Cyanidium caldarium in the Tree of Life

Domain->Eukaryota   
Kingdom-> Protista
Phylum-> Rhodophyta  
Class -> Rhodophyceae
Order-> Cyanidiales        
Family-> Cyanidiaceae       
Genus-> Cyanidium
Species->caldarium

Cyanidium caldarium is classified as a eukaryote because it contains a true nucleus and membrane bound organelles.

The kingdom Protista is essentially a dumping ground for organisms that do not fit into any of the other kingdoms

Cyanidium caldarium is classified as a member of the rhodophyta because it lacks flagella and because it contains the photosynthetic pigments, phycoerythrin and phycocyanin.

Rhodophyceae is the sole class of the phylum, rhodophyta

Cyanidium caldarium is classified as a member of the cyanidiales because it is asexual, unicellular and has the ability to grow in hot and acidic environments.  This order contains three genera.  These genera are Cyanidium, Galdieria, and Cyanidioschyzon.  Galdiera Sulphurarous will soon be the first of the cyanidiales to have its genome sequenced.

Cyanidiaceae is the sole family of the order, cyanidiales.

Cyanidium is separated from the other cyanidiales based on genetic data.

Cyanidium caldarium is the sole species of the genus Cyanidium.  Its name refers to its blue-green color and its habitat of hot streams and soils.

The cyanidiales are differentiated from each other based on molecular evidence.  Specifically, the genes psaA, psaB, and rbcL have been used to differentiate them.

Using the supergroup system of classification, Cyanidium caldarium and other red algae are part of the supergroup, archaeplastida, which also includes green algae and land plants.  All members of the archaeplastida are photosynthetic.