The Roundworms (Nematoda) - phylum

(Monhysterida)
- order
(Dorylaimea) - class

(Rhabditida)
- order

(Trichinellida)
- order

(Mermithida)
- order
(Enoplea) - class

()

()

()

()
(Secernentea) - class

(Diplogasteria)
- subclass

(Rhabditia)
- subclass

(Spiruria)
- subclass

(Tylenchia)
- subclass
(Chromadorea) - class

()

()

()

()