Kieffer, 1922
Body
Medium sized to large larvae up to 10 mm long. Body setae pale and indistinct. The anterior and posterior parapods are separate and bear rows of claws. Procercus with 5-7 anal and 2 subapical setae (Wiederholm, 1983).
Head
Antenna
The antenna consists of five segments. Segment 5 longer than or as long as segment 4. Segment 3 annulated. Lauterborn organs are small.
Mentum
In P. gaedii group the mentum has one very broad median tooth and 8 pairs of lateral teeth. The middle tooth and the first lateral are pale the remaining laterals are dark. The ventromental plates are large Pot gaedii mentum.
In P. longimana group the mentum and ventromental plates are absent Pot longim mentum.
Labrum
In P. gaedii group the SI is simpel, labral lamellae are broad transparent scales.
The pecten epipharyngis consists of three pointed scales. The premandible is simpel without lateral spine (Wiederholm, 1983).
In P. longimana group SI is simpel labral lamellae are bifid or trifid. Pecten epipharyngis with three pointed scales. Premandible with about 15 teeth and a lateral spine.
Mandible
The mandible has an apical tooth and 3-4 inner teeth. The seta interna with 16-21 serrated branches (P. gaedii group) of seta interna absent (P. longimana group) (Wiederholm, 1983).
Differential characteristics
The Potthastia gaedii group is characterized by the mentum with the broad median and first lateral tooth yellow and the dark 8 pairs of lateral teeth Pot gaedii mentum.
The Potthastia longimana group stands out for having no mentum at all Pot longim mentum.
Diversity
European species: 5
Treated species:
Potthastia gaedii
Potthastia longimana