(Zetterstedt, 1850)
Body
Medium sized larvae up to 8 mm long (Wiederholm, 1983). Living larvae are vivid green or blue-green (Moller Pillot, 1984b). The L4 setae of the abdomen are short and simpel. The anterior and posterior parapods and heavely sclerotized and the procerci are present (Wiederholm, 1983).
Head
The head length is 0.6 mm (Moller Pillot, 1984b).
Antenna
The antenna consists of five segments. The blade is shorter than the flagellum and the lauterborn organs are present.
Mentum
The dark mentum has a broad median tooth, subdivided in four parts and 6 pair of lateral teeth Acric lucens mentum. The beard is very large and visible at low magnification Acric lucens head. The ventromental plates are broad, but do not cover the mentum.
Labrum
The pecten epipharyngis consists of three scales, SI bifid and premandible with a single apical tooth (Wiederholm, 1983).
Mandible
The mandible with a distal tooth and three smaller teeth within. Seta interna is absent (Wiederholm, 1983; Moller Pillot, 1984b).
Differential characteristics
The combination of a single middle tooth of the mentum, the beard Acric lucens mentum and the bifid SI confirms only with Acricotopus, Halocladius and Paracladius. Acricotopus differs from Halocladius in the shape of the mentum and having 2 pairs of anal tubules instead of one in Halocladius. Acricotopus differs from Paracladius in having a dark mentum instead of a pale median tooth in Paracladius.