Hebefustis

Kaiser, Stefanie, 2008, First record and new species of the genus Hebefustis Siebenaller & Hessler, 1977 (Isopoda: Asellota: Nannoniscidae) from the deep Weddell Sea Basin *, Zootaxa 1866, pp. 467-481 : 481

Key to the species of Hebefustis

1. Pereonite 6 and 7 with acute, distally directed posterolateral margins.........................................................2

- Pereonite 6 and 7 with rounded posterolateral margins................................................................................7

2. Pereonite 2 in female and/or male with a robust seta or spine on the anterolateral corner..........................3

- Pereonite 2 without a seta or spine .......................................................................... Hebefustis hexadentium

3. Second article of antennula with 4 broom setae, pereonite 2 in female and male with a robust spine on the anterolateral corner, female antenna with 12 flagellar articles, male pleopod 1 widest distally .................... ................................................................................................................................... H. clareolithis sp. nov.

- Second article of antennula with <4 broom seta..........................................................................................4

4. Male pleotelson with double angles ............................................................................................ H. cornutus

- Male pleotelson with rounded posterior margin...........................................................................................5

5. Operculum length 0.9 times pleotelson length, posterolateral spines about 0.9 from anterior margin, article 5 of antennula length 4.8 times width, sympod of male pleopod 1 with numerous setae (>15) ..... H. vitjazi

- Operculum length <0.9 times pleotelson length, posterolateral spines less than 0.9 from anterolateral mar- gin................................................................................................................................................................6

6. Article 5 of antennula increasing in width distally, male pleopod 1 with distinctive ridges on ventral sur- face .................................................................................................................................................. H. dispar

- Maxilliped with 2 coupling hooks, pereonite 2 just with robust seta in male .............................. H. hirsutus

7. Posterolateral spines of pleotelson strongly pronounced in female, article 5 of antennula <2.4 times longer than wide ............................................................................................................................... H. alleni

- Posterolateral spines only slightly pronounced in female, terminal article of antennula length> 2.4 times width.............................................................................................................................................................8

8. Posterolateral spines <0.3 from anterior margin, male pleotelson with strongly produced double angles (different to H. cornutus ), pereonites 1–4 with strongly produced anterolateral margins ........ H. primitivus

- Posterolateral spines>0.3 from anterior margin, male pleotelson with rounded posterior margin..............9

9. Pleotelson with a distinctive, strongly rounded posterior margin, operculum with a straight distal margin.. ..................................................................................................................................................... H. robustus

- Pleotelson posterior margin just slightly curved, with a softly rounded distal margin...............................10

10. Body length <3.8 times width, posterolateral spines 0.8 from anterior margin ................................. H. par

- Body length> 4.3 times width, posterolateral spines <0.8 times from anterior margin............................11

11. Article 5 of antennula length 4.5 times width, posterior margin of pleotelson rounded .................. H. vafer

- Article 5 of antennula length 3.8 times width, posterior margin sharply tapering distally ..... H. mollicellus