Ac
Actinarctus Schulz, 1935
- Actinarctus doryphorus Schulz, 1935
- Actinarctus lyrophorus Renaud-Mornant, 1979
- Actinarctus neretinus Grimaldi de Zio, D'Addabbo Gallo, Morone de Lucia, Vacoarella & Grimaldi, 1982
- Actinarctus physophorus Grimaldi de Zio, D'Addabbo Gallo, Morone de Lucia, Vacoarella & Grimaldi, 1982
Tardigrada → Heterotardigrada → Arthrotardigrada → Halechiniscidae
Acutuncus
- Acutuncus antarcticus (Richters, 1904)
Ad
Adorybiotus
- Adorybiotus granulatus (Richters, 1903)
Am
Amphibolus
- Amphibolus mahunkai (Iharos, 1971)
- Amphibolus markevichi Biserov, 1992
- Amphibolus nebulosus Dastych, 1983
- Amphibolus smreczynskii (Wêglarska, 1970)
- Amphibolus volubilis (Durante Pasa & Maucci, 1975)
- Amphibolus weglarskae (Dastych, 1972)
An
Angursa
- Angursa abyssalis Renaud-Mornant, 1981
- Angursa antarctica Villora, 1998
- Angursa bicuspis Pollock, 1979
- Angursa capsula Bussau, 1992
- Angursa clavifera Noda, 1985
- Angursa lanceolata Renaud-Mornant, 1981
- Angursa lingua Bussau, 1992
Tardigrada → Heterotardigrada → Arthrotardigrada → Halechiniscidae
Anisonyches
- Anisonyches deliquus Chang & Rho, 1998
- Anisonyches diakidius Pollock, 1975
- Anisonyches mauritianus Grimaldi de Zio, D'Addabbo Gallo, Morone de Lucia & Daddabbo Gallo, 1988
Tardigrada → Heterotardigrada → Echiniscoidea → Echiniscidae
Antechiniscus Kristensen, 1987
- Antechiniscus conversus (Horning & Schuster, 1983)
- Antechiniscus jermani Rossi & Claps, 1989
- Antechiniscus lateromamillatus (Ramazzotti, 1964)
- Antechiniscus moscali Claxton, 2001
- Antechiniscus parvisentus (Horning & Schuster, 1983)
- Antechiniscus perplexus (Horning & Schuster, 1983)
Tardigrada → Heterotardigrada → Echiniscoidea → Echiniscidae
Ap
Red Apochela Schuster, Nelson, Grigarick & Christenberry, 1980
- Porodica Milnesiidae Ramazzotti, 1962
Apodibius
- Apodibius confusus Dastych, 1983
- Apodibius nuntius Binda, 1986
- Apodibius richardi Vargha, 1995
Ar
Archechiniscus
- Archechiniscus marci Schulz, 1953
- Archechiniscus minutus Grimaldi-de-Zio & D'Addabbo Gallo, 1987
- Archechiniscus symbalanus Chang & Rho, 1998
Tardigrada → Heterotardigrada → Arthrotardigrada → Halechiniscidae
Red Arthrotardigrada Marcus, 1927
- Porodica Batillipedidae Riggin, 1962
- Porodica Coronarctidae Renaud-Mornant, 1974
- Porodica Halechiniscidae Thulin, 1928
- Porodica Renaudarctidae Kristensen & Higgins, 1984
- Porodica Stygarctidae Schulz, 1951
As
Astatumen
- Astatumen bartosi (Wêglarska, 1959)
- Astatumen ramazzotti (Iharos, 1966)
- Astatumen tamaensis (Sudzuki, 1975)
- Astatumen tamurai (Ito, 1990)
- Astatumen trinacriae (Arcidiacono, 1962)