[in French with additional abstract in Esperanto and English: ] Morpho–anatomical description and chemistry of Leprocaulon pseudocalcicola Cl. Roux et Magain sp. nov., close to but distinct from L. calcicola. Phylogenetic tree of the Leprocaulon known worldwide, based on the ITS and mtSSU loci. Key to the determination of the Leprocaulon of Europe.