Kieffer in Bause, 1913
Body
Small larvae up to 3-4 mm long in a transportable straight case Stempellinella case. The posterior parapods bear only simpel claws (Brundin, 1948; Wiederholm, 1983).
Head
The S3 is simpel.
Antenna
The antenna stands on a tall pedestal with a large apical projection and consists of 5 segments. The basal segment is subequal to the flagellum. Segment 2 is longer than the combined following segments and bears alternating large proximal and distal Lauterborn organs on small pedestals. The distal pedestal not reaching further than the middle of the 4th segment Zavrelia antenna.
Mentum
The mentum has a simpel median tooth and 6 pairs of lateral teeth. The median and first laterals are basally fused Zavrelia mentum. The ventromental plates are widely separated and not as wide as the mentum.
Labrum
SI is a comb and labral lamellae form a single plate with numerous apical teeth. The pecten epipharyngis consists of 3 very small scales with distal teeth Zavrelia pe three small scales. The premandible has 4 apical teeth.
Mandible
The mandible with a dorsal tooth, apical tooth and 3 inner teeth, all pale. The pecten mandibularis is present and seta interna with branches.
Differential characteristics
Of all Tanytarsini only Stempellinella and Zavrelia have alternate Lauterborn organs Stempellinella alternate LO. Zavrelia can be separated from Stempellinella by the antennal blade reaching far beyond the tip of the antenna Zavrelia antenna, while in Stempellinella the blade reaches only slightly beyond the antenna (lauterborn organs included) Stempellinella ant both. Also a premandible with 4 sharp apical teeth Zavrelia labrum pe premand (2-3 apical teeth and a blunt inner tooth in Stempellinella Stempellinella labrum pm pe) and the pecten epipharyngis with 3 very small scales Zavrelia pe three small scales (3 long slender scales in Stempellinella Stempellinella labrum pm pe) are distinctive.