|“||Speedifist's Riding-Dragon is a Swiftglider, as fast and as quick as its rider.||”|
|— Official Book series Website|
The Swiftglider is a dragon mentioned on the Official How to Train Your Dragon Books Website.
There is not much information for the Swiftglider, beyond that it is a Riding Dragon, and that it is very fast. Most likely this dragon is designed for speed, and also gliding, due to its name.