The first fossil hilarimorphid fly (Diptera: Brachycera)

• The first fossil hilarimorphid is described from the Lower Cretaceous Lebanese amber.
• Cretahilarimorpha differs from the modern Hilarimorpha in wing venation, antenna and mouthparts.
• The very elongate mouthparts are adapted for nectar feeding in deep flowers, rare in the Lower Cretaceous.

Although recent molecular phylogenetic analyses suggest a great antiquity, going into the Jurassic, for the small modern fly family Hilarimorphidae, no fossil was attributed to this group. The first fossil hilarimorphid Cretahilarimorpha lebanensis gen. et sp. nov., is described, based on a specimen from the Lower Cretaceous Lebanese amber. Its external morphology is analysed and compared with that of Hilarimorpha, unique modern hilarimorphid genus. The differences concern the wing venation, antenna and especially mouthparts. Cretahilarimorpha has very elongate mouthparts, adapted for nectar feeding or (less probably) for predation on other insects. Several other Lower Cretaceous lineages have developed similar elongate mouthparts, viz. nemestrinid and xylomyiid flies, and the Mecoptera: Aneuretopsychina, probably adapted to still unknown deep nectar-producing flowers. A checklist of species belonging to the Hilamorphidae is given.

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