The genus was only erected in mid-2023 by four South American ichthyologists and their Swedish colleague Sven O. Kullander.

It was named in honour of the British naturalist Alfred Russel Wallace,[1] and is a near-tautonym of the chosen type species.

[3] The genus Wallaciia occurs in the Amazon Basin from the Rio Madeira to the Rio Tocantins, but is absent west of Santo Antônio do Içá or the mouth of the Río Putumayo into the Amazon.

With the exception of Wallaciia heckeli, the rear edge of the supracleithrum, a bone in the shoulder girdle, is serrated.

In contrast to the genus Saxatilia, Wallaciia lacks the humeral spot above the pectoral fin base.