Fittkau, 1962
Body
Medium sized larvae with a length up to 8 mm. Living larvae are brownish. No fringe of swimming hairs.
Head
The head length is 0.70 - 0.86 mm with a cephalic index of 45 - 50 (Moller Pillot, 1984a).
Antenna
The antennal ratio is about 3. The ring organ is situated at 0.4 - 0.6 of the height of the first segment. The second segment is brown with a U shaped process distally, the tuning-fork Xen tuningfork (Wiederholm, 1983; Moller Pillot, 1984a).
Mentum
Dorsomentum without teeth.
Ligula and paraligula
Ligula with 5 brown teeth in a straight row. Paraligula with a long outer and a smaller inner tooth Xen ligula paraligula.
Mandible
The mandible has a large basal and prominent accessory tooth Xen mandible.
Maxilla
The maxilla is short with an undivided basal segment.
Anal tubules
4 anal tubules which are longer than wide.
Posterior parapods
Some claws on posterior parapods may be brown. Three yellow claws with teeth on their inner margin Xen claws.
Differential characteristics
In the Pentaneurini Xenopelopia and Paramerina (cingulata) share the combination of straight ligula Xen ligula paraligula, large basal mandibular tooth Xen mandible and brown second antennal segment. Xenopelopia is separated from Paramerina by the larger head length (0.70 - 0.86 vs 0.50 - 0.70 in Paramerina), smaller cephalic index (45 - 50% vs 50 - 55% in Paramerina) and the claws with combs of teeth Xen claws, where Paramerina cingulata only has one claw with one inner tooth Par claw.
Diversity
European species: 2
Treated species: 0