Spionidae

Radashevsky, Vasily I., 2012, Spionidae (Annelida) from shallow waters around the British Islands: an identification guide for the NMBAQC Scheme with an overview of spionid morphology and biology, Zootaxa 3152, pp. 1-35 : 29

Key to genera of Spionidae reported from or likely to be found in shallow waters around Britain and Ireland

1 Branchiae absent. Neuropodia of chaetiger 1 with one or two large crook-like spines in addition to capillaries.... Spiophanes

- Branchiae present. Neuropodia of chaetiger 1 with only capillaries............................................... 2

2(1) Chaetiger 5 with only capillaries.......................................................................... 3

- Chaetiger 5 with heavy spines in addition to capillaries....................................................... 15

3(2) Branchiae beginning after chaetiger 10, limited to middle and posterior chaetigers. One pair of dorsal appendages (horns) present on chaetiger 2 in males. Pygidium with two pairs of cirri......................................... Pygospio

- Branchiae from chaetigers 1–3 for a variable number of chaetigers. Horns absent on chaetiger 2 in males. Pygidium with cirri or otherwise.......................................................................................... 4

4(3) Branchiae throughout most of body length.................................................................. 5

- Branchiae limited to anterior half of body................................................................. 10

5(4) Head anteriorly conical and distally pointed................................................................. 6

- Head anteriorly wide, truncate to conical but not distally pointed................................................ 7

6(5) Branchiae from chaetiger 1. Lateral gills present. Posterior notopodia with only capillaries....................... Dispio

- Branchiae from chaetiger 2. Lateral gills absent. Posterior notopodia with hooks in addition to capillaries......... Scolelepis

7(5) Branchiae from chaetiger 1.............................................................................. 8

- Branchiae from chaetiger 2....................................................................... Microspio

8(7) Posterior notopodia with hooks in addition to capillaries............................................. Marenzelleria

- Posterior notopodia with only capillaries................................................................... 9

9(8) Prostomium with fronto-lateral horns. Pygidium with more than two pairs of cirri......................... Malacoceros

- Prostomium without fronto-lateral horns. Pygidium with two pairs of cirri...................................... S pio

10(4) Occipital antenna present. Nuchal organs extending beyond chaetiger 3. Branchiae present over most of anterior body Laonice

- Occipital antenna present or absent. Nuchal organs extending over 1–2 anterior chaetigers or absent. Branchiae limited to first 20 chaetigers........................................................................................ 11

11(10) Posterior notopodia with only capillaries.................................................................. 12

- Posterior notopodia with hooks in addition to capillaries...................................................... 13

12(11) Single pair of branchiae on chaetiger 1. Peristomium forming distinct hood enveloping prostomium ventrally and laterally. Dorsal transverse ridge on chaetiger 2. Ventral crests absent............................................ Streblospio

- Four pairs of branchiae on chaetigers 2–5. Peristomium not forming hood around prostomium. Dorsal transverse ridge absent on chaetiger 2. Ventral crests from chaetiger 2..................................................... Laubieriellus

13(11) Prostomium conical with narrow and rounded tip anteriorly. Occipital antenna present or absent on prostomium. Nuchal organs absent......................................................................................... Aonides

- Prostomium broadly rounded to truncate anteriorly. Occipital antenna absent on prostomium. Nuchal organs present...... 14

14(13) Branchiae from chaetiger 3 (2–3 pairs)............................................................... Aurospio

- Branchiae from chaetiger 2 (4–13 pairs)............................................................ Prionospio

15(2) Chaetiger 5 with heavy falcate or aristate spines in neuropodia and only capillaries in notopodia............... Atherospio

- Chaetiger 5 with heavy falcate spines in notopodia and only capillaries in neuropodia.............................. 16

16(15) Hooks in neuropodia from chaetiger 8; upper part of hook shaft with constriction, lower part of hook shaft bent at about right angle. Branchiae from chaetiger 7............................................................. Pseudopolydora

- Hooks in neuropodia from chaetiger 7; upper part of hook shaft with or without constriction, lower part of hook shaft slightly curved. Branchiae from chaetigers 2–10................................................................... 17

17(16) Branchiae from chaetiger 2 (from chaetiger 7 in early juveniles)................................................ 18

– Branchiae from chaetigers 7–10 in all-size individuals....................................................... 19

18(17) Notopodia of chaetiger 5 with heavy falcate spines alternating with bilimbate-tipped companion chaetae....... Boccardiella

- Notopodia of chaetiger 5 with heavy falcate spines and brush-topped spines................................ Boccardia

19(17) Chaetiger 1 with notochaetae. Branchiae from chaetigers 7–10. Hooks accompanied by inferior capillaries at least in anterior neuropodia; upper part of hook shaft without constriction.............................................. Dipolydora

- Chaetiger 1 without notochaetae. Branchiae from chaetiger 7. Hooks not accompanied by inferior capillaries; upper part of hook shaft with constriction...................................................................... Polydora