Diacyclops Kiefer 1927

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