Paraonidae, , Strelzov, 1973

Sikorski, Andrey, 2017, The Paraonidae (Annelida: Sedentaria) from Norway and adjacent seas, with two new species, four new records, and a redescription of Paraonides nordica Strelzov, 1968 based on type material, Zootaxa 4320 (1), pp. 41-67 : 62-63

Key to species of Paraonidae reported from Norwegian and adjacent waters

1. Some notochaetae as modified (acicular, forked) chaetae......................................................2

- All notochaetae as capillary ones.........................................................................9

2. Modified notochaetae of anterior chaetigers forked, those of median and posterior ones acicular with subterminal spine.....3

- All modified notochaetae forked......................................................................... 4

3. Subterminal spine attached directly to stem, antenna minute and papilliform or absent in younger specimens (see remarks for the species)....................................................................... Cirrophorus branchiatus

- Subterminal spine attached to a subdistal knob of the stem, antenna always absent................... Paradoneis armata

4. All neurochaetae of posterior chaetigers capillary ones....................................................... 5

- Neuropodia of posterior chaetigers bearing an enlarged spine-like ventral chaeta....................................8

5. All dorsal podial lobes of prebranchial and branchial region short and tuberculate; branchiae numbering up to 15 pairs, stout and short (up to four times as long as wide); antenna not observed........................... Cirrophorus brevicirratus .

- Dorsal podial lobes of chaetiger 1 tuberculate, then increasingly longer becoming digitiform on central branchial region; lobes shorter in postbranchial region........................................................................... 6

6. Antenna short and lanceolate; branchiae numbering up to 33 pairs, thin and long (up to six times as long as wide)............................................................................................. Cirrophorus furcatus .

- Antenna absent; branchiae numbering 15 or less pairs......................................................... 7

7. Four prebranchial chaetigers; branchiae numbering up to 15 pairs; about four times as long as wide, shorter than body width....................................................................................... Paradoneis mikeli

- Three prebranchial chaetigers; branchiae numbering up to 12 pairs; about six times as long as wide, longer than body width.......................................................................................... Paradoneis lyra

8. Branchiae arranged in 6–12 pairs, bearing cilia on outer and inner margins......................... Paradoneis eliasoni

- Branchiae arranged in 14–19 pairs, bearing cilia only on outer margin........................ Paradoneis andreae n. sp.

9. Postbranchial neuropodia without modified capillaries...................................................... 10

- Postbranchial neuropodia bearing some sort of modified chaetae (acicular or hooked chaetae, enlarged capillaries)....... 1 1

10. Branchiae present, numbering four to six pairs................................................ Paraonides nordica

- Branchiae absent..................................................................... Paraonides myriamae

11. Nuchal organs as the only ciliary grooves on prostomium; frontal antenna always absent............................12

- Nuchal organs accompanied by secondary ciliary organs; frontal antenna usually present............................15

12. Modified neurochaetae as curved spines; prostomium without accessory ciliary bands.............................. 13

- Modified neurochaetae as strongly curved hooks bearing subdistal sheath; prostomium with accessory ciliary bands............................................................................................... Paraonis fulgens

13. Modified neurochaetae as short and strongly curved hooks; 3–5 pairs of short branchiae.................. Levinsenia flava

- Modified neurochaetae as long, gently curved hooks; branchiae longer than body width............................14

14. Modified neurochaetae without a ridge on the convex edge; pigmented areas surrounding nuchal organs; branchiae very long (about seven times as long as wide)........................................................ Levinsenia oculata

- Modified neurochaetae bearing a ridge on the convex edge, without pigmented areas surrounding nuchal organs; branchiae moderately long (about four times as long as wide)............................................. Levinsenia gracilis

15. Modified neurochaetae hooked with subterminal spine on concave side of stem; frontal antenna articulate..............16

- Modified neurochaetae otherwise; frontal antenna smooth if present............................................17

16. Frontal antenna long, multiarticulate.................................................. Aricidea (Aricidea) wassi

- Frontal antenna short, with only one articulation........................................ Aricidea (Aricidea) minuta

17. Postbranchial neuropodia bearing capillaries clearly thicker than corresponding notochaetae together with modified chaetae1 8

- Postbranchial neuropodia bearing capillaries similar to corresponding notochaetae together with acicular modified chaetae.23

18. Frontal antenna absent.................................................. Aricidea (Strelzovia) parabelgicae n. sp.

- Frontal antenna present................................................................................ 19

19. Modified neurochaetae abruptly tapering, with slender terminal spine...................... Aricidea (Strelzovia) suecica

- Modified neurochaetae gradually tapering, terminal spine as continuation of tip or absent...........................20

20. Ventral-most modified neurochaetae clearly thicker and more strongly curved than the rest; frontal antenna reaching beyond posterior end of chaetiger 2................................................... Aricidea (Strelzovia) quadrilobata

- All modified neurochaetae similar in thickness; frontal antenna shorter..........................................21

21. Dorsal podial lobes of chaetiger 1 similar in length to those of remaining prebranchial chaetigers; branchiae relatively thin, cylindrical and gradually tapering; notopodial postchaetal lobes of postbranchial region threadlike and bearing a minute distal swelling................................................................... Aricidea (Strelzovia) albatrossae

- Dorsal podial lobes of chaetiger 1 clearly shorter than those of remaining prebranchial chaetigers; branchiae flask shaped and abruptly tapering at least on posterior half of branchial region; notopodial postchaetal lobes of postbranchial region without distal swelling.......................................................................................22

22. Prostomium slightly longer than wide; frontal antenna similar in width all along and with rounded tip; branchiae erect, longer than body width and bearing a long filamentous tip in posterior branchial region.............. Aricidea (Strelzovia) roberti

- Prostomium triangular and clearly wider than long; frontal antenna with wider base and tapering tip; branchiae lying over dor- sum, shorter than body width, tapering through complete branchial region................. Aricidea (Strelzovia) hartmani

23. Acicular modified neurochaetae without terminal spine.......................................................24

- Acicular modified neurochaetae with terminal spine.........................................................25

24. Tip of stem strongly curved and bearing hood; prostomium elongate and round in front; antenna inserted on posterior half of prostomium reaching anterior margin of chaetiger 1...................................... Aricidea (Acmira) cerrutii

- Tip of stem gently curved and without hood; prostomium wider than long and triangular; antenna inserted on anterior half of prostomium and never reaching chaetiger 1............................................ Aricidea (Acmira) simonae

25. Prostomium as equilateral triangle; frontal antenna directed posteriorly and reaching up to posterior end of chaetiger 2; bran- chiae in posterior branchial region ending in a long filament; modified neurochaetae with stem tip covered by a fine hood................................................................................. Aricidea (Acmira) catherinae

- Prostomium longer than wide; frontal antenna short and barely reaching chaetiger 1; branchiae in posterior branchial region tapering evenly, modified neurochaetae with stem tip fringed with fine hairs.................. Aricidea (Acmira) laubieri