Dragonewts are B rank demons. Dragonewts are far descendants of dragons.
The appearance of dragonewts varies by gender.
Some Dragonewt don't look much different than lizardmen. Their dark-green color changes to dark-purple. They sprout dragon wings and horns and are covered by dense scales which act as a multi-layer barrier.
Other Dragonewt have a rather beautiful human appearance. Furthermore, they can also cover themselves with dragon scales, sprout wings and horns at will.
Gabil's squad of 100 developed the ability to transform into dragons for a limited time. The power of this form is notable as Gabil was confident that each one could fell an imperial airship, Rimuru himself considers the Tempest's strongest force. However, the drawbacks hit hard and if they don't go berserk they'll still become incapacitated for two days following the use of this form.
They gained this skill from Demon Lord Rimuru's Harvest Festival, allowing them to get closer to their draconic roots.