For the Apex, a Theremin! Seriously one of the most classic sci-fi instruments ever - you play it without ever touching it. For the Glitch, a Lyre! Strange but lovely instrument, it occupies the midground between the harp and precursors to the modern guitar, like the lute. The Hylotl could use a Shakuhachi, a bamboo flute that's been long associated with classic Japanese music. The Avians... how about a traditional Mayan Clay Flute? For the Florans, an African Drum kit consisting of, at a minimum, a Djembe (Goblet drum), Dunun (Barrel drum) and Shekere (Gourd & Bead rattle) would be nice.
we do have the drum, floara has them, and also metal drums, harp does cover it, we have few flute which I guess we do need few them more...