That's why I can't load my pictures here. If I could get them smaller in my phone...

Looks like Eriocactus warasii grown in deficience of sun. Check with looking glass it's base to exclude red mites, if no it will be corcking due to unsuitable conditions.

Thrips damage. Kill them twice.

My pleasure. It may be also it's v. albispinus.

Eriocactus leninghausii grown in deficience of sun.

Mammillaria magnifica grown in a deficience of sun. Have to be completely dry in winter.

Premature corking, probably due to small watering. Notocactus ottonis origined from southern Brazil, Uruguay and Paraguay in grasslands where year precipitation in high enough that's why in collections plant usually suffer from excessive dryness.

Aphids are easiest pests to eliminate, use any garden spray.

I don't tolerate pests on my plants.

Aphids IMHO

I'd try first fungicide spray then (better!) if no effect systemic fungicide. This fellow is bullet proof and cannot grow outdoors only in Finland.

Hello, i have the same question here, i've just bought an Echinopsis subdenudata, and im trying to figure out if by the current taxonomy it is Lobivia subdenudata or Lobivia ancistrophora?Because all of these two are recognized currently, and my question is what are the differences between these 2?...

F glaucescens,
Notocactus uebelmannianus

Karwinskiana has mostly white spines and white hairs in axils.

Mammillaria centricirrha (?)
M columbiana (?)
M discolor "Ginza Maru"