User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-6974847-20130729183655/@comment-4009941-20130729193841

Answered this before. Lord Loss please update that stuff at the top of the page......

Its real name is "Unknown" Its just another specis of Rath not even a subspecies that is very rare and possibly older than the current common ones we know today.

Capcom has said its not exactly a "Rathian" just a relative so some of them can even be male. Goa appears to live on another continent so far and these "Unknown" gather rarely in the Swamp, Desert and most powerful(Maybe elder) ones live outside the Tower.

It is only NICKNAMED "Black Rathian" as a fan name.

Unlike "Rathians", "Unknown" has Pores on its underside that release some gas(Maybe acidic), A thicker unlike Rathalos or Rathian tail, Large ejectable wing claws filled with the same substance in the gas(Weakens defence) that  leaks out still even after it hit the ground, Is able to fly at extreme speeds, Has Venom(poison) in its claws like a Rathalos would, can leave behind blue sparks in the air kinda like Teo when making explosions with powder after making a huge explosion and can produce a beam like a Gravios.

My theory would be a guess that it would be a early relative of the raths that started somewhere close to when Armor Shell Wyverns(Leads to Rathalos) and Heavy Shell Wyverns(Leads to Diablos and Gravios) split from Tigrex.