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 18 / 22 Bolivia (Chaco domain), and the coastal region of northwest and east South America. Much of continental Central Amer- ica, the Antilles, and the northwest of South America have been well sampled (Fig 1D). However, areas of the Chaco domain, the northern portion and Central Corridor of Atlantic Forest, and high-altitude areas of the Cerrado and Caatinga domains remain poorly sampled (Fig 1E). These areas should be prioritized for research efforts, in agreement with the Brazilian caddisfly studies of Santos et al. [24], which indicated the to prioritize research efforts in the Northeastern and Central-Western regions of Brazil. The Patagonian subregion is one of the least researched in the NT, with both groups exhibiting low suitability for this region. However, 11 species of H. (Feropsyche) are found in areas with minimum temperatures below 0°C (e.g., H. (Fer- opsyche) borealis, −17°C; H. (Feropsyche) minuscula, −12°C) (Fig 1D). The data available do not permit us to determine whether the low suitability is (i) due to the absence of favorable environmental conditions, or (ii) to the scarcity of data, which resulted in the model’s limitation for this area. In general, there is a considerable range of distribution records for the Helicopsyche in the NW. The species are distributed across a wide environmental gradient, with H. (Feropsyche) being particularly notable for their ability to occur in various freshwater environments across the New World. This includes a wide range of altitudes,

temperatures, and precipitation levels, with a preference for low-order environments (Figs 1,3, and 4). In contrast, H. (Cochliopsyche) species typically occur in lowlands, environments with higher average temperatures, and a preference for large rivers, reflecting a restriction in their occurrence to large river basins (Figs 1,3, and 4). Thus, the results indicate that the two lineages have specialized in different niches: H. (Feropsyche) specialized in smaller (low-order) environments, while the H. (Cochliopsyche) specialized in larger (high-order) environments. Similar patterns are also observed in other Trichoptera lineages, including Hydrobiosidae (Amphichorema and Atopsyche), and Glossosomatidae (Culoptila and Cariboptila) [33]. The results of this study highlight critical conservation implications for Helicopsychidae species in the New World. The identification of environmental gradients and the discovery of species with restricted distribution in high-suitability and low research effort areas emphasize the need for targeted conservation efforts. Areas with high species richness and environ- mental suitability, such as parts of Central and South America, should be prioritized for further research and protection. The underexplored regions, especially tropical rainforests and the dry diagonal zones (Caatinga, Cerrado, and Chaco), represent significant gaps in knowledge and potential hotspots for biodiversity. Increasing faunistic surveys in these regions will not

only enhance species descriptions but also help mitigate the risk of extinction for species with narrow distribution ranges, which are more susceptible to threats such as climate change and habitat loss. Moreover, the conservation of riparian habitats, particularly in large river basins, is critical to maintaining the integrity of ecosystems supporting these specialized species. By addressing both Linnean, Wallacean, Haeckelian, and Hutchinsonian and other shortfalls, future research can refine conservation strategies and promote the preservation of these important freshwater ecosystems. Conclusion The results highlight recent progress in the taxonomy and distributional cataloguing of New World Helicopsychidae, partic- ularly within underexplored regions of the Neotropics. Despite a substantial increase in described species, significant gaps in biodiversity knowledge remain. Current estimates suggest that up to 75% of Helicopsyche species in the region are still undescribed, emphasizing the urgent need for continued research efforts—ideally incorporating all semaphoronts—to fully document and understand the diversity of NW Helicopsychidae The distribution of Helicopsyche species reveals complex patterns influenced by environmental factors such as ele- vation, temperature, and precipitation. Species of H. (Cochliopsyche) are typically associated with larger river systems in warmer climates and extensive river basins, whereas H. (Feropsyche) species show broader ecological tolerance,

occurring across diverse freshwater habitats throughout the Americas, particularly in low-order streams. These contrasting patterns reflect distinct ecological specializations between the two subgenera.