1 Two achaetous segments after the prostomium; border between thorax and abdomen indistinct; small worms............. 2
- One achaetous segment after the prostomium; medium-size and large worms; border between thorax and abdomen more or less clear (subfamily Orbiniinae)............................................................................. 3
2 Abdominal segments bear capillaries and possibly forked chaetae in notopodium, capillaries and uncini in neuropodia........................................................................................... Protoariciella spp.
- Abdominal segments bear capillaries and swan-shaped chaetae, no uncini or forked chaetae................................................................................................. Proscoloplos cygnochaetus Day, 1954
3 Prostomium pointed................................................................................... 4
- Prostomium rounded to square in front (Naineris)........................................................... 22
4 Not more than four podal papillae and subpodal or stomach papillae combined on posterior thorax..................... 5
- More than four podal papillae and subpodal or stomach papillae combined on posterior thorax....................... 18
5 No uncini among thoracic neurochaetae; thorax usually rounded in section. No subpodal or stomach papillae on posterior thorax (Leitoscoloplos)................................................................................... 6
- At least some uncini present among thoracic neurochaetae; thorax usually flattened; none to three subpodal papillae on posterior thorax........................................................................................... 8
6 Only one podal papilla on posterior thoracic neuropodia...................................................... 7
- Two podal papillae from neuropodium 10–11; thorax with 18–22 chaetigers; branchiae start from chaetiger 8–9....................................................................................... L. bifurcatus (Hartman, 1957)
7 Branchiae from chaetiger 19–21, short and broadly lamellate on abdomen; abdominal neuropodia uniramous with a conical inner lobe and strongly reduced outer lobe............................................. L. latibranchus Day, 1977
- Branchiae start from chaetiger 12–16; thorax with 13–15 chaetigers; abdominal neuropodia strongly bilobed with inner lobe longer than outer.................................................................. L. bilobatus Mackie, 1987
8 Branchiae from chaetiger 8 or later; abdominal neuropodia with 1–2 thin embedded aciculae; a few, or occasionally up to 4 rows of uncini among thoracic neurochaetae (Scoloplos)...................................................... 9
- Branchiae from chaetiger 5–7; three to five rows of uncini in thoracic neuropodia, capillaries few or absent; abdominal neuropodia with one thick protruding acicula (Leodamas)......................................................... 14
9 Branchiae starting from last thoracic or first abdominal segment, dichotomously branched from mid-abdomen onwards; thorax with 15–18 chaetigers, abdominal neuropodial lobes uniramous............................ S. cylindrifer Ehlers, 1904
- Branchiae not branched............................................................................... 10
10 Posterior thoracic neuropodia bilobed (with two podal papillae), in abdominal chaetigers flange papillae (ventral cirri) present; 20–24 thoracic chaetigers, branchiae from chaetiger 8–9.................. S. dayi Hartmann-Schröder & Hartmann, 1980
- All thoracic neuropodia with one podal papilla; no flange papillae (ventral cirri) in abdomen........................ 11
11 Thorax of 20 or more chaetigers; branchiae starting from chaetiger 8; abdominal neuropodia with two subequal lobes.............................................................................. S. novaehollandiae (Kinberg, 1866)
- Thorax of less than 20 chaetigers........................................................................ 12
12 Thoracic neuropodia bear 2–4 anterior rows of uncini and one row of capillaries; abdominal neuropodia bilobate with subequal lobes; bear capillaries and flail chaetae; in abdominal notopodia capillaries and forked chaetae present. Prostomium with very long pointed tip, 17–20 thoracic chaetigers, branchiae from penultimate thoracic segment................................................................................................ S. acutissimus Hartmann-Schröder 1991
- Thoracic neuropodia with few uncini forming no more than half row; abdominal neuropodia with outer lobes much smaller than inner or completely reduced, no more than 17 thoracic chaetigers.............................................. 13
13 Prostomium short, with sharp or blunt tip; thorax with 13–15 chaetigers; branchiae from chaetiger 14–17 (first or second abdominal chaetiger); anterior abdominal neuropodia weakly bilobed; rudimentary outer lobe rapidly lost so neuropodia become uniramous; abdominal neuropodia with capillaries only, notopodia also bear forked chaetae........ S. normalis (Day, 1977)
- Prostomium long, with sharp tapering tip; thorax with 13–17 chaetigers; branchiae present as minute papillae from chaetiger 9–13; always well developed on first abdominal segment; abdominal neuropodia distinctly biramous with inner lobe longer than outer; bear capillaries and flail chaetae; no forked chaetae in abdominal notopodia........ S. simplex (Hutchings 1974)
14 Thoracic and anterior abdominal notopodial lobes with at least three branches; 17 thoracic chaetigers................................................................................................. L. dendrocirrus (Day, 1977)
- Thoracic and abdominal notopodial lobes not branched...................................................... 15
15 Branchiae from chaetiger 7; 3-4 subpodal papillae in posterior thoracic and anterior abdominal segments............................................................................................. L. fimbriatus (Hartman, 1957)
- Branchiae from chaetiger 6............................................................................ 16
16 No subpodal or stomach papillae on posterior thorax or anterior abdomen; thoracic neuropodia without podal papillae or with one papilla on the last thoracic neuropodia; abdominal neuroaciculae distally curved 90°to 180°......................................................................................... L. australiensis (Hartmann-Schröder, 1979)
- Subpodal papillae present at thorax-abdomen junction....................................................... 17
17 Thoracic neuropodia with one or no podal papillae; one subpodal papillae on last thoracic and anterior abdominal chaetigers; 20–32 thoracic chaetigers; abdominal neuroaciculae straight................................ L. cirratus (Ehlers 1897)
- Posterior thoracic neuropodia with 1–2 podal papillae and 1–2 subpodal papillae, two anterior abdominal chaetigers with two subpodal papillae, next 10–15 with one; thorax with 15–24 chaetigers; abdominal neuroaciculae vary from straight to slightly curved........................................................................... L. johnstonei (Day, 1934)
18 No heavy spines among neurochaetae on posterior thoracic segments (Orbinia)................................... 19
- A few heavy spines (often elongated) among neurochaetae on posterior thoracic segments (Phylo).................... 20
19 Branchiae from chaetiger 8. Thorax with 15–21 chaetigers with a maximum of three podal papillae, ten subpodal and three stomach papillae................................................................... O. hartmanae Day, 1977
- Branchiae from chaetiger 5. Thorax with 26 to 32 chaetigers with about 10 podal papillae and numerous stomach papillae................................................................................. O. papillosa (Ehlers, 1907)
20 Thoracic and anterior abdominal notopodia branched.................................... P. fimbriatus (Moore, 1903)
- Thoracic and abdominal notopodia not branched........................................................... 21
21 Thorax with 16–18 chaetigers; interramal cirrus longer than the neuropodium..................... P. felix Kinberg, 1866
- Thorax with 15 chaetigers; interramal cirrus shorter than the neuropodium.................. P. novazealandiae Day, 1977
22 Two podal papillae on posterior thoracic neuropodia; interramal cirrus present; one bidentate neuroaciculum................................................................................................ N. victoriae Day, 1977
- One podal papilla on all thoracic neuropodia; no interramal cirrus; three to five blunt neuroaciculae................... 23
23 Prostomium rounded in front; 11–19 thoracic chaetigers with branchiae from chaetiger 5–9...... N. laevigata (Grube, 1855)
- Prostomium square in front; 30–38 thoracic chaetigers; branchiae from chaetiger 6............ N. australis Hartman, 1957