A Cretaceous Caddisfly Larva Encased in Amber and Its Evolutionary Implications (Insecta: Trichoptera)

Fossil record of caddisflies with both larvae and their cases is exceedingly rare. This study focuses on a 99-million-year-old Burmese amber specimen containing a caddisfly larva and its case, alongside other organisms. The specimen was examined using microscopy, photography, widefield fluorescence imaging, and micro-CT scanning to analyze its structure and identify associated organisms. The amber contains a diverse assemblage, including a caddisfly larva, a mayfly nymph, water mites, a terrestrial bug nymph, and a beetle larva. Detailed morphological descriptions reveal adaptations of the caddisfly larva for aquatic life and case construction, shedding light on its taxonomic classification and behavioral adaptations. The proximity of the caddisfly larva to a layer of debris suggests it inhabited a shallow, slow-flowing stream environment. Morphological features indicate its classification within the suborder Integripalpia, with characteristics bridging primitive forms and more derived lineages. Behavioral traits such as case abandonment highlight adaptive strategies for survival and dispersal in response to environmental stressors. This study contributes to understanding ancient aquatic ecosystems and the evolutionary history of caddisflies. It reveals insights into symbiotic relationships, behavioral adaptations, and ecological dynamics, emphasizing the significance of fossilized remains in elucidating past life forms and aquatic environments.