The newly described aquatic insects, belonging to the genus Hydropsyche, help close substantial knowledge gaps regarding the biodiversity of Azerbaijan, Iran, and Türkiye. Caddisflies (order Trichoptera) are vital components of freshwater ecosystems, and the Hydropsyche genus is among the most diverse and ecologically important, comprising more than 8% of all Trichoptera species recorded in the Western Palaearctic region The findings were recently published in the open-access peer-reviewed Biodiversity Data Journal.

Both new species were found in habitats characterized by stone, pebble, and fine sediments with sparse riparian vegetation. Hydropsyche fitesa was discovered in Iran, specifically near the Shalmash Waterfalls on the Chamyaman River, a tributary originating in the Zagros Mountains; the epithet fitesa honors the first author's wife, in recognition of her lifelong support of caddisfly research. Hydropsyche hindrajab was found across multiple river localities in Azerbaijan, Iran, and Türkiye, and was named in honor of Hind Rajab, a five-year-old girl whose life was lost amid the Israeli-Palestinian conflict.

Authored by Halil Ibrahimi (University of Prishtina, Kosovo) and Dora Hlebec (University of Zagreb, Croatia), the study highlights the challenges of identifying morphologically similar species. Because both new insects belong to the Hydropsyche guttata species cluster - a group whose members look strikingly alike - the team employed an integrative taxonomic approach.

By combining traditional morphological examination with advanced DNA analysis (specifically, sequencing of the mitochondrial cytochrome c oxidase subunit I, or COI gene), the researchers confirmed that H. hindrajab represents a distinct evolutionary lineage. H. fitesa was distinguished based on unique morphological differences in its physical structure compared to its closest relatives.

The discovery underscores how much of the region's aquatic life remains undocumented. The authors note that the type localities in West Azerbaijan Province, Iran, are known for harboring rare aquatic insects, and they believe the area likely holds additional undescribed species yet to be found. Currently, 23 Hydropsyche species are known in Iran, 67 in Türkiye, and 12 in Azerbaijan, but the potential for new discoveries remains high.

Original study:

Ibrahimi H, Hlebec D (2026) Two new species of the genus Hydropsyche Pictet, 1834 (Trichoptera, Hydropsychidae) from the Middle East and Caucasus ecoregions. Biodiversity Data Journal 14: e191076. https://doi.org/10.3897/BDJ.14.e191076

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