Fittkau, 1962
Body
Medium sized larvae with a length up to 10 mm. Living larvae are red. No fringe of swimming hairs.
Head
The head is 0.7 - 0.8 mm long and about 1.5 times longer than wide with a cephalic index of 65 - 70 (Moller Pillot, 1984a).
Antenna
The antennal segments are all yellow and the antennal ratio is 2 - 3. The ring organ is situated at 0.5 - 0.6 of the height of the first segment. The second segment is normal and lacks a tuning fork (Wiederholm, 1983; Moller Pillot, 1984a).
Mentum
Dorsomentum without teeth.
Ligula and paraligula
Ligula with 5 brown teeth in a concave row. Paraligula with a long outer and a small inner tooth
Mandible
The mandible has a very large basal tooth and accessory tooth is very small Nat mandible.
Maxilla
The maxilla is short with an undivided basal segment.
Anal tubules
4 anal tubules which are longer than wide.
Posterior parapods
All claws on posterior parapods are yellow. No teeth on their inner margin longer claws at the most finely serrate Nat claws.
Differential characteristics
The concave ligula, mandible with a very large basal tooth separate Natarsia and Krenopelopia from all other Tanypodinae. Natarsia has a cephalic index of 65-70% and a very small inner mandibular tooth Nat mandible, while the cephalic index of Krenopelopia is 55-65% and the inner tooth is distinct Kre mandible.
Diversity
European species: 2
Treated species: 0