(Goetghebuer, 1942)
Body
Medium sized larvae up to 7 mm long. The anterior and posterior parapods are separate and bear rows of claws. The procercus is present but the anal tubules are absent (Wiederholm, 1983; Moller Pillot, 1984b).
Head
Antenna
The antenna consists of five segments. The blade is shorter than the flagellum. Lauterborn organs are absent or not visible (Hirvenoja, 1973).
Mentum
The mentum has one very wide median tooth and 6 pairs of lateral teeth. The median tooth is flat or slightly concave. The ventromental plates are narrow. The beard is very long Halocl Psammo mentum (Hirvenoja, 1973; Wiederholm, 1983; Moller Pillot, 1984b).
Labrum
The pecten epipharyngis consists of three scales, SI is plumose and the premandible has 3-5 teeth (Wiederholm, 1983; Moller Pillot, 1984b).
Mandible
The mandible has an apical tooth and 3 inner teeth. The seta interna has serrate branches (Wiederholm, 1983).
Differential characteristics
In brackish water the combination of missing anal tubules and shape of the mentum are distinctive for H. braunsi Halocl Psammo mentum.