Melinna cristata can be up to 69 mm long. It can be found along the entire Norwegian coast, at Svalbard and in the Barents Sea at depths between 40 and 550 meters.

Type locality

Bergen or Finnmark, Norway. Neotype from Hjeltefjorden, Norway, 60o36.882’N 4o51.853’E, 78 m.

Key characters

Fig. 1. Anterior end, dorsolateral view Arrow denotes postbranchial hook

Fig 2. Anterior end, dorsal view. Dorsal crest serrated.

Measurements: Up to 69 mm long.

Number of thoracic chaetigers: 18

Number of thoracic uncinigers: 14

Number of abdominal uncinigers: Up to 49–57.

Prostomium: With well-defined anterior and posterior parts, separated by pair of deep transverse nuchal grooves that nearly meet mid-dorsally; small cluster of tiny eyespots in median area of prostomium.

Mouth tentacles: Numerous, equally sized and smooth.

Branchiae: Four pairs in two basally fused groups; three branchiae in each group in oblique row slanting posteriorly towards mid-dorsum, fourth branchia in front of the middle one of the three; less than 20% of branchial length of inner- and anteriormost branchiae in each group fused together; branchiae within each group fused to similar extent.

Postbranchial hooks: Narrow base and gently curved tip.

Postbranchial depression: Wide.

Dorsal crest: With serrations equal in size.

Special features: Abdomen with prominent ciliated rudimental notopodia.

Pygidium: One pair of large dorsal lobes and 2–4 indistinct smaller ventral lobes.

Tube: Thin layer of organic secretion incrusted with mud without shell fragments attached.

Distribution

Entire Norwegian coast, Svalbard, Barents Sea; 40–550 m (Mackie and Pleijel 1995).

Similar species

Melinna cristata can easily be separated from Melinna albicincta and Melinna elisabethae by the gently curved tips of the postbranchial hooks, M. albicincta and M. elisabethae have postbranchial hooks with strongly curved tips. Also, the tubes of M. cristata has no shell fragments attached, whereas both M. albicincta and M. elisabethae have shell fragments attached. Melinna palmata is a species that, so far, has not been confirmed from Norway, but is very similar to M. cristata. Melinna palmata can be separated from M. cristata by the absence of neurochaetae on the fourth thoracic chaetiger and the scalloped dorsal crest, whereas M. cristata has serrated dorsal crest.

Sources

Mackie ASY og Pleijel F (1995). A review of the Melinna cristata-species group (Polychaeta: Ampharetidae) in the northeastern Atlantic. Mitteilungen aus dem Hamburgischen zoologischen Museum und Institut 92: 103-124.

Personal observations, Alvestad T.