Lactifluus
Lactifluus is one of three genera of mushroom-forming fungi containing species commonly named "milk-caps", the others being "Lactarius" and "Multifurca". It has been separated from "Lactarius" based on molecular phylogenetic evidence but is very similar to that genus. There are roughly 150 known "Lactifluus" species, which have a mainly tropical distribution but are also found in the north temperate zone and Australasia. Some of them are edible mushrooms. Systematics and taxonomy. The genus "Lactifluus" was described in 1806 by French naturalist Henri François Anne de Roussel, with the type species "Lactifluus piperatus". Later, "Lactifluus" was largely considered  a synonym of "Lactarius", until molecular phylogenetic work showed in 2008 that "Lactarius" was not a monophyletic group. In the following, the name "Lactarius" was conserved for the biggest of the subclades revealed, containing most well-known north temperate species. Thus, the name "Lactifluus" could be used for the smaller genus, necessitating only a few name changes, as combinations with "Lactifluus" had already been made previously for many temperate species. New combinations have since been proposed for several species formerly classified in "Lactarius". A phylogenetics-based revision in 2017 divided the genus in four subgenera: "Lactifluus", "Lactariopsis", "Gymnocarpi" and "Pseudogymnocarpi . They are further subdivided into section, but not all species are assigned to named sections. Many of these new groups do not correspond to previous subdivisions based mainly on morphology. Selected species. , there are roughly 150 described species, classified in four subgenera. Some notable species are listed below under their respective subgenera. Description. 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. So far, synapomorphic characters for the genus have not been discovered, there are only tendencies that distinguish it from "Lactarius". Pleurotoid  (laterally stiped) fruitbodies are only known in "Lactifluus", while species with closed (angiocarpous) fruitbodies only occur in "Lactarius". 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. Edibility. Several species in the genus are edible. "Lactifluus volemus" especially is a choice mushroom in the northern temperate region.