Key to the species of Agathotanais (females)

1. Antenna with two articles................................................... ............................................... A. manganicus Larsen, 1999

– Antenna with one article .................................................. 2

2. Uropod with one articulation between basal article and tip......................................................................................... 3

– Uropod without articulations between basal article and tip......................................................................................... 4

3. Length/width of pereonites 3 and 4 about 1.50; pleonites as wide as pereonite 6............................... A. ghilarovi

– Length/width of pereonites 3 and 4 almost 1.00; pleonites narrower than pereonite 6 ..... A. misakiensis sp. nov.

4. Fixed finger with two ventral simple setae; carpus of pereopods 1–3 lacking dorsodistal seta; pleonites narrower than pereonite 6 ............... A. ahyongi Larsen, 1999

– Fixed finger without ventral seta; carpus of pereopods 1 and 3 (no data for pereopod 2) with one dorsodistal seta; pleonites as wide as pereonite 6 ......... A. splendidus

– Fixed finger with one ventral simple seta; carpus of pereopods 1–3 with one dorsodistal seta; pleonites narrower than pereonite 6 ...................................................... 5

5. Dorsodistal simple seta on carpus of pereopod 2 long (longer than two-thirds of propodus length)................. 6

– Dorsodistal simple seta on carpus of pereopod 2 short (shorter than two-thirds of propodus length) ............... 8

6. Body stout (BL/CW 5.30); cephalothorax length equal to CW ...................... A. brevis Kudinova-Pasternak, 1990

– Body narrow (BL/CW more than 6.50); cephalothorax length longer than CW ..................................................... 7

7. Pereonite 3 shorter than wide, pereonite 4 longer than wide (length/width 0.90 and 1.10, respectively); dactylus of pereopods 1–3 naked................................. A. ingolfi

– Pereonites 3 and 4 longer than wide (length/width 1.15 and 1.30, respectively); dactylus of pereopods 1–3 with one simple seta ............................... A. hanseni Lang, 1971

8. Carpus and propodus of pereopods 4–6 with three and two distal spiniform setae, respectively ........... A. hadalis

– Carpus and propodus of pereopods 4–6 with one and three distal spiniform setae, respectively........................ 9

9. Pleonites narrow (pleonite width 0.75 times pereonite-6 width and 0.65 times CW); basis of pereopods 1–6 without dorsal small spines; carpus and propodus of pereopods 4–6 with ventral small spines ..................... ........................................................................... A. spinipoda

– Pleonites very narrow (pleonite width 0.65 times pereonite-6 width and 0.45 times CW); basis of pereopods 1–6 with dorsal small spines; carpus and propodus of pereopods 4–6 without ventral small spines.................... ........................................................... A. toyoshioae sp. nov.