There are roughly 150 known Lactifluus species, which have a mainly tropical distribution but are also found in the north temperate zone and Australasia.

[3] In the following, the name Lactarius was conserved for the biggest of the subclades revealed, containing most well-known north temperate species.

[9][10][11] A phylogenetics-based revision in 2017 divided the genus in four subgenera: Lactifluus, Lactariopsis, Gymnocarpi and Pseudogymnocarpi.

[2] Lactifluus closely resembles its lookalike genus Lactarius, with whom it shares the brittle flesh of the fruit bodies and the milk-like latex exuded when bruised.

[8] Microscopically, thick-walled elements in the pileipellis and stipitipellis (cuticle of the stipe) and sphaerocytes in the trama of the lamellae are common in Lactifluus, but rare in Lactarius species.