Do you have any pictures or descriptions of the flowers? They are very important for identification. #1 should have large, yellow flowers if it is a longimamma or one of its close relatives. Bombycina seems right for #2. I don't think #3 is angelensis, it looks more like thornberi. Again, a picture of the flower would be useful.

Hi-de-ho, here to try some educating :) A species ought to be a taxonomically distinct grouping, having characteristics that identify all members as being the same species and different from other species. A species should mostly only reproduce with other members of the same species, although occsaional natural hybrids between species are found. A sub-species is a genetically distinct grouping within a species, but not sufficiently distinct to be treated as a separate species. Note that subspecies should be able to interbreed (if they can't they ought to be treated as a separate species) but do not actually do so in nature. This generally means that subspecies have different natural distributions. Note that separate areas of distribution for a species do not necessarily mean that there are separate subspecies. They may just be separate populations that are similar or identical, perhaps only falling into distinct ranges very recently, perhaps even since discovery. "v." or "var. is variety is an even lower level of taxonomic distinction below subspecies. You may occasionally also see the even lower level of "forma", but rarely in the cactus world. Each of these various names has strict taxonomic rules for how it should be published to be valid, and when it can be changed, etc. In common usage the rules are often ignored so that, for example, Echinocactus horizonthalonius ssp. horizonthalonius var. nicholii may just be referred to as Echinocactus nicholii. In this case, E. nicholii never existed as a species. Often the commonly used name was once a species name that is now considered to fall within a different species, so that the name is now either a subspecies or variety within that species. For example, the various Mammillaria decipiens names. Taxonomic names ought strictly to be placed in a different typeface to clearly delineate them in text. This is usually italics in normal text, but can be plain type within a paragraph of italic text or potentially anything else that makes the name more visible. If you've ever scanned a page of latin looking for the species name then you'll appreciate the use of italics! "cv." or cultivar is not a taxonomic term. Cultivars do not necessarily occur in nature, although a particular specimen from the wild may be selected and propagated as a cultivar. A cultivar could also be a hybrid within or between species, a vegetatively propagated mutant. Cultivar names should generally be placed inside parentheses and are not in a different typeface. Cultivar names should consist of the genus name and the cultivar name, the use of the original species or hybrid parent names are optional and purely informational. Cultivar names can be registered for certain plant breeders rights (different in different countries) but do not fall under other intellectual property rules. In fact a cultivar name cannot be registered as a trademark in the US and many other countries, and the plant patent application process is quite complex. Because of this, some plant breeders have taken to selling cultivars under a separate registered trademark name, a simple process that could in theory provide them exclusive use of the name through selling the name for royalties. In practice this has blown up in the faces of a few breeders because it is generally unenforceable.

To me A:Looks like- Old Lady cactus-mammillaria hahniana-white flowering cactus with reddish purple blossoms opening over silky haired body.B:Mammillaria polydera-an interesting cactus densly studded with knobby aeroles-C: could be Mammillaria erythrospermaD:Looks like a Chin Cactus --Found the information from a Cacti book I have I might be wrong though

Exciting as in actually grows, has cool flowers... just doesn't sit there and waits to die. Last one does look like Notocactus (or Parodia) buiningii, just the spines on mine are darker than pics I look up. The Parodia erubescens really does seem to match mine little red one a lot, there hasn't been any sign of a flower yet. I was way off guessing Mamm. The left one in the first pic... Mammillaria magnifica -? A clumper?