Antarcturidae Poore, 2001

Poore, Gary C. B., 2015, Halearcturus, a new genus of Antarcturidae Poore, 2001 (Crustacea: Isopoda: Valvifera) with a key to genera of the family, Memoirs of Museum Victoria 73, pp. 13-18 : 13-14

Key to genera of Antarcturidae Poore, 2001

1. Pereopods 2–4 bearing few well spaced straight stiff setae along flexor margins of carpus to propodus; body and limbs covered with fine short setae 2

– Pereopods 2–4 bearing numerous closely and regularly spaced fine ‘filter setae’ along flexor margins of at least merus to propodus; body and limbs smooth 3

2. Pereonal and pleonal segments each with pair of dorsolateral spines of similar lengths; eyes unpigmented Thermoarcturus Paul & Menzies, 1971

– Pleotelson with 1 pair of dorsolateral spines much longer than others; eyes pigmented Spinarcturus Kensley, 1978

3. Antenna flagellum of 9 or more short articles 4

– Antenna flagellum of 4 or fewer short articles 9

4. Pleonite 1 free from remaining segments of pleotelson 5

– Pleonite 1 fused to remaining segments of pleotelson 7 5. Pleonites 5 and 6 with middorsal spines Marmachius Poore, 2012

– Pleonites without middorsal spines 6

6. Head without pair of spines between eyes, pereon and pleon without submedian, sublateral and supracoxal spines; pleotelson without prominent medial posterior spine dorsal to margin Furcarcturus Baltzer, Held and Wägele, 2000

– Head with pair of spines between eyes, pereon and pleon with pairs of submedian, sublateral and supracoxal spines; pleotelson with prominent medial posterior spine dorsal to margin Oxyarcturus Brandt, 1990

7. Pleotelson with paired submedian spines or tubercles, with marginal lateral spines Antarcturus zur Strassen, 1902

– Pleotelson without paired submedian spines or tubercles, without marginal lateral spines 8

8. Head without pair of submedian spines between eyes; pereonites without middorsal, sublateral or supracoxal spines (tubercles at most) Litarcturus Brandt, 1990

– Head with pair of submedian spines between eyes; pereonites with sublateral and supracoxal mushroom-like tubercles; pereonites 1–4 with middorsal tubercles on posterior margins Tuberarcturus Brandt, 1990

9. Pleonites without middorsal spines 10

– One or more pleonites with middorsal spines or tubercles 17

10. Head with pair of submedian spines 11

– Head without pair of submedian spines 15

11. Eyes absent 12

– Eyes present, pigmented 13

12. Pereonites with paired submedian and sublateral tubercles; pereopods 2–4 with regular rows of long setae along flexor margins of merus–propodus, unguis setiform Abyssarcturus Kussakin and Vasina, 1995

– Pereonites without paired submedian and sublateral spines; pereopods 2–4 with regular rows of long setae along flexor margins of merus–dactylus, unguis short, curved Glaberarcturus Kussakin and Vasina 1998

13. Pleotelson with paired submedian and lateral spines, with prominent paired posterior sublateral spines Fissarcturus Brandt, 1990

– Pleotelson with prominent medial posterior spine dorsal to margin or apex prominently produced 14

14. Pereopods 2–4 with regular rows of long setae along flexor margins of merus–propodus Acantharcturus Schultz, 1981 – Pereopods 2–4 with regular rows of long setae along flexor margins of merus–dactylus Chaetarcturus Brandt, 1990

15. Pleotelson without pairs of sublateral spines 16

– Pleotelson with prominent pair of sublateral spines near midpoint Caecarcturus Schultz, 1981

16. Eyes pigmented; pleotelson dorsal surface convex, not differentiated from lateral margin, with medial spine prominently posteriorly produced Cylindarcturus Schultz, 1981

– Eyes absent; pleotelson dorsal surface bulbous, differentiated from lateral margin by longitudinal groove, without prominent medial posterior spine Globarcturus Kussakin and Vasina, 1994

17. Pleotelson with 2 middorsal tubercles near apex, with paired submedian and sublateral spines Halearcturus gen. nov.

– Pleonites 2 and 3 with middorsal spine; pleotelson without pairs of submedian and sublateral spines 18

18. All pereonites with paired sublateral tubercles and supracoxal spines; pleotelson with prominent paired posterior sublateral spines; pereopods 2–4 with unguis short, curved Mixarcturus Brandt, 1990

– Pereonites without paired sublateral spines or supracoxal spines; pleotelson without prominent paired posterior sublateral spines more dominant than other spines; pereopods 2–4 unguis setiform Pleuroprion zur Strassen, 1903