Functional traits of ancestral caddisfly (Trichoptera) larvae and pupae.

Recent phylogenomic studies have concluded that the ancestor of order Trichoptera and suborder Integripalpia probably had a larva that was "free living," without a portable case or fixed retreat. Phylogenies inferred from those investigations regarding hypotheses for other probable functional traits of larvae and pupae of the Trichoptera ancestor and its immediate descendants were considered, especially with reference to the extant amphiesmenopteran sister lineage Lepidoptera. To test our hypotheses an Ancestral Character State Reconstruction by Parsimony Analysis was performed to explore functional traits for five habitat and behavioral traits. Like the larva of Micropterigidae, the basal lineage of Lepidoptera, the ancestral caddisfly larva was not only "free living" but also was a shredding herbivore of bryophytes. Like that larva, it may have been often submerged, perhaps as a semi-aquatic sprawler in madicolous or hygropetric habitats, but it could also have been a clinger in lotic-erosional habitats. Also, the characteristics of the pupal cocoon are not clear; it may have been closed and permeable like that of Micropterigidae, or it was closed and semipermeable like that of Hydroptilidae, or it was open in a long-dome shelter like that of the Annulipalpia ancestor.