Challenge for Tephrocactus / Opuntia enthusiasts

[floring]

I have purchased this cactus on ebay last year where it was sold as Tephrocactus atroviridis. I only bought it based on it's compact appearance and then I decided to google it to learn more about it and surprise... the species may or may not be valid.

I say this because while I do see similar looking cacti labelled as Tephrocactus atroviridis, I also see identical cacti (to my eyes at least) labelled as Puna incahuasi / Cumulopuntia rossiana / Cumulopuntia pentlandii / Opuntia atroviridis.

Not all of the species above look the same, mind you. On some websites the species listed above look completely different. I tried liffle, for instance, and according to them atroviridis is a synonim of Austrocylindropuntia floccosa, which it most definitelly does not resemble one bit.

So.. which is it? Is this a defunct species, that got pulled into a different group? Are they all synonims? My hope is to find some definitive info to finally label this little guy.

[Lactus]

I think it looks like a young Tephrocactus atroviridis. It does look a lot like Puna incahuasi and they could be the same plant... It might be interchangable..

[Aiko]

It does look a lot like Puna incahuasi and they could be the same plant... It might be interchangable..

I think Puna subterranea f. incahuasi is a totally different plant. It has soft spines. This is probably not the same for this Tephrocactus.

[Lactus]

It does look a lot like Puna incahuasi and they could be the same plant... It might be interchangable..

I think Puna subterranea f. incahuasi is a totally different plant. It has soft spines. This is probably not the same for this Tephrocactus.

You're probably right. When I Google Puna subterranea f. incahuasi, I see both soft and harder spines. Maybe there is some mislabelling going around. I'm seeing a lot of sellers selling Puna subterranea f. incahuasi with the harder spines like the one pictured.

[phil_SK]

I've bought this plant (here in the UK) labelled Tephrocactus atroglobosus. It's neither atroviridis (a synonym of Austrocylindropuntia floccosus) nor atroglobosus (a synonym of T. nigrispinus). After years of wondering how this misidentification came about, my best guess is that someone had a go at identifying their plant using a photo in Backeberg's Cactus Lexicon, the main authorative guide for 20 years after it's publication in English in 1977 - see https://www.cactuspro.com/lecture/Backe ... 76.en.html Perhaps atroglobosus --> atroviridis is a further mutation in label writing. Your plant is Cumulopuntia rossiana.
Puna incahuasi and Puna subterranea f. incahuasi are unpublished names (Puna really should be abandoned) for a plant that is best treated as Cumulopuntia subterranea subsp. pulcherrima. I think it bears as much a resemblance to rossiana as to subterranea personally.

[floring]

I managed to find a copy of Michael Kiessling's 'Tephrocactus and other pricky pears' which was referenced in other conversations and funny enough he actually has a plant called Austrocylindropuntia atroviridis listed there, which I didn't expect. He also has Cumulopuntia rossiana and subterranea in his list, and indeed, rossiana seems to be a better match for my plant, main difference seems to be the glochids, which are missing in my case.

I added them below, for reference only. Please delete if posting them here breaks any rules.

[DaveW]

Agreed. Looks like what I obtained at the Tephrocactus Study Group last AGM in UK as rossianus.

[floring]

Ok... I'm ready to accept it's a C. rossiana. Thank you all for your input and if new opinions should arise, don't be shy!