Kieffer, 1909
Body
Small larvae up to 4 mm long. Living larvae are pale and only the thorax with light purple stains. The anterior and posterior parapods are separate and bear rows of claws. Procercus short and weakly sclerotized, without a spur and with setae which are about 10 x as long as the procercus. Supra-anal setae are also very long Thienemannia gracilis anal seg. The two pairs of anal tubules are present (Wiederholm, 1983; Moller Pillot, 1984b).
Head
The head length is 0.27-0.30 mm (Moller Pillot, 1984b).
Antenna
The antenna consists of five segments. Segment 3 shorter than segment 4. The blade is subequal to the flagellum. Lauterborn organs are conspicuous.
Mentum
The mentum has two median teeth which are lower than (T. gracilis) of as high as (T. spec.) the first lateral teeth. Five pairs of lateral teeth. The ventromental plates are weak and the beard is absent Thienemannia gracilis mentum.
Labrum
The pecten epipharyngis consists of three short scales, SI is plumose, labral lamellae present (T. gracilis) Thienemannia gracilis labrum or absent (T. spec.) and the premandible has two apical teeth and two inner teeth (Wiederholm, 1983; Moller Pillot, 1984b).
Mandible
The mandible has an apical tooth and 3 (T. spec.) or 4 (T. gracilis) inner teeth. The seta interna has smooth to weakly serrate branches (Wiederholm, 1983).
Differential characteristics
Thienemannia can be separated from all genera except Metriocnemus by the mentum with 5 pairs of lateral teeth and the weak ventromental plates Thienemannia gracilis mentum, antenna 5 segmented, plumose SI Thienemannia gracilis labrum, mandible with 4-5 teeth. Thiemannia can be separated from Metriocnemus Metr scirpi anal segments by the short and weakly sclerotized procercus with long setae Thienemannia gracilis anal seg.
Diversity
European species: 3
Treated species: 0