Addressing biodiversity knowledge shortfalls in New World Helicopsychidae (Insecta, Trichoptera): Potential distribution, environmental gradients, and identification of conservation and research priority areas

PLOS One | https://doi.org/10.1371/journal.pone.0327580 July 28, 2025 12 / 22 Of these, seven species are known exclusively from their larval cases: H. (Feropsyche) braziliensis (Swainson, 1840), H. (Feropsyche) colombiensis von Siebold, 1956, H. (Feropsyche) helicoidella (Vallot, 1855), H. (Feropsyche) minima von Siebold, 1956, H. (Feropsyche) scalaris Hagen, 1864, H. (Feropsyche) thelidomus Hagen, 1864, and H. (Feropsyche) umbonata Hagen, 1864 (Table 1). Regarding environmental gradients, Helicopsyche species occur along an elevation gradient from 0 to 5042 m above sea level (a.s.l.). With H. (Cochliopsyche) species range from 3 to 2457 m, with 80% found below 600 m (Fig 3A). In contrast, H. (Feropsyche) species range from 0 to 5042 m, with 45% of records above 600 m (Fig 3B), showing significant differences between subgenera distributions (F(1)=35.19, p-value = 0.001). Helicopsyche species are found across the 1st to 10th Strahler stream orders. The H. (Cochliopsyche) species has nearly half of its records above 4th order (45%), with a range from 1st to 10th order (Fig 3C). Conversely, H. (Feropsyche) species has less than 20% of its records above 4th order, with a range from 1st to 8th order (Fig 3D), indicating significant differences (F(1)=45.93, p-value = 0.001). The spe- cies occur in areas with annual precipitation ranging from 349 to 4427 mm³/year. The H. (Feropsyche) species has 47% of its records in areas with less than 1000 mm³/year (range 349–4427 mm³/year) (Fig 4A), while H. (Cochliopsyche) species

has 74% of its records in areas above 1000 mm³/year (range 959–3798 mm³/year) (Fig 4B), with significant differences (F(1)=58.52, p-value = 0.001). Temperature gradients range from −17°C to 40°C. The H. (Feropsyche) species is the only subgenus found in areas with negative temperatures, with a range from −17°C to 40°C (Fig 4C). In contrast, H. (Cochlio- psyche) species are found between 5°C and 35°C (Fig 4D), with significant differences (F(1)=55.10, p-value = 0.001). Distribution patterns of New World The northernmost species of H. (Feropsyche) is H. (Feropsyche) borealis, recorded in Canada at approximately 47°N, while the southernmost is H. (Feropsyche) caligata, found in Chile at around 39°S. In H. (Cochliopsyche), the northern- most species is H. (Cochliopsyche) vazquezae from Mexico (17°N), and the southernmost is H. (Cochliopsyche) opal- escens from Uruguay (32°S). The highest species richness in both subgenera is concentrated between latitudes 0° and 24°S (Fig 1). In the New World, biodiversity hotspots H. (Feropsyche) are concentrated in three main regions: (i) northwestern Colombia extending through Costa Rica, Nicaragua, and Panama, with 231 records representing 25 species; (ii) the Greater Antilles, with 165 records of 22 species; and (iii) eastern Brazil, with 93 records of 13 species (Fig 2A). For H. (Cochliopsyche), three prominent hotspots include: (i) northern Peru, much of Colombia, and Ecuador, with some exten- sion into the Amazon basin; (ii) the Central Amazon in Brazil; and (iii) eastern Brazil, encompassing the Central Atlantic

Forest Ecological Corridor and adjacent areas, and high-altitude areas of the Caatinga domain (Fig 2B). Species of Helicopsyche occur across 90 freshwater ecoregions [sensu 66]. The Northeastern Mata Atlântica Fresh- water Ecoregion harbors the highest species richness (23 spp.), followed by the South America Caribbean Freshwater Ecoregion (15 spp.), and both the Amazonas Lowlands and Paraíba do Sul Freshwater Ecoregions (14 species each). Helicopsyche (Cochliopsyche) is predominantly recorded from the Amazonas Lowlands (10 spp.) and Northeastern Mata Atlântica (8 spp.) Freshwater Ecoregions, whereas H. (Feropsyche) is more frequent in the South America Caribbean (15 spp.), San Juan (Nicaragua and Costa Rica), and Paraíba do Sul (12 species each) Freshwater Ecoregions (see S2 Table for details). Fig 2. Distribution range and species new species history of New World Helicopsychidae. A. Number of records and distribution range of Heli- copsyche (Cochliopsyche) species. B. Number of records and distribution range of Helicopsyche (Feropsyche) species. C. History of new and number of Helicopsyche (Cochliopsyche) species over time. D. History of new and number of Helicopsyche (Feropsyche) species over time. E. Heatmap of distribution for Helicopsyche (Cochliopsyche). F. Heatmap of distribution for Helicopsyche (Feropsyche). Map created in QGIS v3.40.7. Background: ESRI land cover (https://livingatlas.arcgis.com/landcover/) accessed via the QuickMapServices plugin, country boundaries: geoBoundaries (https://www. geoboundaries.org/), both under CC BY 4.0 license.

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