Kieffer, 1918
Body
Medium sized to large larvae up to 11 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 5-6 anal and 2 subapical setae Syndiam hygrop procercus. Two pairs of anal tubules present (Wiederholm, 1983).
Head
Antenna
The antenna consists of five segments. Segment 3 longer than segment 2 and segment 5 longer than segment 4. Segment 3 is annulated and lauterborn organs are present.
Mentum
The mentum has one or two median teeth and 9-10 pairs of lateral teeth. The ventromental plates are weak Syndiam hygrop mentum.
Labrum
The pecten epipharyngis consists of five broad scales, SI is simpel and labral lamellae are numerous with bifid apices. The premandible has 6 apical teeth and a lateral spine (Wiederholm, 1983).
Mandible
The mandible has an apical tooth and 4-5 inner teeth. The seta interna has 22-25 serrated branches (Wiederholm, 1983).
Differential characteristics
Living in flowing water, a mentum with 9-10 pairs of lateral teeth Syndiam hygrop mentum, weak ventromental plate and simpel SI separates Syndiamesa and Diamesa from all other Orthocladiinae s.l.
Syndiamesa is characterized by a procercus not being reduced, with 5-7 anal setae and 2 subapical setae Syndiam hygrop procercus.
Diversity
European species: 4
Treated species: 0