Outline of the classification of European Russula according to Romagnesi (1987, Les Russules)
Subgenus Compacta (Fr.) Bon
Mostly large species with enrolled cap margin, firm, compact flesh, short and thick stipe and unequal gills with lamellulae of different lengths. Pileipellis composed of slender hyphal extremities, generally with some lactiferous or 1 (-2)-celled dermatocystidia. Pigment, when present, brown, diffuse and vacuolar.
Type species: R. nigricans.
Sections: Archaeinae Heim: Romagn., Nigricantinae Bataille, Plorantinae Bataille
Subgenus Heterophyllidia Romagn.
Taste mild or nearly so, except in gills of some species. Spores white to cream, exceptionally pale ochre. DC present, except in Virescentinae and Amoeninae, unicellular. Without primordial hyphae, but with typical multiseptate often subulate hyphal extremities, containing mostly a granular pigment. Red pigments absent except in Amoeninae.
Type species: R. grisea.
Sections: Indolentinae Mlz. & Zv., Heterophyllinae Maire, Ilicinae Romagn., Griseinae J.Schaef., Virescentinae Sing., Amoeninae Sing.
Subgenus Ingratula Romagn.
Taste generally very acrid or nauseous, rarely mild. Smell frequently disagreeable. Cap mostly developing a striate margin, viscid when humid. Spores white to cream. DC present but often inconspicuous. Stipe strongly lacunose. Ochraceous to brown pigments, sometimes encrusting.
Type species: R. foetens
Sections: Foetentinae Mlz. & Zv., Felleinae Mlz. & Zv.
Subgenus Russula Romagn.
Taste more or less acrid, or menthol-like or bitter, exceptionally mild or nearly so. Spore print white, cream, rarely ochraceous. DC present, septate or not, morphologically well characterized, strongly reacting to sulphoaldehydes or more or less acidoresistant. Pigments red, purple, lila, more rarely green or yellow, never encrusting.
Type species: R. emetica
1. Piperinae-rubroflavae: Cap bright red or yellow, stipe usually white.
Sections: Lepidinae Mlz. & Zv., Rubrinae Sing. ss. str., Emeticinae Mlz. & Zv. ss. str., Persicinae Romagn., Citrinae (Romagn.) Bon
2. Piperinae-variecolores: Cap rarely bright red, stipe often more or less concolorous. Gills often more or less decurrent. Ectomycorrhizal with conifers
Sections: Atropurpurinae Romagn., Violacinae Romagn., Exalbicantinae Sing., Sardoninae Sing.
Subgenus Incrustatula Romagn.
Taste mild. DC absent. Pellis with primordial hyphae, and either pseudoparenchymatic or with apically inflated terminal cells or without lactifers in stipe. Spore print white, cream or yellow, rarely ochraceous.
Type species: R. lilacea
Sections :Roseinae Sing., Lilaceinae Mlz. & Zv. ss. str.
Sections: Amethystinae Romagn., Chamaeleontinae (Sing.) emend. Romagn., Ochroleucinae Romagn. (1985)
Subgenus Tenellula Romagn.
Completely mild or moderately acrid in gills or when very young. Mostly small, slender species with striate margin and fragile, frequently subclavate stipe. Pileipellis easily separable, viscose, with pluriseptate DC and poorly differentiated hyphal extremities. Lactifers in subpellis and stipe. Spore print cream, ochre to yellow. Basidia typically short and cystidia few and usually also short. Context often yellowing.
Type species: R. puellaris.
Sections: Puellarinae Sing., Rhodellinae Romagn., Sphagnophilinae Sing., Laricinae Romagn.
Subgenus Polychromidia Romagn.
Taste mild or slightly acrid in young gills. Context rather firm, never blackening, often distinctly yellowing or browning instead. Pellis composition very variable, DC or primordial hyphae can be present or lacking. Cap rarely red or orange, mostly violet, purple, green, brown to ochraceous. Voluminous but relatively short basidia . Long and broad cystidia.
Type species: R. integra.
Sections: Melliolentinae Sing., Viridantinae Mlz. & Zv., Integroidinae Romagn., Olivaceinae Sing. ss. str.,, Integrinae Maire ss. str.
Subgenus Coccinula Romagn. (1987)
Taste mild. Spore print ochre to yellow, exceptionally white. Relatively large and robust. Context not changing colour or turning vaguely reddish brown or gray to black. Smell not fishy nor sweet. Cap reddish, orange or yellowish, rarely whitish or lila. Lactifers or DC distinct at least in the stipe outer layer. Primordial hyphae rarely present.
Sections: Decolorantinae Maire ss. str., Paludosinae Schaef., Laetinae Romagn.
Subgenus Insidiosula Romagn.
Taste mostly acrid to very acrid. Spore print yellow. Relatively large and robust. Stipe generally white or with reddish tints. Gills obtuse near margin. DC always present and sulphoaldehyde sensitive. Basidia and cystidia not remarkably short.
Type: R. veternosa
Sections: Urentinae Maire ss. str., Maculatinae Konr. & Joss.
This subdivision corresponds exactly to the one Romagnesi presented in 1967 and 1985, except for the fact that all former supersections are transferred to subgeneric level. In comparison with earlier classifications of European Russula, the microscopic features have gained much importance in the principal subdivision of the genus, particularly the composition and different elements of the pellis, size of basidia and cystidia.