After Martin & Davis, 2001

<==o Harpacticoida Sars, 1903 (ryömijähankajalkaiset)
   |-- Adenopleurellidae Huys, 1990
   |-- Aegisthidae Giesbrecht, 1893
   |-- Ambunguipedidae Huys, 1990
   |-- Ameiridae Monard, 1927
   |-- Ancorabolidae Sars, 1909
   |-- Argestidae Por, 1986
   |-- Balenophilidae Sars, 1910
   |-- Cancrincolidae Fiers, 1990
   |-- Canthocamptidae Sars, 1906
   |-- Canuellidae Lang, 1944
   |-- Cerviniidae Sars, 1903
   |-- Chappuisiidae Chappuis, 1940
   |-- Cletodidae Scott, 1905
   |-- Cletopsyllidae Huys & Williams, 1989 [Normanellidae: Cletopsyllinae]
   |-- Clytemnestridae Scott, 1909
   |-- Cristacoxidae Huys, 1990
   |-- Cylindropsyllidae Sars, 1909
   |-- Darcythompsoniidae Lang, 1936
   |-- Diosaccidae Sars, 1906
   |-- Ectinosomitidae Sars, 1903
   |-- Euterpinidae Brian, 1921
   |-- Hamondiidae Huys, 1990
   |-- Harpacticidae Dana, 1846
   |-- Huntemanniidae Por, 1986
   |-- Laophontidae Scott, 1905
   |-- Laophontopsidae Huys & Willems, 1989 [Namakosiramiidae]
   |-- Latiremidae Bozic, 1969
   |-- Leptastacidae Lang, 1948 [Pseudotachidiidae: Leptastacinae]
   |-- Leptopontiidae Lang, 1948 [Cylindropsyllidae: Leptopontiinae]
   |-- Longipediidae Sars, 1903
   |-- Louriniidae Monard, 1927
   |-- Metidae Sars, 1910
   |-- Miracidae Dana, 1846
   |-- Neobradyidae Oloffson, 1917
   |-- Normanellidae Lang, 1944
   |-- Novocriniidae Huys & Iliffe, 1998
   |-- Orthopsyllidae Huys, 1990
   |-- Paramesochridae Lang, 1944
   |-- Parastenheliidae Lang, 1936
   |-- Parastenocarididae Chappuis, 1933
   |-- Peltidiidae Sars, 1914
   |-- Phyllognathopodidae Gurney, 1932
   |-- Porcellidiidae Boeck, 1865
   |?- Pseudopeltidiidae [not recognized by Martin & Davis, 2001]
   |--o Pseudotachidiidae Lang, 1936 [Thalestridae: Pseudotachidiinae]
   |  `-- Paranannopinae Por, 1986 sensu Willem 1999 [Paranannopidae Por, 1986; Danielsseniidae Huys et al., 1996]
   |-- Rhizothricidae Por, 1986
   |-- Rotundiclipeidae Huys, 1988
   |-- Styracothoracidae Huys, 1993
   |-- Superornatiremidae Huys, 1997
   |-- Tachidiidae Boeck, 1865
   |-- Tegastidae Sars, 1904
   |-- Tetragonicipitidae Lang, 1944
   |-- Thalestridae Sars, 1905
   |-- Thompsonulidae Lang, 1944
   `-- Tisbidae Stebbing, 1910

Reference(s):