Pleusymtinae Bousfield & Hendrycks 1994

Key to genera of Pleusymtinae based on the key of Hendrycks & Bousfield (2004)

1. Coxa 1 anterodistally bent forwards; coxae 1–3, posterodistal cusps often singly large, or medium and multiple (2–5 in number)................................................................................................ 2

- Coxa 1 normal, direct ventrally; coxae 1–3, posterodistal cusps usually single, medium to small in size.................. 8

2. Posterior pereon and pleon strongly mid-dorsally carinated..................................................... 3

- Body segments dorsally smooth or nearly so................................................................ 5

3. Antenna 1, peduncular segment 1 with strong anterodistal process; urosome segment 2 occluded dorsally by segments 1 & 3..................................................................................................... 4

- Antenna 1, peduncular segment 1 lacking anterodistal process; urosome 2 not occluded dorsally....................................................................................... Budnikopleustes Hendrycks & Bousfield, 2004

4. Rostrum very strong, exceeding segment 1 of antenna 1; basis of pereopod 5 is linear.......... Vinogradovopleustes n. gen.

- Rostrum medium length, not exceeding segment 1 of antenna 1; basis of pereopod 5 broadened, with distinct posterior lobe................................................................... Rhinopleustes Hendrycks & Bousfield, 2004

5. Antenna 1, peduncular segment 1 with strong anterodistal process; coxae 2–4 narrow, deep; urosome 2 not occluded dorsally................................................................. Anomalosymtes Hendrycks & Bousfield, 2004

- Antenna 1, peduncular segment 1 lacking anterodistal process (may have posterodistal tooth); coxae 2–4 normal, depth <twice; urosome 2 partly to fully occluded dorsally............................................................ 6

6. Rostrum weak, not exceeding anterior head lobe; lower lip, outer lobes widely separated, inner lobe shallow, flat; mandibular left lacinia 8–9 dentate; urosome 2 not occluded dorsally.................. Kamptopleustes Hendrycks & Bousfield, 2004

- Rostrum moderate to very strong, exceeding anterodistal head lobe; lower lip, outer lobes not widely separate, inner lobes sloped; left lacinia 6–7 dentate; urosome 2 nearly or completely occluded dorsally.................................. 7

7. Rostrum medium; antennal peduncular segment 1, process strong; pereopods 5–7, posterior margin of basis angular; uropod 2, outer ramus much shorter than inner ramus (<2/3)..... Pleusymtes pribilofensis subgroup (by Hendrycks & Bousfield 2004)

- Rostrum often strong; antennal peduncular segment 1, process weak; pereopods 5–7, posterior margin of basis rounded; uropod 2, outer ramus 80% of inner.................................................. Pleustomesus Gurjanova, 1972

8. Antenna 1, peduncular segments 2 & 3 very short, <½ of segment 1; pereopods 5–7 closely subequal in shape and size; mandibular left lacinia 11-dentate.......................................... Holopleustes Hendrycks & Bousfield, 2004

- Antenna 1, peduncular segments regular, combined length> ½ of segment 1; pereopods 5–7 usually slightly differing in size and shape; mandibular left lacinia 6–7 dentate............................................................... 9

9. Antenna 1 & 2, peduncular segments richly setose posteriorly; pereopods 1 & 2 (gnathopods 1 & 2) very weak, subequal, carpus longer than propodus; coxae 1–3, posterodistal cusps very small......... Heteropleustes Hendrycks & Bousfield, 2004

- Antenna 1 & 2, peduncular segments devoid of setae; pereopods 1 & 2 (gnathopods 1 & 2) regular; coxae 1–3, posterodistal cusps short to medium................................................................................. 10

10. Antenna 1, peduncular segment 1 with posterodistal tooth; epimeral plate 3, hind corner with posterodistal “hook”..................................................................................... Pleusymtes J.L. Barnard, 1969

- Antenna 1, peduncular segment 1 lacking posterodistal process; epimeral plate 3, hind corner squared, regularly acuminate or produced.......................................... Pleusymtes mucida subgroup (by Hendrycks & Bousfield 2004)