Study area and sampling
Four field expeditions were conducted during 2019 and 2020 (February-March/ October-November and June-July/ November-December, respectively) during dry and rainy seasons. Specimens were sampled using six UV-light traps (Ranasinghe et al. 2020) in 11 localities covering different forest types and altitudinal zones of Sri Lanka (Figure S1). Sites are in evergreen wet lowland forests (below 500m: L1, L8, L9; or above 500m: L12, L13, L14), evergreen dry lowland forest (L3), sub-montane forests (L2, L4), or montane forests (L5, L11) (Figure S1, Table S1). Traps were placed in each locality at different sampling sites (i.e., macrohabitats) at approximately 2 m above ground (Table S1). They were positioned at the same location for 2–3 consecutive days and operated from 6 pm to 11 pm. All traps (traps A-F) were separated by at least 100–500m, to not influence each other. Beetles were trapped in a sampling container with preservation liquid (96% ethanol) (for trap design, see Ranasinghe et al. 2020; 2022). Specimens were preserved in 96% ethanol. In total, we performed 10-12 trapping events per expedition/site, resulting in 60-72 trapping events in each location.
Phytophagous chafers (Coleoptera: Scarabaeidae) in Sri Lanka include Dynastinae, Melolonthinae, and Rutelinae. Specimens were identified to morphospecies based on external and genital morphology, some being subsequently examined by a specialist. Specimens are deposited in the Zoological Research Museum A. Koenig, Bonn (ZFMK) and in the National Institute of Fundamental Studies, Kandy, Sri Lanka (NIFS).