From the GameWatch interview:
編：　「シヴァ」や「ラムウ」はどうですか？
吉田氏：　あの2体も蛮神の予定です。特にエレメンタル四元素＋光闇あたりに関しては確定で蛮神かなと。
Ed.: What about "Ramuh" and "Shiva?"
Yoshida: Those two are also planned as primals. The four elements + light and dark, in particular, have been decided to be used as primals.
It will be Ramuh. Those of you who like the poor-man replacements can suck it.