DNA based association and description of the larval stage of Drusus melanchaetes McLachlan, 1876 (Trichoptera: Limnephilidae: Drusinae) with notes on ecology and zoogeography.

At three alpine locations in Switzerland adults of Drusus melanchaetes and unknown Drusinae larvae which could not be identified with existing keys were sampled. Based on DNA association with adults, we identified the unknown larvae as D. melanchaetes. To further support the association of specimens a phylogeny was estimated with the putative closest relatives of D. melanchaetes - D. monticola and D. nigrescens - and five other species of Drusus (D. chrysotus, destitutus, discolor, muelleri and romanicus). A highly supported monophyletic clade groups unknown larvae and D. melanchaetes specimens from the central Alps and Austria (Vorarlberg), confirming the association. Based on morphology, larvae of Drusus melanchaetes key out together with D. destitutus in existing keys. D. melanchaetes is separated from the latter species by the shape of the lateral head profile which is almost straight and shows a small step at the height of the antenna, whereas in D. destitutus the lateral head profile is evenly rounded. In addition, in frontal view, the shape of the lateral head outline is straight in D. melanchaetes and rounded in D. destititus. There are also differences in the shape of the pronotum and in the number of the posterodorsal setae at the eighth abdominal dorsum.