Sigalioninae

Updated key to the species of Sigalioninae in the Northeast Atlantic and Mediterranean Sea

We follow the latest subfamily designation proposed by Gonzalez et al. (2018). For keys to other species currently assigned to the subfamilies Pelogeniinae, Pholoinae and Pisioninae, see Barnich & Fiege (2003), Martinez et al. (2008) and Meissner et al. (2020).

Please note: characters in the key apply to adults; in younger individuals or juveniles there is likely some variation to be observed, for example in the number of stylodes present or the degree of coverage with ventral body papillae. Elytral characters apply to anterior elytra (but not the first pair) unless otherwise stated. The distribution given for species not treated in detail herein is based on Barnich & Fiege (2003), Wehe (2007) and Núñez et al. (2015).

1. Median antenna indistinct or very small, without ceratophore. Outer elytral margin extended into digitiform, papillated processes........................................................................................................ 2

– Median antenna present, with distinct ceratophore. Outer elytral margin straight, smooth (i.e., papillae absent) or straight, papillated (papillae simple or dichotomously branched)..................... 3

2. Elytral marginal processes with about 20 papillae. Large papilla present on anterior side of superior margin of neuropodia (difficult to see in small individuals)........................................................................................................................................ Sigalion mathildae Audouin & Milne Edwards, 1832 (NE Atlantic, Mediterranean; nearshore)

– Elytral marginal processes with about 10 papillae. Without papilla on neuropodia......................................................................................................................... Sigalion squamosus Delle Chiaje, 1830 (NE and SE Atlantic, Mediterranean; nearshore and offshore)

3. Ceratophore of median antenna without auricles............................................................................. 4

– Ceratophore of median antenna with auricles.................................................................................. 5

4. Outer elytral margin with irregularly dichotomously branched papillae, elytral surface smooth........................................................................................................ Euthalenessa oculata (Peters, 1854) (NE Atlantic: south of Channel to S Africa, Mediterranean, Indian Ocean; nearshore and offshore)

– Elytral margin and surface smooth..................................................... Leanira hystricis Ehlers, 1874 (NE and SE Atlantic, Mediterranean; nearshore and offshore)

5. Pair of dorsal cirri present on segment 3......................................................................................... 6

– Dorsal cirri absent on segment 3..................................................................................................... 7

6. Neurochaetae all spinigers. Outer elytral margin with numerous filiform papillae, elytral surface smooth..................................................................................... Neoleanira tetragona (Örsted, 1845) (Arctic, NE and SE Atlantic; offshore)

– Neurochaetae spinigers and falcigers. Outer elytral margin with several filiform papillae, elytral surface smooth.................................................................... Eusthenelais hibernica McIntosh, 1876 (NE Atlantic: Norway, western British Isles and Ireland, to SW Portugal; offshore)

7. Lateral lips of mouth with obvious labial lobes. Neurochaetae all spinigers. Elytral margin and surface smooth..................................................................... Labioleanira yhleni (Malmgren, 1867) (NE Atlantic: south of Channel to W Africa, Mediterranean, Indian Ocean; nearshore and offshore)

– Mouth without labial lobes. Neurochaetae only falcigers or falcigers and spinigers, sometimes a few simple, spinous neurochaetae also present...................................................................................... 8

8. Ventral body surface and parapodial stylodes distinctly papillated................................................. 9

– Ventral body surface and parapodial stylodes smooth (occasionally with minute papillae in parapodia of juveniles or in anteriormost parapodia of adults)....................................................................... 10

9. Ventral body surface densely papillated. Neuropodial posterior bracts truncate. Outer and posterior elytral margin with numerous short papillae, elytral surface covered by rounded to conical microtubercles......................................................... Fimbriosthenelais zetlandica (McIntosh, 1876) (NE and SE Atlantic, Mediterranean, Indian Ocean; nearshore and offshore)

– Ventral body surface finely papillated. Neuropodial posterior bracts bilobed. Outer elytral margin with filiform papillae, elytral surface with rounded to conical microtubercles (in anterior elytra surface completely covered, in middle and posterior elytra microtubercles confined to areas near margins)...................................................................... Fimbriosthenelais longipinnis (Grube, 1869) (E Mediterranean, Red Sea, Indo-Pacific; nearshore)

10. Outer elytral margin with irregular extensions (anterior elytra) or notched (posterior elytra); elytral surface smooth, except for some microtubercles near anterior margin. Parapodial stylodes slender, cirriform; notopodia with few long dorsal papillae; margins of anterior neuropodial bracts smooth. Notochaetae tapering to simple capillary tip................................ Sthenelais limicola (Ehlers, 1864) (NE, NW and SE Atlantic, Mediterranean; nearshore and offshore)

– Outer elytral margin straight, with filiform papillae; elytral surface covered by conical microtubercles. Parapodial stylodes more or less club-shaped; notopodia without long dorsal papillae; margins of anterior neuropodial bracts with digitiform extensions. Notochaetae tapering to simple or minutely bidentate capillary tip...................................................................... Sthenelais boa (Johnston, 1833) (NE Atlantic, Mediterranean, Indo-Pacific; nearshore)