Van der Wulp, 1874
Body
Medium sized to large larvae up to 12 mm long. Living larvae are greenish or brownish. The L4 setae are simpel. The anterior and posterior parapods are separate and bear rows of claws. Procercus and two pairs of anal tubules present (Wiederholm, 1983; Moller Pillot, 1984b).
Head
Antenna
The antenna consists of five segments Orth (Eu) thien antenna (4 in O. consobrinus) Pogo cons antenna. The blade is shorter than the flagellum. Lauterborn organs are small to conspicuous.
Mentum
The mentum has one median tooth and 6 pairs of lateral teeth Orth (O) mentum 8 (7-9 in the subgenus Euorthocladius). The ventromental plates are weak. The beard is absent (present in O. consobrinus) (Wiederholm, 1983).
Labrum
The pecten epipharyngis consists of three scales, SI is bifid Orth frigidus labrum9 and the premandible has one or two apical teeth (Wiederholm, 1983; Moller Pillot, 1984b).
Mandible
The mandible has an apical tooth of normal length and 3 inner teeth Orth frigidus mandible. The seta interna has simpel to serrate branches or may be absent in the subgenera Eudactylocladius and Euorthocladius (Wiederholm, 1983).
Differential characteristics
Orthocladius can be separated from all other genera, except Paratrichocladius, by the bifid SI, mentum with 1 median tooth and 6-9 pairs of lateral teeth, 5 segmented antenna (4 in O. consobrinus) and simpel body seta (Except O. holsatus, which has a longer apical tooth on the mandible than the genus Cricotopus). Paratrichocladius however has a blueish thorax in freshly preserved larvae and a lobed ring beneath the ssd of the mandible. Both characters are absent in Orthocladius.
Diversity
European species: 34
Treated taxa:
Species-group Orthocladius gr. fuscimanus
Species-group Orthocladius gr. mixtus
Orthocladius consobrinus
Orthocladius frigidus
Orthocladius holsatus
Orthocladius luteipes
Orthocladius obumbratus
Orthocladius rivicola
Orthocladius rivulorum
Orthocladius rubicundus
Orthocladius thienemanni
Orthocladius wetterensis