Lavasioth

From Monster Hunter - Wiki on Neoseeker

The volcanic Piscine

Lavasioth (Japanese name: Volganos) is a new addition to Monster Hunter Frontier, Monster Hunter Portable 2nd G and Monster Hunter Freedom Unite. This creature swims in lava and is able to splash large amounts of magma at the surface as well as spit it out of its mouth. Once on land the Wyvern attacks those close to it by leaping high into the air, slamming down on those under it. It also flops onto stomach, sliding and squirming around, severely damaging whomever it hits.

This beast is a very tough kill, hiding in the lava and shooting giant balls of magma at you makes him annoying... Shock traps only work on him, pitfalls don't. It is speculated that this is the lava sub-species of Plesioth.