Excavate

The excavates are a group of flagellate protozoa, including both free-living and symbiotic forms, some of which are important parasites. They typically have two or more flagella inserted at the anterior of a ventral feeding groove supported by microtubules. Some have mitochondria with discoid cristae, but many lack them entirely. The following lines are included here:

• Retortamonads[?]
• Diplomonads[?]
• Malawimonas[?]
• Trimastix[?]
• Carpediemonas[?]
• Jakobids[?]
• Heterolobosea

The relationship between these groups has only recently been recognised, largely because amitochondriate flagellates (roughly Archezoa) were considered basal and unrelated to mitochondriate lines. There is still the possibility that the excavates are paraphyletic to the other eukaryotes, and more work will need to be done before their exact position is clear.