Taxonomy offers precise species identification and delimitation and thus provides basic information for biological research, e.g. through assessment of species richness. The importance of molecular taxonomy, i.e., the identification and delimitation of taxa based on molecular markers, has increased in the past decade. Recently developed exploratory tools now allow estimating species-level diversity in multi-locus molecular datasets. Here we use molecular species delimitation tools that either quantify differences in intra- and interspecific variability of loci, or divergence times within and between species, or perform coalescent species tree inference to estimate species-level entities in molecular genetic datasets. We benchmark results from these methods against 14 morphologically readily differentiable species of a well-defined subgroup of the diverse Drusinae subfamily (Trichoptera, Limnephilidae). Using a 3798 bp (6 loci) molecular data set we aim to corroborate a geographically isolated new species by integrating comparative morphological studies and molecular taxonomy. Our results indicate that only multi-locus species delimitation provides taxonomically relevant information. The data further corroborate the new species Drusus zivici sp. nov. We provide differential diagnostic characters and describe the male, female and larva of this new species and discuss diversity patterns of Drusinae in the Balkans. We further discuss potential and significance of molecular species delimitation. Finally we argue that enhancing collaborative integrative taxonomy will accelerate assessment of global diversity and completion of reference libraries for applied fields, e.g., conservation and biomonitoring.

In a recent 3-gene phylogeny of the trichopteran subfamily Drusinae Banks 1916, molecular data clearly correlated with the morphology and feeding ecology of larvae. The largest of three main groups, the Drusinae grazer clade, exhibits an unusual larval feeding ecology for Limnephilidae, and is the most diverse group. In this paper we describe four previously unknown Drusinae larvae included in this clade: Drusus balcanicus Kumanski, 1973 (micro-endemic to Eastern Balkans), Drusus botosaneanui Kumanski, 1968 (Dinaric Western Balkans, Hellenic and Eastern Balkan, Asia Minor), Drusus serbicus Marinkovi?-Gospodneti?, 1971 (micro-endemic to Dinaric Western Balkans), and Drusus tenellus (Klap?lek, 1898) (Carpathians, Dinaric Eastern Balkans). Characteristically, the larvae of these species have toothless mandibles typical of the Drusinae grazer clade. Larvae and adults were unambiguously associated using a phylogenetic analysis based on two mitochondrial [mtCOI, mtLSU (=16S) rDNA] and two nuclear genes (nuWG, nuCAD). In addition, information on the morphology of the larvae is given and the diagnostic features necessary for identification are illustrated.

In this paper, we describe a new species, Potamophylax idliri sp. nov., from the Jastrebac Mountains in Serbia, which is morphologically most similar to Potamophylax coronavirus Ibrahimi, Bilalli & Vitecek 2021 (in Ibrahimi et al. 2021) and Potamophylax juliani Kumanski 1999 (in Kumanski & Malicky 1999). The males of the new species differ from all known species of the Potamophylax winneguthi Species Group by morphological characters of the male genitalia. The genetic distinctiveness calculated based on sequencing of the barcode region of the cytochrome c oxidase subunit I gene (COI) between Potamophylax idliri sp. nov. and other species of the Potamophylax winneguthi Species Group is on par with those of other morphologically recognized species in the group and especially the other four species of the P. winneguthi Species Cluster. Potamophylax winneguthi Species Cluster is erected for the following species: P. idliri sp. nov., P. winneguthi, P. haidukorum Malicky 1999 (in Kumanski & Malicky 1999), P. juliani, and P. coronavirus, characterized primarily by the bilobed apical margins of inferior appendages with pointed corners, in lateral and caudal views. The new species was found at two localities in the Jastrebac Mountains, at 988 and 891 m above sea level. Considering the knowledge about distribution and ecology of the other species of this group, we posit that P. idliri sp. nov. is a microendemic of the Jastrebac Mountains in Serbia.