(Johannsen, 1905)
Body
Medium-sized up to 10 mm long. Living larvae red with green. Claws on the posterior parapods are simpel. No lateral and ventral tubules (Wiederholm, 1983; Moller Pillot, 1984a).
Head
Unusually narrow, more than 2 x as long (0.45 mm) as wide (0,20 mm) with 2 pairs of eyes Pach longif eyes pict (Moller Pillot, 1984a)
Antenna
The antenna consists of 5 segments. The basal segment is longer than the flagellum.
Mentum
The mentum has 1 notched median tooth Parach frequ mentum, which might appear simpel when worn Parach Kampen mentum and 7 pairs of lateral teeth. The ventromental plates, radiating in a fan-like way, are 0.9 - 1.2 x as wide as the mentum.
Labrum
SI is divided into 3 - 5 lobes and labral lamellae are absent. The pecten epipharyngis with several rows of teeth. The premandible with 4 apical teeth.
Mandible
The mandible with one long apical tooth and 2 inner teeth. Pecten mandibularis present (Moller Pillot, 1984a).
Differential characteristics
The species with one median mental tooth can be distinguished by the flat mentum and 7 pairs of lateral teeth. Parach arc mentum. The species with 2 median teeth can be separated by the 7 pairs of lateral teeth, flat mentum Parach vitiosus mentum and 2-4 teeth on the premandible Parach vitiosus premandible where Harnischia has 6 teeth.
P. longiforceps can be separated from the other Parachironomus by the notched median mental tooth. Also the fan-like radiation of the ventromental striae and the lobed SI are distinctive.