Honduran Cloud Forest Ant Survey Reveals Hidden Biodiversity

Tropical montane cloud forests are among the most biologically complex and geographically isolated ecosystems on Earth, yet they remain significantly understudied, particularly regarding their insect fauna. In a recent study published in Neotropical Biology and Conservation, researchers presented the first comprehensive ant species checklist for Cusuco National Park in northwestern Honduras. This work marks a significant milestone in regional myrmecology, as it is the first ant checklist for Honduras in over a century. The study combines data from multiple sampling projects to provide a baseline understanding of the ant community in this threatened ecosystem, highlighting the park’s role as a refuge for geographically isolated and endemic species.

Cusuco National Park, situated within the Merendon mountain range, is designated as one of the 137 most irreplaceable protected areas in the world. Despite its high conservation status, the park faces severe threats from deforestation and land conversion for subsistence agriculture. The study focused on an elevational range primarily between 1170 and 2030 meters above sea level, where the forest transitions from broadleaf evergreen trees to upper montane rainforest characterized by dense mosses, ferns, and bromeliads. This vertical gradient creates distinct microhabitats that support a rich diversity of ant species, many of which are specialized to specific elevational zones and are vulnerable to climate change and habitat loss.

The research team pooled data from two distinct projects: the Leaf Litter Arthropods of MesoAmerica (LLAMA) project and the Biodiversity Inventory for Conservation (BINCO) MyrmEcoDex workgroup. LLAMA, funded by the U.S. National Science Foundation, conducted standardized transect-based sampling in 2010, focusing on leaf litter-dwelling arthropods. In contrast, the MyrmEcoDex group participated in volunteer-funded expeditions from 2018 to 2019, employing a broader range of techniques including pitfall trapping and hand collection across a wider elevational spectrum. By integrating these datasets, the researchers were able to capture a more complete picture of the ant fauna, revealing that different sampling methods target different subsets of the community.

The study reported a total of 162 ant species belonging to nine subfamilies and 60 genera. The subfamily Myrmicinae was the most diverse, accounting for 54% of the recorded species, followed by Ponerinae and Dorylinae. Among the notable findings, five species were recorded for the first time in Honduras, including Pheidole natalie and Pseudomyrmex pallens. Additionally, the researchers documented the first collection of male individuals of Pheidole balatro, a species previously known only from workers. These males were found in a nest residing inside a bromeliad plant at 1613 meters elevation, providing valuable morphological data for future taxonomic comparisons.

Biogeographical analysis revealed that seven ant species in the park are regionally restricted to Honduras, with four of these being endemic to Cusuco National Park itself. These include Octostruma leptoceps, Stenamma cusuco, Stenamma atribellum, and Temnothorax altinodus. The presence of such restricted species underscores the park’s importance as a conservation priority. Conversely, the study identified two exotic species, Monomorium pharaonis and Solenopsis invicta, both of which are globally invasive. However, these were found primarily in the buffer zone or at the edges of the core zone, suggesting that the interior of the park remains largely unaffected by these invasive ants, at least for now.

Species accumulation curves and sample coverage analyses indicated that the current inventory likely underestimates the true ant diversity in the park. The asymptotic estimate suggests that the actual species richness could be as high as 257 species, with a 95% confidence interval ranging from 204 to 365. Leaf litter extraction proved to be the most efficient method for capturing species richness, accounting for 56% of the total species recorded, while hand collection and pitfall trapping also contributed significantly. The high community sample coverage for leaf litter extraction and baiting suggests that these methods are effectively capturing the common species, whereas Malaise trapping and vegetation beating still have the potential to reveal many more species, particularly those in the arboreal canopy.

The study also highlights significant knowledge gaps in the sampling effort. While the middle elevations were sampled most intensely, the higher mountain peaks and lower buffer zones remain undersampled. The researchers recommend expanding methodological approaches to include more canopy and subterranean sampling, as well as increasing the number of samples at higher altitudes where specialist species are likely to reside. Standardized sampling frameworks across the full elevational gradient would allow for a better understanding of species ecology and the impact of anthropogenic habitat changes on ant communities.

In addition to the species checklist, the authors provided a dichotomous identification key for all ant genera in Honduras. This tool is designed to aid future taxonomic efforts and make the Honduran ant fauna more accessible to researchers. The key was constructed by combining multiple existing works and identification resources, ensuring that it reflects the current state of taxonomic knowledge. By providing this resource, the study aims to stimulate further research in Honduras, a country that has been severely impacted by deforestation within protected areas.

The findings from this study demonstrate that Cusuco National Park harbors a surprisingly rich diversity of ant species, despite its relatively small area. This richness is consistent with patterns observed in other taxa within the park, reinforcing its status as a biodiversity hotspot. The information provided serves as a crucial baseline for future conservation efforts and research in Honduran cloud forests. As these ecosystems face increasing pressure from climate change and human activity, understanding the baseline biodiversity is essential for developing effective management strategies and protecting the unique species that depend on these habitats.

Ultimately, this work underscores the urgent need for continued field surveys in poorly explored yet highly threatened ecosystems. The discovery of new species and the documentation of endemic taxa highlight the potential for further biological discoveries in the region. By establishing a robust baseline for ant diversity in Cusuco National Park, the researchers have laid the groundwork for long-term monitoring and conservation planning. The study serves as a model for how integrating data from multiple projects and employing diverse sampling techniques can reveal the hidden complexity of tropical montane ecosystems, offering valuable insights for global biodiversity conservation efforts.

Subject of Research: Ants in the clouds: A preliminary checklist of the ant (Hymenoptera, Formicidae) fauna of a Honduran cloud forest ecosystem, featuring a key to country genera

Article Title: Ants in the clouds: A preliminary checklist of the ant ( Hymenoptera , Formicidae ) fauna of a Honduran cloud forest ecosystem, featuring a key to country genera

Article References: De Wint, F. C., Oorts, D., Branstetter, M. G., De Graaf, D., Dekoninck, W., Jocque, M., Martin, T. E., Sudworth, J., Van Osselaer, R., & Hamer, M. T. (2024). Ants in the clouds: A preliminary checklist of the ant (Hymenoptera, Formicidae) fauna of a Honduran cloud forest ecosystem, featuring a key to country genera. Neotropical Biology and Conservation, 19(2), 157-185. https://doi.org/10.3897/neotropical.19.e119775

Image Credits: AI Generated

DOI: 10.3897/neotropical.19.e119775

Keywords: Ants, clouds, preliminary, checklist, Hymenoptera, Formicidae, fauna, Honduran, cloud, forest, ecosystem, featuring