What is a Hungarian Horntail?

Newt Scamander's description of a Hungarian Horntail from the Fantastic Beasts book

Supposedly the most dangerous of all dragon breeds, the Hungarian Horntail has black scales and is lizard-like in appearance. It has yellow eyes, bronze horns and similarly coloured spikes that protrude from its long tail. The Horntail has one of the longest fire-breathing ranges (up to fifty feet). Its eggs are cement-coloured and particularly hard-shelled; the young club their way out using their tails, whose spikes are well developed at birth. The Hungarian Horntail feeds on goats, sheep and, whenever possible, humans.

Fantastic Beasts and Where to Find Them

By J.K. Rowling