Lobivia subdenudata continues to be a popular choice of garden centres and DIY chains, especially the form with abundant fluff in the areoles, sometimes seen treated as 'fuzzy navel'. Mine came from a garden centre some years ago but didn't do very well for a long time. It is starting to look more healthy and has reached flowering size.
I have a couple of other plants that are not quite so fluffy. This first one originally came from Ron Wood's Cruck Cottage Cacti in Pickering.
And another, similar plant, from Harry Middleditch.
Subdenudata was described for plants found near Entre Ríos in Tarija, Bolivia. There are a few other plants that are quite widespread in cultivation that were found in that area but have spines.
Lau 941 is from Villamontes, around 50 miles east:
Lau 400, from Entre Ríos, variously seen as "sp. nova" (despite being collected in 1970), E. tapecuana, or the n.n.s E. tapecuana v. tropica or E. tortispina.
And here's yet another form, claiming to be from Entre Ríos but s.n. It has smaller bodies and slightly longer spines.
The New Cactus Lexicon treated subdenudata as a form of E. ancistrophora but tapecuana (published 1965) as a form of E. pamparuizii (published 1970). I'm inclined to believe that all of these I've shown from Bolivia are the same but subdenudata might be the oldest name.