A tale of divergence: The larval trunk of Sabatinca chalcophanes (Lepidoptera, Micropterigidae)

The evolutionary path that led to the “typical caterpillar” of the Neolepidoptera, the larval stage of more than 99 % of the extant species of the insect order Lepidoptera, involves seven families representing more basal lineages of the order. The family Micropterigidae represents one of the most basal lineages, and the soil dwelling biology of their larvae is considered ancestral to the larval biology of the entire order. Larval morphology of the micropterigids, however, appears to be very different from what is considered as the larval groundplan. Specializations to the soil dwelling lifestyle such as, interior cuticular chambers, slug like locomotion and an integumental mucous pellicle are without doubt autapomorphic to the micropterigids, but are at the same time adaptations to an ancestral biology. Detailed morphological study of the larval trunk of micropterigids, its comparison to the groundplan of the lepidoteran larvae, and to the “typical caterpillar” of the Neolepidoptera, may shed light on the evolution of lepidopteran larvae and the evolutionary succession from a soil dwelling mode of life in early lepidpterans to an angiosperm dependant mega-diverse order.