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 16 / 22 areas with high suitability and little or no research effort, so efforts should be made to describe new species. In addition to unknown species, some valid species exhibit weak circumscription or inconsistencies [see 32,40]. In H. (Cochliopsyche), there is little difference in genital characteristics (the primary features for species distinction), thus, detailed description of genitalia, standardization, and better circumscription of species are relevant to avoid misidentifications. The Wallacean shortfall is evident in the limited data available on species distribution [8]. Distributional information is often restricted to type localities or adjacent areas (Fig 2A and B), a trend that is also reflected in our results. This high- lights the urgent need to increase faunistic surveys in unexplored areas with high environmental suitability (Fig 1C,F, and H) and to analyze the material already housed in collections. Key regions with significant research effort and species rich- ness include: (i) Antillean subregion in Hispaniola, Puerto Rico – Virgin Islands, Windward & Leeward Islands, and Cuba Cayman Islands (eastern and western extremes) Freshwater Ecoregions; (ii) Mesoamerican dominion in San Juan, Estero Real – Tempisque, Chiriqui, Isthmus Caribbean, Chagres, South America Caribbean Drainages – Trinidad and south portion of Magdalena – Sinu Freshwater Ecoregions, (iii) Brazilian dominion only near Manaus city, Amazonas, and (iv)

Parana dominion in Paraíba do Sul, Northeastern Mata Atlântica, São Francisco, and Fluminense Freshwater Ecoregions (Fig 1G and H). In contrast, areas such as (i) Boreal and South Brazilian dominions; and (ii) areas east of Caatinga Cerrado and Chacoan provinces where they are bordered by the Atlantic Forest and Paraná provinces remain largely underex- plored despite showing high environmental suitability, indicating strong potential for species distribution. Prioritizing these regions for future faunistic surveys targeting Helicopsychidae is essential to fill existing knowledge shortfalls. These efforts will likely lead to the discovery of previously undescribed taxa and a more comprehensive understanding of species distributions [8]. In doing so, they will help address both Linnean and Wallacean shortfalls, while also con- tributing to resolving Haeckelian and Hutchinsonian shortfalls if semaphoronts and abiotic conditions are thoroughly documented. Given the Wallacean and Linnean shortfalls in caddisfly research, our understanding of species diversity and taxo- nomic groups remains incomplete, particularly within Trichoptera [36], where a male-biased focus persists—a gap that aligns with the Haeckelian shortfall [more details, 9]. Biodiversity biases often stem from research concentrated in easily accessible areas with prior survey efforts [3]; however, in this case, the sexual bias is significantly amplified. Therefore, acknowledge that all subsequent discussions are inherently influenced by these knowledge shortfall, reflecting the broader

discrepancies in our understanding of New World Helicopsychidae, a scenario that is similarly prevalent across most insect orders. Fig 4. Boxplot of biogeoclimatic variables of New World Helicopsyche species. A. Annual mean precipitation range of Helicopsyche (Cochliopsy- che) species; B. Annual mean precipitation range of Helicopsyche (Feropsyche) species; C. Annual mean temperature range of Helicopsyche (Cochlio- psyche) species; D. Annual mean temperature range of Helicopsyche (Feropsyche) species. https://doi.org/10.1371/journal.pone.0327580.g004 Table 3. Environmental variables used for species modelling, using 80% correlation cut-off. Variables group Code Variables Bioclimatic Bio_7 Temperature Annual Range (Annual Precipitation- Min Temperature of Coldest Month) Bio_2 Annual Precipitation Elevation Elev Elevation Precipitation Prec_01 and 08 Precipitation (mm) Solar radiation Srad_03, 04 and 07 Solar radiation (kj m-2 day-1) Wind speed Wind_01 Wind speed (m s-1) https://doi.org/10.1371/journal.pone.0327580.t003