My personal attitude to a Cactaceae taxonomy
Protrusion on caucus Moscow cacti club under the book by A. Anderson "Cactus family"
translation from Russian by Vsevolod Goloviznin (Sevastopol, Urkaine)
The question is relevant and very difficult. Unfortunately (but may be vice versa), there is no official international agency in botany which could affirm or not affirm new suggestions about classification. That is why what to choose is amateur's personal business. As for me, I rely on my own unconscious sensations that are being formed during reading different cactus magazines (American, English and German ones) and some stuff from the Internet. Of course at the heart of my opinion lies Backerberg.
Here is shortened history of contemporary cactus taxonomy by A. Anderson and his book "Cactus family". In the six-volume "Cacti", published in 1958-1962, Backerberg gives the description of 220 stems and almost 3000 species. "Cactus Lexicon", published in 1976, made Backerberg's classification extremely popular among amateurs and commercials. However, as Hunt wrights: "… he named 78 stems and named or renamed 1200 species and even did not create herbarium samples or refer to them". Also we should understand that the book was published more than 40 years ago. During these 40 years numerous researches were done, many new species and even stems were discovered, new methods of researching (scanning electrical microscopy, DNA analyses) appeared. That is why mutual relations between species and stems have become clearer.
Almost at the same time with Backerberg (in 1955) Franz Buxbaum classification appeared. It was more natural and scientifically proved, as many scientists thought. Because of this it has become generally recognized among professional taxonomists of that time. Some time later (in 1967) David Hunt proposed his classification which included 84 stems and about 2000 species. Of course this classification was absolutely improper.
After Hunt some researchers inserted great changes into cactus systematization or even offered their own – Ritter, Benson and Rose, Bartlott. However new classification which could satisfy everyone did not appear.
If earlier cactus classifications were made by separate amateurs, now the situation has changed. Information capacity has grown and one person can not seize it all. If Backerberg system was based mainly on morphological characters, now you should consider seed structure, pollen structure, geographical interrelation, DNA structure etc. (That is why A. Doweld attempts to draw his own system based only on 1 character - seed cover structure – can not be taken seriously). In 1980s cactus section of the International Organization of Succulent Researching (ISO) made a special group "for searching the way of achieving the consensus in generic classification". Since that time many sessions were done by the group, now called "International group of Cactus systematization". Also some versions of classification were offered and even scientific works were done. Yet, in the head of the group such are "enlargers" as Hunt, Tailor and Anderson and in 1994, for example, only 104 stems were acknowledge by the group.
The last attempt to make the classification is the book "Cactus family" by A. Anderson, the member of the Group. The author does not pretend to make the new classification, he states the Group opinion, yet sometimes his own opinion does not go with the opinion of the Group. Anderson's classification has only 125 stems. Many botanists-taxonomists did not accept this classification. Russian amateurs also did not accept the classification and the absence of such stems as Notocactus, Sulcorebutia, Eriocactus, Neocholenia, Neoporteria, Gymnocactus etc. Of course, many innovations are quite acceptable as I think. I am used to integration of Ario- и Roseocactus, transfer Peleciphora valdesiana and Pelecyphora pseudopectinata to Turbinicarpus, including Mammollopsis, Solisia, Dolihothele and many other small monotypic stems into Mammillaria. I can even accept the integration of Gymnocactus and Turbinicarpus or Lobivia, Pseudolobivia и Echnopsis. However I can not admit the reducing of all "Chilean" into two stems – Copiapoa and Eriosice, or making two Rebutia and Parodia. Only by this especial personal point of view inscriptions on my pots can be descripted - Ariocarpus kotschoubeyanus, Turbinicarpus valdesianus, Mammillaria pectinifera, но Gymnocactus knuthianus, Lobivia cardenasiana, Neochilenia napina, Sulcorebutia erinacea etc.
On our cactus exhibitions in the plant list I sometimes write Backerberg's name of the stem in brackets: Mammillaria (Solisia) pectinata.
Appendix: Cactaceae taxonomy according A. Anderson
xHaageoespostoa (Haageocereus x Espostoa)
(Myrtillocactus x Bergerocactus)
(Pachycereus x Bergerocactus)