Diacyclops, Kiefer, 1927

Karanovic, Tomislav, 2024, Six new species of Diacyclops (Copepoda: Cyclopoida) from Australia, Zootaxa 5541 (2), pp. 101-143 : 139-140

Key to Australian species of Diacyclops :

1. Female antennula of less than 17 segments................................................................. 4

- Female antennula 17-segmented......................................................................... 2

2. Third endopodal segment of fourth leg with inner spine longer than outer spine.............. D. bisetosus (Rehberg, 1880)

- This segment with inner spine shorter than outer spine........................................................ 3

3. Principal caudal setae with breaking planes; dorsal caudal seta shorter than innermost caudal seta................................................................................................... D. bicuspidatus (Claus, 1857)

- Principal caudal setae without breaking planes; dorsal caudal seta longer than innermost caudal seta....... D. leijsi sp. nov. 4. Female antennula 10-segmented................................................... D. huntervalleyensis sp. nov.

- Female antennula of more than 10 segments................................................................ 5

5. Female antennula 11-segmented......................................................................... 6

- Female antennula 12-segmented......................................................................... 8

6. Exopod of first leg 2-segmented........................................................ D. tomlinsonae sp. nov.

- Exopod of first leg 3-segmented.......................................................................... 7

7. Third exopodal segment of first to fourth leg spine formula 2.3.3.3......................... D. cryonastes Morton, 1985

- This segment spine formula 3.4.4.3........................................................ D. hancocki sp. nov.

8. Outer principal caudal seta strongly reduced............................................ D. ballaballaensis sp. nov.

- Outer principal caudal seta well-developed................................................................. 9

9. First exopodal segment of first to fourth legs without inner seta................................................ 12

- This segment with with inner seta....................................................................... 10

10. Dorsal caudal seta as long as outer principal caudal seta................................. D. scanloni Karanovic, 2006

- Dorsal caudal seta shorter than outer principal caudal seta.................................................... 11

11. Labrum with very convex cutting edge............................ D. reidae De Laurentiis, Pesce & Humphreys, 1999

- Labrum with slightly convex cutting edge.......................... D. einslei De Laurentiis, Pesce & Humphreys, 1999

12. Dorsal caudal seta as long as outer principal caudal seta.............................. D. sobeprolatus Karanovic, 2006

- Dorsal caudal seta shorter than outer principal caudal seta.................................................... 13

13. Dorsal caudal seta about as long as innermost caudal seta............................... D. cockingi Karanovic, 2006

- Dorsal caudal seta much longer than innermost caudal seta................................................... 14

14. Seminal receptacle large and mushroom-like................................................ D. eberhardi sp. nov.

- Seminal receptacle small and ovoid...................................................................... 15

15. Third endopodal segment of fourth leg with two apical spines...... D. humphreysi humphreysi Pesce & De Laurentiis, 1996

- This segment with 1 apical spine....................................... D. humphreysi unispinosus Karanovic, 2006