Fittkau, 1962
Body
Medium sized larvae with a length up to 10 mm. Living larvae are yellowish white. The fringe of swimming hairs is absent (Wiederholm, 1983; Moller Pillot, 1984a).
Head
The head length is 1,05 - 1,3 mm (1,178 mm in a specimen measured by M. Rieradevall) with a cephalic index of 65 - 75% (Moller Pillot, 1984a).
Antenna
The antennal segments are all yellow and the antennal ratio is about 5. The ring organ is situated at 0.4 - 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 much smaller inner tooth Arctopel ligula paraligula.
Mandible
The mandible has a small basal tooth Arctopel mandible.
Maxilla
The maxilla is short with a single basal segment. The b-seta has 2 segments Arctopel maxilla b-seta.
Anal tubules
4 anal tubules which are longer than wide.
Posterior parapods
The claws on posterior parapods are all yellow and without inner teeth.
Differential characteristics
Arctopelopia is closely related to Conchapelopia, Rheopelopia and Thienemannimyia. Their common characters are:
dorsomental teeth absent
concave ligula Arctopel ligula paraligula
small basal tooth of mandible Arctopel mandible.
Arctopelopia differs from the other genera by:
a higher cephalic index (65 -75 vs 55 - 65)
ring organ lower on first antennal segment (0.4 - 0.6 vs 0.6 - 0.75)
Diversity
European species: 3
Treated species: 0