I saw this Schefflera last year at the Los Banos Garden show. It looks similar to what was identified in Madulid's book as Cephaloschefflera blancoi. It has graceful leaf grwoth and fine flower sprays.
I thought this was the smallest Philippine species as it was named as Schefflera microphylla or small-leafed Schefflera. It grows in the rocky mountains of Zambales at high humidity areas.
The smallest species I have seen so far is this one, sold by a stall in Centris a few years back. A plant expert said it grows in high elevation and humidity in the mountains of Northern Luzon. Not sure if it can thrive in hot and dry Manila.