Key to species of Amathillina

1. Body keel starts from the first to third pereonite ...... 2

- Body keel starts from the sixth pereonite or later ...... 3

2. Pereonites 1–2 with well-developed dorsal spines, urosomite 1 humped ................................................ A. spinosa

- Pereonites 1–2 with barely visible crest, urosomite 1 not humped ........................................................ A. cristata

3. Body keel present only on pleosome ... A. maximowiczi

- Body keel present on pereonites 6–7 and pleosome ... 4

4. Antenna 1 accessory flagellum bi-articulated, last pleonal projection rounded ...................................... A. pussila

- Antenna 1 accessory flagellum tri-articulated, last pleonal projection triangular ..................................... A. affinis