Mostly they are known from members of the Gigasporaceae. Currently this family contains Gigaspora, Scutellospora and Racocetra, but there are other generic names that have not been widely accepted (Dentiscutata, Cetraspora, Fuscutata and Quatunica) — all of these form auxiliary cells. Members of the genus Pacispora (another genus in the Diversisporales) are also said to produce a kind of auxiliary cell but this requires further confirmation.
The Gigasporaceae family is known for its members, including Gigaspora, Scutellospora, and Racocetra. Other less widely accepted names like Dentiscutata, Cetraspora, Fuscutata, and Quatunica also form auxiliary cells.  There's some evidence that the genus Pacispora in Diversisporales may produce a similar auxiliary cell, but this needs further verification.