Flabelligeridae de Saint-Joseph 1894

Key to genera of Flabelligeridae de Saint-Joseph, 1894

1 Anterior end with chaetae; branchiae variable............................................................... 2

- Anterior end without chaetae or parapodia; branchiae in a single series (pelagic worms)............................................................................................ Poeobius Heath, 1930 (see Salazar-Vallejo 2008)

2(1) Cephalic cage exposed, well developed (chaetiger 1 with thick, rigid chaetae, at least twice as long as body width)........ 3

- Cephalic cage covered by tunic or poorly developed (chaetiger 1 with chaetae usually shorter than body width; if longer, then thin, flexible)........................................................................................ 17

3(2) Tunic thick, often covering most individual papillae, at least along anterior chaetigers............................... 4

- Tunic thin, most papillae visible, exposed................................................................. 9

4(3) Chaetiger 2 markedly longer than following ones, sometimes with a constriction towards its posterior margin............ 5

- Chaetiger 2 as long as neighbouring chaetigers.............................................................. 7

5(4) Tunic without sediment; all chaetigers with long multiarticulate spines; anterior end with one pair of trifid organs (pelagic worms)............................................ Buskiella McIntosh, 1885 (see Salazar-Vallejo & Zhadan 2007)

- Tunic with sediment, sometimes with large tubercles; median and posterior chaetigers with short neurochaetae; anterior end with palps and branchiae, without trifid organs............................................................. 6

6(5) Anterior chaetigers (3–7) with pseudo-compound neurochaetae................................................................................................ Therochaeta Chamberlin, 1919 (partim) (see Salazar-Vallejo 2013a)

- Anterior chaetigers (3–7) without pseudocompound neurochaetae, with anchylose hooks or multiarticulate chaetae.............................................................................. Paratherochaeta Salazar-Vallejo, 2013

7(4) Posterior chaetigers with articulate neurochaetae............................................................. 8

- Posterior chaetigers with anchylose neurochaetae, sometimes bifid, bidentate or subdistally expanded; tunic with variable amounts of sediment particles................................ Trophoniella Hartman, 1959 (see Salazar-Vallejo 2012c)

8(7) Tunic with sediment particles; median and posterior chaetigers with multiarticulate neurochaetae, often bidentate...................................................................... Piromis Kinberg, 1867 (see Salazar-Vallejo 2011b)

- Tunic without sediment particles; median chaetigers with multiarticulate neurochaetae, posterior chaetigers with oligoarticu- late neurochaetae............................................ Pycnoderma Grube, 1877 (see Salazar-Vallejo 2011b)

9(3) Sediment particles concentrated into discrete shields or crusts................................................. 10

- Sediment particles not concentrated into discrete shields or crusts, sometimes forming sediment tubercles; body papillae vari- able............................................................................................... 12

10(9) Body papillae long, with or without sediment; anterior chaetigers with segments partly or totally covered by sediment particles.............................................. Therochaeta Chamberlin, 1919 (partim) (see Salazar-Vallejo 2013a)

- Body papillae short, without sediment, anterior chaetigers with sediment particles arranged as a dorsal shield............ 11

11(10) Anterior chaetigers with pseudocompound neurochaetae; posterior region cylindrical with 2–4 neurochaetae in transverse series.................................................. Semiodera Chamberlin, 1919 (see Salazar-Vallejo 2012b)

- Anterior chaetigers with multiarticulated neurochaetae; posterior region often depressed with 5–8 neurochaetae in longitudinal series..................................................................... Daylithos Salazar-Vallejo, 2012b

12(9) Median chaetigers with long multiarticulate neurospines...................................................................................................... Diplocirrus Haase, 1915 (see Salazar-Vallejo & Buizhinskaja 2011)

- Median chaetigers with anchylose, falcate neurospines, may be very short........................................ 13

13(12) Median and posterior neurochaetae longer than papillae...................................................... 14

- Median and posterior neurochaetae small, as long as or shorter than papillae; papillae abundant, giving a velvet or granulose appearance; branchial filaments abundant, on two lateral peduncles..................................................................................................... Stylarioides delle Chiaje, 1830 (see Salazar-Vallejo 2011a)

14(13) Body papillae thin, abundant, giving a pilose appearance; 8–16 branchial filaments, sessile on branchial plate.................................................................... Ilyphagus Chamberlin, 1919 (see Salazar-Vallejo 2012d)

- Body papillae thick, giving a tuberculate appearance, at least anteriorly.......................................... 15

15(14) Branchial plate with 8 filaments, sessile................................................................... 16

- Branchial plate with two branchial peduncles, each with many filaments in transverse series.................................................................................................... Treadwellius Salazar-Vallejo, 2011

16(15) Median neurochaetae falcate, blunt, shorter than body width.................................... Pherusa Oken, 1807

- Median neurochaetae foliose, tapered, as long as or longer than body width.............. Lamispina Salazar-Vallejo, 2014

17(2) Chaetiger 1 with chaetae in a long, almost continuous series; neurochaetae oligo-articulate with falcate crest............ 18

- Chaetiger 1 with chaetae in short separate bundles; median neurochaetae anchylose................................ 23

18(17) Dorsal papillae completely covered by a more or less continuous tunic.......................................... 19

- Dorsal papillae visible, individually or forming large sediment particles, not covered by tunic........................ 22

19(18) Notochaetae as long as body width or shorter, articulate (at least along half their length); successive notopodia positioned at the same level; cephalic cage chaetae covered by a thin tunic or by series of papillae, without thick tunic.................. 20

- Notochaetae twice as long as body width (including tunic), most anchylose (articles restricted to chaetal distal regions); suc- cessive notopodia arranged in triads, in different level; cephalic cage chaetae covered by a thick tunic........................................................................................... Flabegraviera Salazar-Vallejo, 2012a

20(19) Neuropodial hooks with thick, falcate, entire crests.......................................................... 21

- Neuropodial hooks with thin, tapered mucronate crests, apparently articulate; body with a thin tunic.............................................................................................. Annenkova Salazar-Vallejo, 2012a

21(20) Median notopodia dorsolateral or lateral; anterior end truncate......... Flabelligera Sars, 1829 (see Salazar-Vallejo 2012a)

- Median notopodia ventrolateral; anterior end tapered............................. Flabehlersia Salazar-Vallejo, 2012a

22(18) Notopodial lobes perpendicular to body axis, large, covering notochaetae; median neuropodia lateral........................................................................... Flabelliderma Hartman, 1969 (see Salazar-Vallejo 2007)

- Notopodial lobes longitudinal to body axis, short, fan-shaped, not covering notochaetae; median neuropodia ventral............................................................................... Flabesymbios Salazar-Vallejo, 2012a

23(17) Neurochaetae aristate spines; branchiae usually abundant filaments......................... Bradabyssa Hartman, 1967

- Neurochaetae blunt, falcate spines; branchiae only 8 cirriform filaments......................... Brada Stimpson, 1853