Abstract
A fossil Cenozoic late instar strepsipteran larva is described and evaluated phylogenetically. The single specimen is embedded in Eocene Baltic amber. The short antennal buds, mandibles not intercrossing in the midline, unsegmented tarsi, and the elongated slender claws clearly indicate that it is not an adult female but a late larval instar. The low number of ommatidia of the compound eyes strongly suggests that it is an immature female. Besides this, wing buds are missing in contrast to male puparia of Mengenillidae. Phylogenetic analyses of characters of female late instar larvae indicate that the species belongs to the stem group of Strepsiptera. The presence of distinctly developed mouthparts and legs show that the larva does not belong to Stylopidia. The presence of a distinct clypeolabral suture, a large labrum, and claws which are elongated but not filiform exclude it from crown group Strepsi-ptera. It is likely that it is a female larva of the extinct genus †Mengea, which is only known from Eocene Baltic amber. Small size excludes an assignment to †Protoxenos, which is known from the same period. Characters of the fossil entered in a comprehensive matrix assuming that the larva belongs to †Mengea confirm a sistergroup relationship between the fossil described here and extant Strepsiptera.
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