Help with four cacti

[tacrolimus]

Hello all.
These are some of my recent acquisitions.
They are four small cacti which I cannot classify.
I would really appreciate if someone could tell me their correct name or even just their genus.

Thanks
Luigi

[vlani]

An interesting bunch
1- Ancistrocactus uncinatus, probablu brevihamatus
2- The common Mamm.elongata I think.
3 - looks like Pyrrhocactus strausianus = Eriosyce strausiana
4 - another Eriosyce, a bit hard for me to tell which one

[tacrolimus]

Thank you for your help.
Your answer confirms what i've been told on another forum regarding the first one, namely a Glandulicactus uncinatus (a synonymous of Ancistrocactus uncinatus if i'm not mistaken).
As for the second picture, i ventured a M. microhelia, but you are far more expert than me, so i'm going to take in great care your classification.
Of course thanks alot for the two further classifications as well.

Thanks again.
Best regards
Luigi

[vlani]

Micrihelia is a very good possibility. It is closely related to elongata, and this is a seedling - they may look very similar.They even make hybrids with each other. They should probably belong to the same species.
It needs to grow a bit and get more sun, then you will easily see which one is that.