Pagast, 1947
Body
Medium sized larvae up to 7 mm long. Body setae pale and indistinct. The anterior and posterior parapods are separate and bear rows of claws. Procercus is shorter than wide, with 5-7 anal setae and 2 subapical seta. Two pairs of anal tubules present (Wiederholm, 1983).
Head
Antenna
The antenna consists of five segments. Segment 5 longer than segment 4. Segment 3 is annulated. Lauterborn organs are present.
Mentum
The mentum has one median tooth and 8-10 pairs of lateral teeth. The middle and first lateral teeth are yellow the remaining lateral teeth are brownish. The ventromental plates are large covering some lateral teeth Sympott mentum.
Labrum
The pecten epipharyngis consists of three long pointed scales, SI is simpel and labral lamellae weak and probably with 2 transparent lobes Sympott labrum. The premandible has 1 large apical tooth, 2-3 inner teeth and a lateral spine (Wiederholm, 1983).
Mandible
The mandible has an apical tooth and 4 inner teeth. The seta interna with appr. 12-21 smooth to serrated branches (Wiederholm, 1983).
Differential characteristics
Living in cool springs, a mentum with 8-10 pairs of lateral teeth, large ventromental plates Sympott mentum and simpel SI Sympott labrum separates Sympotthastia from all other Orthocladiinae except Potthastia gaedii which has a much broader middle tooth and does not live in springs but in rivers.
Diversity
European species: 3
Treated species: 0