New species are described in the genera Wormaldia (Trichoptera, Philopotamidae) and Drusus (Trichoptera, Limnephilidae, Drusinae). Additionally, the larva of the new species Drususcrenophylax sp. n. is described, and a key provided to larval Drusus species of the bosnicus-group, in which the new species belongs. Observations on the threats to regional freshwater biodiversity and caddisfly endemism are discussed. The new species Wormaldiasarda sp. n. is an endemic of the Tyrrhenian island of Sardinia and differs most conspicuously from its congeners in the shape of segment X, which is trilobate in lateral view. The new species Drususcrenophylax sp. n. is a micro-endemic of the Western Balkans, and increases the endemism rate of Balkan Drusinae to 79% of 39 species. Compared to other Western Balkan Drusus, males of the new species are morphologically most similar to Drususdiscophorus Radovanovic and Drususvernonensis Malicky, but differ in the shape of superior and intermediate appendages. The females of Drususcrenophylax sp. n. are most similar to those of Drususvernonensis, but differ distinctly in the outline of segment X. Larvae of Drususcrenophylax sp. n. exhibit toothless mandibles, indicating a scraping grazing-feeding ecology.