Holoptic eyes of a male syrphid (Eristalinus taeniops)
Holoptic male of Tabanus biguttatus
Holoptic refers to the way the eyes of various species of insects meet along the dorsal mid-dorsal line of the head, in many species nearly covering the exterior of the head. Holoptic eyes are typical of several Dipteran males, in particular some Syrphidae, Tabanidae, Pipunculidae, and Acroceridae. Some other insect orders that include species with holoptic males and some in which the females are holoptic as well, include the Coleoptera, Anisoptera and Archaeognatha.
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