Okay, let's try this one:
- Vervet monkey
- Rhesus macaque
- Mantled guereza
- Pygmy marmoset
- Emperor tamarin
- Black howler monkey
- Geoffroy's spider monkey
- Philippine flying lemur
- Indian giant squirrel
- Northamerican porcupine
- Common genet
- Coati (any)
- Marten (any)
- Long-tailed pangolin
- Tamandua (any)
- Goodfellow's tree-kangaroo
- Jackson's chameleon
- Sulawesi lined gliding lizard
- Blue poison dart frog
- Coconut crab
Gosh, 20 really doesn't feel like enough, I had a lot of candidates that got the axe xD
By the way, you've forgotten to remove the lion-tailed macaque from the table after moving the other macaques down.