It is possible that a carpometacarpus bone apparently of an Aythya diving duck is referrable to these canards.

Earlier, it was proposed that Meller's duck, also from Madagascar, is the closest living relative of A. theodori, but as more remains of the latter were unearthed this appears far less likely.

Bones have been found in the Mare aux Songes swamp on Mauritius and more recently on Réunion also.

The scientific name honours Théodore Sauzier [de], who made many bones of extinct birds found on Mauritius available to science.

On Réunion, the species is last mentioned to occur "in quantity" in de la Merveille's 1709 listing of the island's wildlife, but as Jean Feuilley had not listed waterfowl in his 1705 report, de la Merveille's record is obviously based on obsolete hearsay information.