For me both middle layers Look like ayous, though donic states limba for one.
You can see it by looking at the 45° diagonal pattern.
No need to inspect it by eye. Composition is on donic website. Its probably the only manufacturer that actually specifies which materials they've used. Which is great and we all should be supportive of that. Props to DONIC.
DTCI: 7 plies of Kiri (inner), Hybrid Aramid Carbon (3+5), Ayous (2&6), Koto (1&7, outer)
DLHXC: 7 layers of Kiri (inner), Hexamid Carbon (3+5), Limba (2+6), Koto (1+7 outer)
EDIT1: Yeah Limba looks close to ayous, but is a little darker and gets darker with use. They can look very close to each other though and are not far off in the terms of properties:
-LIMBA
Janka Hardness: 670 lbf (2,990 N)
Elastic Modulus: 1,520,000 lbf/in2 (10.49 GPa)
-AYOUS
Janka Hardness: 440 lbf (1,960 N)
Elastic Modulus: 934,000 lbf/in2 (6.44 GPa)