McIntosh, 1876
Description:
A scale-worm with a body of uniform width. Dorsal and ventral surfaces smooth.
Prostomium bilobed, without peaks, with a median antenna, a pair of lateral antennae, laterally inserted, and a pair of palps. Two pairs of eyes, the anterior pair in front of the line of greatest width, the posterior pair well in front of the rear margin.
First segment bearing chaetae and a pair of dorsal and ventral tentacular cirri. Scales overlap, almost covering the body. The first pair are round, the rest oval to kidney-shaped, with smooth margins and the surfaces with a patch of small tubercles.
Notopodia are small mounds with a ventral acicular ligule and few chaetae. Notopodial chaetae are spinose with blunt tips. Neuropodia well developed with an anterior acicular ligule and few chaetae.
Neuropodial chaetae are spinose with bidentate tips, although the secondary tooth is very small. A few chaetae in lower position have unidentate tips (M. castanea-detail).
Size:
Up to 18 mm for 38 chaetigers.
Colour:
Unknown from living material.
Habitat:
Sublittoral to 200 m, usually associated with echinoderms, mostly Spatangus purpureus or Astropecten irregularis .
Distribution:
Arctic, Northeast Atlantic, Mediterranean, Adriatic, Red Sea, English Channel, North Sea.