Spaerck, 1923
Body
Small larvae up to 4 mm long. Living larvae are pale. The L4 setae on the body are simpel. The anterior and posterior parapods are separate and bear rows of claws. Procercus and two pairs of anal tubules are present (Wiederholm, 1983; Moller Pillot, 1984b).
Head
The head length is 0.3 mm with the frontal half much darker than the basal section Heterotan head dorsal (Moller Pillot, 1984b).
Antenna
The antennae are as long as the head and mounted on a pedestal Heterotan head dorsal (like Tanytarsini) and consists of four segments. The blade is slightly shorter than the flagellum. Lauterborn organs are very large and arise at different levels of segment 2.
Mentum
The mentum has two median teeth and 6 pairs of lateral teeth. The inner two pairs are shorter than the second lateral pair. The ventromental plates are large and cover some teeth. The beard is absent Heterotan apicalis mentum.
Labrum
The pecten epipharyngis consists of three small scales, SI is plumose and the premandible has four teeth (Wiederholm, 1983; Moller Pillot, 1984b).
Mandible
The mandible has an apical tooth and 3 inner teeth. The seta interna has plumose branches (Wiederholm, 1983).
Differential characteristics
The long antenna mounted on a pedestal is distinctive for Heterotanytarsus apicalis Heterotan head dorsal.
Diversity
European species: 2
Treated species:
Heterotanytarsus apicalis