Caprella, Lamarck, 1801

Heo, Jun-Haeng, Shin, So-Yeon & Kim, Young-Hyo, 2024, A new species of the genus Caprella Lamarck, 1801 (Crustacea, Amphipoda, Caprellidae) from Korea, Zootaxa 5432 (3), pp. 436-444 : 442-443

Key to the Korean species of genus Caprella (modified from Lee & Hong, 2011)

1. Head smoothly rounded................................................................................ 2

Head rounded and with one to several upright projections..................................................... 3

Head angularly produced anteriorly and often with a frontal................................................... 4

2. Body completely smooth............................................................................... 5

Body with projections................................................................................. 6

3. Head with a small projection............................................................................ 7

Head with an acute long projection....................................................................... 8

Head with a pair of small projections............................................. C. acanthogaster Mayer, 1890

Head with small projections.................................................... C. polyacantha Utinomi, 1947

4. Head with a short dorsal projection or angular shape anteriorly................................................. 9

Head with an acute dorsal projection anteriorly............................................................ 10

5. Antenna 1 with longer than half of body.................................................................. 11

Antenna 1 with longer than half of body.................................................................. 12

6. Pereonites with dorsal projections but without lateral projections.............................................. 13

Pereonites without dorsal projections but with lateral projections........................... C. kroyeri De Haan, 1849

Pereonites with small tubercles............................................. C. multituberculum Lee & Lee, 1996

Pereonites with dorsal and lateral projections............................................ C. mutica Schurin, 1935

7. Pereonites with small tubercles.................................................. C. cristibrachium Mayer, 1903

Pereonites with 1–3 dorsal blunt projections............................................................... 14

8. Pereonite 2 without a projection ventrally................................................................. 15

Pereonite 2 with a projection ventrally............................................ C. californica Stimpson, 1856

9. Pereonite 2 without a projection ventrally................................................................. 16

Pereonite 2 with a projection ventrally................................................... C. equilibra Say, 1818

10. Pereopods 5–7, propodi with robust (grasping) setae........................................................ 17

Pereopods 5–7, propodi without robust (grasping) setae..................................................... 18

11. Pereopods 5–7, propodi with robust (grasping) setae proximally............................... C. mixta Mayer, 1903

Pereopods 5–7, propodi with robust (grasping) setae mesially................................ C. subtilis Mayer, 1903

12. Pereopods 5–7, propodi without robust (grasping) setae.................................. C. decipiens Mayer, 1890

Pereopods 5–7, propodi with robust (grasping) setae........................................................ 19

13. Pereonite 5 with a pair of projections dorsally............................................................. 20

Pereonite 5 with two pairs or more of projections dorsally.................................................... 21

14. Pereonite 5 with a projection dorsally................................................ C. arimotoi Takeuchi, 1993

Pereonite 5 with two or more projections dorsally....................................... C. verrucosa Boeck, 1871

15. Pereopods 5–7, propodi with robust (grasping) setae mesially................................................. 22

Pereopods 5–7, propodi with robust (grasping) setae proximally............................................... 23

16. Pereopod 7, propodus without robust (grasping) setae....................................................... 24

Pereopod 7, propodus with robust (grasping) setae.......................................................... 25

17. Pereopods 5–7, palmar margins of propodi concave....................................... C. penantis Leach, 1814

Pereopods 5–7, palmar margins of propodi convex....................................... C. andreae Mayer, 1890

18. Gills 3, 4 elongated............................................................. C. brevirostris Mayer, 1903

Gills 3, 4 rounded................................................................ C. megabranchia sp. nov.

19. Antenna 1 longer than half of body.................................................. C. gracillima Mayer, 1890

Antenna 1 shorter than half of body................................................ C. japonica (Schurin, 1935)

20. Pereopod 7, propodus without robust (grasping) setae...................................... C. simplex Mayer, 1890

Pereopod 7, propodus with robust (grasping) setae...................................... C. monoceros Mayer, 1890

21. Pereonites 1–4 with projection........................................................ C. eximia Mayer, 1890

Pereonites 1–4 without projection.................................................. C. linearis (Linnaeus, 1767)

22. Gnathopod 2, propodus elongated....................................................... C. simia Mayer, 1903

Gnathopod 2, propodus spoon-shaped.............................................. C. gigantochir Mayer, 1903

23. Pereonite 5 with two pairs of projection dorsally....................................... C. scaura Templeton, 1836

Pereonite 5 without projection...................................................... C. chelimana Mayer, 1903

24. Pereopods 5–7, propodi with robust (grasping) setae.................................. C. algaceus Vassilenko, 1967

Pereopods 5–7, propodi without robust (grasping) setae.............................. C. danilevskii Czerniavski, 1868

25. Gnathopod 2 on pereonite 2 is attached anteriorly................................. C. kominatoensis Takeuchi, 1986

Gnathopod 2 on pereonite 2 is attached mesially..................................... C. tsugarensis Utinomi, 1947

Gnathopod 2 on pereonite 2 is attached posteriorly..................................... C. subinermis Mayer, 1890