Eteoninae Bergström, 1914
Mystides Théel, 1879
Mystides sp. 1
Voucher. INFLEX: station 4MFB.
Diagnosis. Very small species; voucher specimen complete; 3mm long and 0.35mm wide (including parapodia) for 30 segments; preserved specimen yellow in colour, only ventral cirri with dark red pigments.
Prostomium subpentagonal, with a pair of large, very faint, red eyes positioned in posterior part of prostomium; with 2 pairs of prostomial appendages, only pair of antennae still attached, bottle shaped, palps missing. Proboscis not observed. Three pairs of tentacular cirri in 1 (on segment 1) + 2 (on segment 2) arrangement (where cirri missing scar observed), cirri bottle-shaped (shape not as pronounced as in antennae), those present of similar lengths.
Dorsal cirri mostly missing, present in some mid-body segments where rounded to ovoid, somewhat inflated, not pigmented, relatively small (not exceeding the tip of neuropodia). Ventral cirri similar to dorsal cirri, ovoid; with patches of dark red pigment. Neuropodia relatively short, conical, chaetigerous lobes, of similar length; with one acicular and up to about 15 chaetae. Chaetae compound spinigers, with slender unidentate blades with thin tips; the rostrum without any pronounced teeth, only series of small, fine serrations. Pygidium rounded, wide lobe, with very small, round, lateral cirri; no other cirri observed.
Remarks. This specimen also shows affinities with genus Nereiphylla, but only 3 pairs of tentacular cirri were confirmed, which approach bottle-shaped form, dorsal cirri are spherical, inflated and ventral cirri are horizontally inserted, suggesting this specimen belongs to genus Mystides. Shirla-stain revealed a possible presence of scar or small median antenna, near the posterior margin of prostomium. Should presence of median antenna be confirmed in subsequent specimens, then generic affiliation is likely with genus Pseudomystides. One species in genus Mystides is known from the region, M. notialis Ehlers, 1913 (see entry Mystides cf. notialis). Falkland Island specimen differs in position, size and colour of eyes and is therefore assigned to a different morphospecies as Mystides sp. 1.
