Temporal Dynamics and Species Turnover in Coleoptera Assemblages from the Goa University Campus, Goa, India

Beetles (Order: Coleoptera) are ecologically important insects involved in decomposition, nutrient cycling, pollination, biological control, and serve as indicators of terrestrial biodiversity. Despite their significance, beetle diversity in Goa remains poorly documented. This study documents beetle diversity and temporal dynamics on the Goa University campus, Taleigao plateau, a unique lateritic ecosystem. Systematic surveys were carried out using line transect method from roadside vegetation, leaf litter and associated microhabitats over a 12-week survey period. Species identification was based on morphological characters: body shape and size, antennal morphology, colouration and elytral patterns, pronotum, legs, and surface texture. Diagnostic family traits, including elongated rostrum (Curculionidae), long antennae (Cerambycidae), brightly coloured oval bodies (Chrysomelidae), and dome-shaped spotted bodies with clubbed antennae (Coccinellidae) were used. A total of 22 species from six families, all within the suborder Polyphaga, were recorded: Chrysomelidae (12 species), Coccinellidae (2), Curculionidae (2), Scarabaeidae (4), Tenebrionidae (1), and Cerambycidae (1). Eleven Coleopterans were detected from the first survey week, with no significant temporal trend in weekly richness (Kendall's τ = 0.00, p = 1.000), suggesting relatively stable species richness throughout the survey period (mean ± SD: 9.83 ± 1.40 species per week; range: 7–12). Species accumulation reached near-saturation by week 6, with only five new detections after week 3, suggesting that the survey adequately sampled the local beetle fauna. Chrysomelidae dominated across all weeks (82 cumulative records), with Nisotra gamella being the most temporally persistent species, detected in all 12 weeks. Despite relatively stable richness, week-to-week community turnover was moderate (mean Jaccard dissimilarity = 0.465), reflecting compositional variation. NMDS ordination (stress = 0.115) revealed no clear temporal trajectory, consistent with a well-established assemblage lacking directional phenological succession. These findings suggest that the surveyed beetle assemblage exhibited relatively stable species richness but moderate compositional turnover during the monsoon season.