Magelonidae, Cunningham & Ramage, 1888

Mortimer, Kate, Mills, Kimberley, Jordana, Esther, Pinedo, Susana & Gil, João, 2020, A further review of European Magelonidae (Annelida), including redescriptions of Magelona equilamellae and Magelona filiformis, Zootaxa 4767 (1), pp. 89-114 : 111

Key to adult Magelonidae species in European waters

(adapted from Mortimer et al. 2011 and Fiege et al. 2000)

1. Specimens with eight thoracic chaetigers........................................ Octomagelona bizkaiensis ( Fig. 12 )

- Specimens with nine thoracic chaetigers............................................................2 ( Fig. 11 )

2. Chaetiger 9 carrying specialised chaetae with mucronate tips................................................... 3

- Chaetiger 9 without specialised chaetae.................................................................... 4

3. Lateral pouches present between chaetigers 10 and 11. Notopodial postchaetal lamellae of chaetigers 1–8 with crenulate upper margins; superior dorsal lobes present on chaetigers (3) 4–8.................................... Magelona johnstoni

- Lateral pouches not occurring until extreme posterior region. Thoracic notopodial postchaetal lamellae with smooth upper margins; no superior dorsal lobes on thoracic chaetigers........................................ Magelona mirabilis

4. Abdominal hooks bidentate, small, slender species........................................................... 5

- Abdominal hooks tridentate............................................................................. 6

5. Prostomium without prostomial horns, superior dorsal lobes absent................................. Magelona minuta

- Prostomial horns, superior dorsal lobes present on thoracic chaetigers........... Magelona sp. Mud Volcano, Gulf of Cádiz

6. Prostomium with clearly distinct frontal horns.............................................................. 7

- Prostomium without frontal horns, or with a squared anterior margin (“rudimentary horns”).......................... 8

7. Prostomium wider than long, anterior margin crenulate. Thoracic superior dorsal lobes foliaceous........ Magelona wilsoni

- Prostomium longer than wide, anterior margin smooth. Thoracic superior dorsal lobes slender......... Magelona lusitanica

8. Slender species; prostomium longer than wide, superior dorsal lobes present on chaetigers 1–8. Thoracic transverse bands just behind parapodia present................................................................ Magelona filiformis

- Stout species; prostomium width equal to/or slight larger than length. No thoracic superior dorsal lobes. Thoracic pigment band between chaetigers 5–9 (N.B. fades in preserved specimens). Sediment covered paper-like tube may be present........... 9

9. Abdominal notopodial lateral lamellae much larger than neuropodial. Neuropodial lamellae of posterior thorax ventral beneath chaetal bundle............................................................................ Magelona alleni

- Abdominal lateral lamellae of roughly equal size in both rami. Neuropodial lamellae of posterior thorax in a distinctly postchaetal position..................................................................... Magelona equilamellae

Figures

FIGURE 11. European Magelona species: M. minuta, M. filiformis, M. lusitanica, M. johnstoni, M. mirabilis, M. alleni, M. equilamellae and M. wilsoni (adapted from Mills & Mortimer 2018; Mortimer & Mackie 2014 and Mills & Mortimer 2019a and current study (M. lusitanica, paratype NMW.Z.2010.010.0004; M. wilsoni, NMW.Z.2010.010.0008)). (Photos of M. johnstoni, M. mirabilis, M. alleni by Andrew Mackie).

FIGURE 12. Octomagelona bizkaiensis, holotype (MNCN 16.01/6887). Anterior (dorsal view).