have been described as "likely one of the least known groups of the open ocean phytoplankton."
Botrydiaceae is a family of yellow-green algae comprising 13 species in three genera. It is the only family in the order Botrydiales.
Onslowiaceae is the only family in order Onslowiales in the brown algae. The family contains only the genera Onslowia and Verosphacela.
Klebsormidiales is an order of charophyte algae. It is the only order in the class Klebsormidiophyceae, sister of the Phragmoplastophyta. As of February 2022, AlgaeBase accepted two families in the order:
Picophagea, also known as Synchromophyceae, is a class of photosynthetic stramenopiles. The chloroplast of the Synchromophyceae are surrounded by two membranes and arranged in a way where they share the outer pair of membranes. The entire chloroplast complex is surrounded by an additional two outer membranes.
Nephroselmidaceae is a family of green algae, the only family in the order Nephroselmidales and the class Nephrophyceae within the division Chlorophyta.
Syracosphaerales is an order of algae consisting of three families:
Rebecca is a genus of photosynthetic, flagellated marine haptophytes. It is one of four genera in the family Pavlovaceae. The holotype species, R. salina, was described in 2000 by J.C. Green; it is one of three species currently accepted in the genus. Also in the genus is R. helicata, which was described in the same publication as R. salina, and the third member is R. billiardiae, which was described in 2023. R. helicata and R. salina were both previously considered to be within the genus Pavlova.
