I have doubts regarding Akura Jebia, Doragyurosu and Giaorugu. They don't follow the naming convention of the Subspecies in Japanese.
Were they actually confirmed to belong in this group despite that?
I'm not completely sure about it, i guess they are Subspecies lore-wise but considered separate monster Gameplay-wise. Same goes for Midogaron or Rebidiora. As you can see, Dora, Giao, Mido and Rebi are the only "Subspecies" who got a Zenith Species.
Obviously i would wait for a more accurate answer than mine.
https://www.famitsu.com/pcent/news/1218690_1341.html - ”アクラ･ヴァシム”の亜種
Apparently the first link doesn't work however i do see a "亜種" and that's the important part.
Kudos to Banned