Beetles (Insecta: Coleoptera) in Andanan Watershed Forest Reserve, Mindanao, Philippines

Beetles (Insecta, Coleoptera) fauna play a crucial role in the food web and serve as a valuable bioindicator of the ecosystem health. In the riparian forest zone of Andanan Watershed Forest Reserve, 52 species from 45 genera and 24 subfamilies were recorded. Scarab beetles (family Scarabaeidae) had the highest species richness, with eleven species, including the largest species, Chalcosoma atlas. Other phytophagous groups, such as longhorn beetles (Cerambycidae: 8 species) and weevils (Curculionidae: 7 species), were also documented. Additional families observed include Cantharidae, Carabidae, Chrysomelidae, Cicindelidae, Coccinellidae, Elateridae, Endomychidae, Lampyridae, Lucanidae, Lycidae, Meloidae, Passalidae, and Prionoceridae. Notably, the endemic tiger beetle Calomera mindanaoensis, found only in Mindanao, was recorded, along with the recently discovered species of scarab beetles – Engertia lii and Philacelota leucothea, reported in 2006 and 2019, respectively, and considered endemic to the Philippines. Additionally, the records of two cantharid beetles (Cordylocera and Paradiscodon), two elaterid beetles (Lanelater and Paracalais), and a blister beetle (Zonitoschema) may represent the first documentation of these groups in Mindanao.