1. Subfamily Steinmanellinae M. R. Cooper, 1991 †
   1. Genus Garatella M. R. Cooper & H. A. Leanza, 2017 †
   2. Genus Neuquenella M. R. Cooper & H. A. Leanza, 2017 †
   3. Genus Philippiella M. R. Cooper & H. A. Leanza, 2017 † (accepted > unreplaced junior homonym, junior homonym of Philippiella Pfeffer, 1886 [Bivalvia: Philobryidae] and Philippiella Poulsen, 1965 [Ostracoda])
   4. Genus Pseudoyaadia M. R. Cooper & H. A. Leanza, 2017 †
   5. Genus Splenditrigonia H. A. Leanza, 1993 †
   6. Genus Steinmanella Crickmay, 1930 †
   7. Genus Stoyanowella M. R. Cooper & H. A. Leanza, 2017 †
   8. Genus Transitrigonia Dietrich, 1933 †
   9. Genus Weaverella M. R. Cooper & H. A. Leanza, 2017 †
   10. Genus Macrotrigonia H. H. Camacho & Olivero, 1985 † accepted as Transitrigonia Dietrich, 1933 † (unaccepted > junior subjective synonym)
   11. Genus Steinmanaea Crickmay, 1962 † accepted as Steinmanella Crickmay, 1930 † (unaccepted > junior objective synonym, unnecessary replacement name for Steinmanella Crickmay, 1930, non Steinmannella Welter, 1911 [Calcarea])
2. Subfamily Yaadiinae M. R. Cooper & H. A. Leanza, 2017 †
   1. Genus Louella M. R. Cooper & H. A. Leanza, 2017 †
   2. Genus Popenoella M. R. Cooper & H. A. Leanza, 2017 †
   3. Genus Tashiroella M. R. Cooper & H. A. Leanza, 2017 †
   4. Genus Yaadia Crickmay, 1930 †
   5. Genus Yeharella T. Kobayashi & Amano, 1955 †
   6. Genus Packardella T. Kobayashi & Amano, 1955 † (unaccepted > nomen nudum, no type species designated)
   7. Genus Setotrigonia T. Kobayashi & Amano, 1955 † accepted as Yeharella T. Kobayashi & Amano, 1955 † (unaccepted > junior subjective synonym)

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