A new caddisfly: Drusus sharrensis

Caddisflies belong to the order Trichoptera, and are closely related to butterflies and moth. As larvae they live in most freshwater habitats. For their own protection they live in cases, that they make themselves. They spin out silk, and either live in silk nets or use the silk to stick together bits of whatever is lying on the stream bottom, e.g. pebbles or debris. 

Most of the caddisflies are herbivorous, that is, they eat decaying plant tissue and algae. Their favorite algae are diatoms, which they scrape off of rocks. Some of them, though, are predacious: they eat other animals.

The new caddisfly species was found during a field trip in the Sharr National Park in Kosovo, hence the species name. The aquatic insect belongs to the highly diverse genus Drusus, which is under threat of extinction because of the ongoing pollution activities and mismanagement of freshwater ecosystems.

For the experts: In this paper we describe Drusus sharrensis sp. n., from the Sharr Mountains in Kosovo. Males of the new species are morphologically most similar to Drusus krusniki Malicky, 1981, D. kerek Oláh, 2011 and D. juliae Oláh, 2011 but differ mainly in exhibiting (1) a differently shaped spinose area on tergite VIII; (2) intermediate appendages anteriorly curved in lateral view with broad tips in dorsal view; (3) inferior appendages with a distinct dorsal protrusion in the proximal half. Females of the new species are morphologically most similar to D. krusniki, D. kerek, D. juliae, and D. plicatus Radovanovic, 1942 but mainly differ in (1) segment X that is longer than the supragenital plate with distinctly pointed tips; (2) supragenital plate quadrangular with a distinct round dorsal protrusion; (3) a vulvar scale with a small median lobe. Results of phylogenetic species delimitation support monophyly of Drusus sharrensis sp. n. and recover it as sister to a clade comprising (D. pelasgus Oláh, 2010 + D. juliae + D. arbanios Oláh, 2010 + D. plicatus + (D. dacothracus Oláh, 2010 + D. illyricus Oláh, 2010)). The new species is a micro-endemic of the Sharr Mountains, a main biodiversity hotspot in the Balkan Peninsula. Main threats to the aquatic ecosystems of this part of the Balkan Peninsula are discussed.