Confidence: I'm as sure as I can be.
Notes: I am being picky here. There are several named varieties of Puccinia urticata, each variety with one or very few specific sedge species as alternate hosts. When on these hosts they differ in spore size, etc. and can be demonstrated as separate entities. When on nettle, as far as I know, these varieties are indistinguishable without host infection or DNA studies. So a rust on nettle CANNOT BE NAMED TO VARIETY. Furthermore, when Puccinia urticata was first recognised as a separate species, back in 1917, I don't believe that the alternate host of the original specimen on which the name was based was known, and "var. urticata" can only be defined by the original "type" specimen. It must follow that actually nobody knows what "var. urticata" is! It is wrong to use "Puccinia urticata var. urticata" as a general name for a rust on nettle. [Mushroom Lady is in good company though - someone who doesn't understand the rules of nomenclature has gone through the BMS database and re-labelled all the records of P. urticata on nettles as "Puccinia urticata var. urticata" - a bad mistake in a professional database. I shall have words ...] Alan