(Fabricius, 1787)
Body
Medium sized larvae with a length up to 11 mm. Living larvae are grayish-green. The fringe of swimming hairs is present (Wiederholm, 1983; Moller Pillot, 1984a).
Head
The head has a length of 0.70 - 0.85 mm, with a cephalic index of 90 - 100 (Wiederholm, 1983; Moller Pillot, 1984a).
Antenna
The antennal segments are all yellow and the antennal ratio is about 6.3. The ring organ is situated at 0.8 - 0.9 of the height of the first segment. The second segment is normal and lacks a tuning fork (Wiederholm, 1983; Moller Pillot, 1984a).
Mentum
Dorsomentum with 6 - 8 large teeth on each side.
Ligula and paraligula
Ligula yellow with 4 equal teeth in a straight line. Paraligula composed of a number of simpel and branched spines Pse ligula dorsomentum.
Mandible
The mandible has a large basal tooth. The inner margin with saw-like row of smaller teeth Pse mandible (Wiederholm, 1983; Moller Pillot, 1984a).
Maxilla
The maxilla short and the basal segment is not divided.
Anal tubules
4 anal tubules which are longer than wide.
Posterior parapods
All claws on posterior parapods are yellow and bear no teeth on their inner margin.
Differential characteristics
The yellow ligula with four teeth Pse ligula dorsomentum and the saw-like inner margin of the mandible Pse mandible are distinctive.