Hellsteethers are a presumed group of closely related dragons, perhaps a Genus. The only known specific type or species of Hellsteether is the Snub-Nosed Hellsteether. This would be similar to the fact that there are a group of different types of Squirrelserpent dragons, of which two types we know about are the Lesser-Spotted Squirrelserpent and the Shortwing Squirrelserpent.
The Snub-Nosed Hellsteether is so called because of its shortened, or "snubbed", muzzle. In The Incomplete Book of Dragons, there is a picture of an unknown Hellsteether. It has the characteristic double set of jaws, but clearly not a snub-nose. Therefore it is not a Snub-Nosed Hellsteether, but some other un-named species.
Hellsteethers are shown to give a warning sound when hunting prey:
|“||The Hellsteethers softly rattled their teeth, with that dreadful warning rattle that turned Vikings' hearts to ice when they heard it surrounding their ships in the dead of night.||”|
|— How to Fight a Dragon's Fury|
A Hellsteether appears on the inside front cover of this book, but is not described further.