The South American tribe Echinopsideae (a new name for Trichocereae) of the Cactaceae, together with its sub-tribe Echinopsidinae, are briefly described. Trichocereus is once again united with Echinopsis. The enlarged genus Echinopsis is sub-divided into 3 sub-genera: Trichocereus, Echinopsis and Acanthocalycium. Soehrensia forms a section of Trichocereus, with Lobivia grand/flora as a transitional species. The Aurea group (Sect. Pseudoechinopsis) belongs to the sub-genus Echinopsis, with Hymenorebulia deriving from it. In phylogenetic terms, and on the basis of seed-type, Reicheocactus pseudoreicheanus BACKBG. could be included here. Lobivia arachnacantha with its var. torrecillasensis, Lobivia cardenasiana and Lobivia fricii clearly belong to Echinopsis, Sect. Echinopsis.
The origin of Lobivia is quite distinct, the occasional spiny areoles found on the fruit of some species as well as the very archaic flower-structure excluding any development from Tricho-cereus-Echinopsis; on the contrary, it is closely related to the ancestors of the entire tribe.
Given this line of development, the genus divides up quite naturally as follows: Acanlholo-bivia as subgenusprimitivum, with its sections Acantholobivia and Boreolobivia (nom.nov.); and deriving from this, as sub-genera, Furiolobivia and Lobivia.
Because of its origin and characteristics, the last named is dubious, since it exhibits characteristics combining both the ancestral Lobivia and Echinopsis. The hypothesis of a hybrid origin: Acantholobivia x Echinopsis is now offered.
Rebutia (including Mediolobiviamd Aylosiera)cannot derive from Lobivia in the sense now clarified, but perhaps from Hymenorebutia. However the author considers some segregated status to be more probable. The phylogenetic tree at the close of the paper has been constructed on the basis of this theory.