From ErfWiki

Speculation

A non-humanoid mount unit in the shape of a large lizard with a puckered mouth - a sour faced salamander perhaps. Seems to be able to spit what is presumably some corrosive or poisonous substance at enemy units.^Erf-b1-p025

Used as a mount by Jetstone.^{Erf-b1-p010Erf-b1-p097Erf-b1-p109}

Can enter tunnels, despite being a heavy unit.

Mey be related in some fashion to Dwagons (similar appearance, posession of a breath attack).