Chris,
Even though North Hills lists this on their web site, I think it likely that this was a misspelling of "ciliosum" or "cilliosum". Formal names of plants appearing in print is "magically significant" to professionals working in the field of biology. It's serious business who gets to name what plant and what constitutes a new plant that is "name-able", especially concerning species names. Careers can depend on it.
As hobbyists, we have a responsibility to try to maintain correct names on what we grow, if we share with others. Thus, if NH called your plant "Citiosum", then you should use that name, unless an "authority" or NH tells you otherwise. However, it is important for them to let you know if their source used the capitalized or lower case form of the name. Why is this? Well by convention, species names are lower cased, and hybrid varieties (or ones named by non-professionals), called varietal names, appear in caps in quotes.
"Ciliosum" is a species name for a species of Sempervivum (capitalized here because it is at the beginning of the sentence), so its formal plant name would be "Sempervivum ciliosum". Within the species "Sempervivum ciliosum", you can have multiple subspecies such as Sempervium ciliosum ssp borissi or potentially varietal named cultivars such as Sempervivium ciliosum 'Twit' (I just made that name up, it is not a real variety).
So since the original name was capitalized Sempervivum 'Citiosum' this should be treated as a varietal name until we can learn otherwise.
To add to the confusion on this case, the NH picture of S. 'Citiosum' looks a lot like S. ciliosum!
And, they (NH) have plants named "cilliosum" used as a species name. Perhaps NH misspelled the name on their web site or alternatively they are using the name given to them.
This name confusion is actually more common then you may suppose. As people try to keep track of names and tag their plants, its inevitable that mistakes will happen. When the mistake gets passed on to others, uncertainty regarding the original name occurs. And there are always those that just don't care about the real names of their plants, as astounding as that appears to be!
