That was an interesting illustration you linked us to,
Ivriniel.

My question is this: Is he a solo singer or someone in a particular group or band?

It makes sense that the Fellowship didn't see (or make note of seeing) such things, they worrying about fighting to survive.
I thought about Bilbo fighting the giant spiders in
The Hobbit. They aren't referred to by gender at all, which makes sense; because Bilbo was trying to fight to survive and rescue his friends, not having the time to spare to wonder if they were boy or girl spiders.