This was first hinted at during the end of the Monster Hunter World: Iceborne presentation of Acidic Glavenus at San Diego Comic-Con 2019.
The three new subspecies have finally been revealed and they are;
Viper Tobi-Kadachi is imbued with a poison attack
Nightshade Paolumu releases sleep breath upon hunters
Coral Pukei-Pukei attacks with a water barrage instead of poison.
Below are three subspecies gameplay. (video source Arekkz Gaming)
Viper Tobi-Kadachi
[embedyt] https://www.youtube.com/watch?v=liWJRJCkuOg&width=720&height=405[/embedyt]
Coral Pukei-Pukei
[embedyt] https://www.youtube.com/watch?v=TDcU9lKo3nA&width=720&height=405[/embedyt]
Nightshade Paolumu
[embedyt] https://www.youtube.com/watch?v=FQkHHpF4Zvw&width=720&height=405[/embedyt]