So far it looks like a anisitsii/damsii. (I have never dug into the taxonomical differences between them, some authors/collectors treat them as separate species, while others place damsii as a subspecies under anitsii).

Pilosocereus pachycladus?

Coryphantha glandulifera KKR20 What is wrong with that? I guess glandulifera is a misspelling of glanduligera , which AFAIK is a valid name. Does it not fit the description of the species? Or do you want more data about where it was collected? (And, as I guess you know, KKR is Kracík, not Kníze)

Subverted wrote:8 ) Astrophytum...hybrid? Doesnt seem to fit with any pure species to me...

Why not? Looks like a young capricorne with spines that are not fully developed yet.

I have seen all of these "splotches" types before, but since they have seemed harmless I have never bothered to find out exactly what they are. The brown line on the Faucaria looks like a scar.

The bottom 2/3 of it are brown/white. I think it is corking, but it is very widespread. It's curved out to almost 90 degrees from where it goes into the ground. Will it be able to hold itself up? The base is super-thin and roots look like they're growing out at an angle to support it. I'm assuming ...

Epiphyllum oxypetalum is often called" night-blooming cereus".

The dark pollen makes me think anisitsii. A very sunburnt one .

Root mealies? They are very good at dehydrating cacti that require lots of water (like Pereskiopsis).
I doubt that the plant can be saved.

Butterfly wrote:How the sun burn could be all around the cactus body? Besides it never stands in a sunny place. It stands on the eastern window and receives some morning sun rays.

Then mites is a more likely cause, IMO. Can you see any mites close to the growing point? Or worse, on nearby plants?

Steve Johnson wrote: but the spent flower fell off when I brushed (and I mean brushed) against it. Is that normal, or could it be a sign that the plant was already starting to get sick?

Probably normal, Echinocereus flowers fall off very easily when they have dried up after flowering (unless they develop a fruit).

Aichybatoal wrote:Mystax is too squat. Mine is columnar and cylindrical.

You should not exclude mystax for that reason. When grown in less than ideal conditions cacti often stretch and become more cylindrical than they should.

or it could simply be developed by exposure to the suns rays. I don't grow Copiapoa, but I remembered something I read in Graham Charles's book Copiapoa that might be of interest: "In nature, some of these, like C. cinerea , develop a white waxy bloom on the stems [...]. Even in the best envir...

It might be rot, sometimes it starts from the top. I would cut again, about 3 cm from the top and using a sterilized knife.

martenfisher wrote:Pereskia grandiflora or also called grandifolia

P. grandifolia is the accepted name, grandiflora was listed as a synonym (used by gardeners) by Pfeiffer.