Anandakanda 1.21.43

1.21.43

aṣṭacchadeṣv aṣṭavargāny aśahādyaiḥ paraistribhiḥ /
kādyaiśca pañcabhirvarṇairaṣṭavargāḥ samīritāḥ //

On the eight petals, the eight groups [of consonants] beginning with a, śa, ha, and the next three [groups] / along with the five letters beginning with ka—these are declared as the eight groups.