(Goetghebuer in Thienemann, 1936)
Body
Medium sized larvae up to 8 mm. The body with stout setae about half as long as the segment. The laterals in pairs. The anterior and posterior parapods are separate and bear rows of claws. Procercus well sclerotized and two pairs of anal tubules present Tvet discoloripes anal segm (Wiederholm, 1983; Moller Pillot, 1984b; Schmid, 1993).
Head
The head length is 0.371 - 0.453 mm (Schmid, 1993).
Antenna
The antenna consists of five segments. The blade reaches the tip of the 5th antennal segment. Lauterborn organs are conspicuous (Cranston, 1982).
Mentum
The mentum has two median teeth and 5 pairs of lateral teeth. The mentum has alternating lighter and darker longitudinal bands due to varying thickness of the chitin. The ventromental plates are weak. The beard is absent Tvet discoloripes mentum.
Labrum
The pecten epipharyngis consists of three scales, SI is plumose Tvet discolor S1 pict and the premandible has one apical tooth (Wiederholm, 1983; Moller Pillot, 1984b; Schmid, 1993).
Mandible
The mandible has an apical tooth and 5 pair of inner teeth. The mola is smooth (Schmid, 1993).
Differential characteristics
Tvetenia can be identified by the stout body setae Tvet discoloripes body setae, mentum with 5 pairs of lateral teeth Tvet discoloripes mentum, weak ventromental plates and SI plumose. Tvetenia differs from Eukiefferiella by having long stout body setae.
Tvetenia discoloripes can be separated from the other Tvetenia species by:
Smooth mola and antennal blade reaching the tip of the 5th antennal segment.