Eulagisca macnabi is a scale worm that occurs in the Antarctic Ocean, the Amundsen Sea and off the South Orkney Islands at depths of about 300 to 1500m.

[2] Eulagisa macnabi most likely has 15 pairs of elytra that have a marginal fringe of papillae.

It is brown-pigmented, especially on bases of parapodia and elytrophores.

Lateral antennae are inserted terminally on anterior margin of prostomium.

The notochaetae are distinctly thicker than the neurochaetae, but bidentate neurochaetae are absent.