Fries, 1830
Body
Medium sized larvae up to 9 mm long. Living larvae are grayish-green (in H. lugubris). The anterior and posterior parapods are separate and bear rows of claws. Procercus and two pairs of anal tubules present (Wiederholm, 1983; Moller Pillot, 1984b).
Head
The head length is 0.4 - 0.6 mm (H. lugubris and H. pilipes) (Moller Pillot, 1984b).
Antenna
The antenna consists of six segments. The blade is shorter than the flagellum. Lauterborn organs are conspicuous.
Mentum
The mentum has two median teeth and 6 pairs of lateral teeth. The ventromental plates are well developed. The beard is absent Hydrob lugubris mentum.
Labrum
The pecten epipharyngis consists of three spines, SI is plumose Hydrob pilipes labrum and the premandible has two apical teeth and one inner tooth (Wiederholm, 1983; Moller Pillot, 1984b).
Mandible
The mandible has an apical tooth and 3 inner teeth. The seta interna has simpel branches (Wiederholm, 1983).
Differential characteristics
The combination of the antenna with 6 segments and the mentum with 6 pairs of lateral teeth are characteristic for Hydrobaenus Hydrob lugubris mentum, Trissocladius and Zalutschia. Trissocladius has a mentum with median teeth lower than the first laterals Trissocl brevipalpis mentum (higher in Hydrobaenus) and Zalutschia has a small beard Zalut gr. mucronata mentum (absent in Hydrobaenus).
Diversity
European species: 9
Treated species:
Hydrobaenus distylus
Hydrobaenus lugubris
Hydrobaenus pilipes