Eudioctria tibialis

(Banks, 1917)

Eudioctria tibialis is a of robber fly in the Asilidae, Stenopogoninae. It is among the smallest North American robber flies, measuring 6–8 mm in length. The species is one of four Eudioctria species occurring in eastern North America, with the being primarily western in distribution. It was first described by Banks in 1917.

Pronunciation

How to pronounce Eudioctria tibialis: //ˌjuːdiˈɒktriə tɪˈbaɪəlɪs//

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Identification

Eudioctria tibialis can be distinguished from other eastern Eudioctria (E. albius, E. brevis, E. propinqua) by specific facial gibbosity structure and degree of pollinosity on body parts, requiring close examination. The Eudioctria superficially resembles Cerotainia ( Laphriinae) but lacks the extra-long characteristic of that genus. Behaviorally, Eudioctria prefers perching on flat leaves at the top of small shrubs, whereas Cerotainia tends to perch on twig-ends.

Appearance

A very small robber fly measuring 6–8 mm in length. identification requires examination of facial gibbosities (raised areas on the ) and assessment of pollinosity (dusty or powdery covering) on various body parts.

Distribution

Eastern United States. One of four Eudioctria (along with E. albius, E. brevis, and E. propinqua) that occur in eastern states, while the is primarily distributed in the western United States.

Behavior

Has been observed perching on flat leaves at the top of small shrubs. This perching distinguishes it from the similar-looking Cerotainia, which prefers twig-ends.

Ecological Role

Predatory robber fly, likely feeding on small insects as is typical for the Asilidae.

Similar Taxa

  • CerotainiaSuperficially similar in appearance but distinguished by extra-long and different perching (twig-ends vs. flat leaves)
  • Eudioctria albiusAnother eastern Eudioctria requiring examination of facial gibbosities and pollinosity for separation
  • Eudioctria brevisAnother eastern Eudioctria requiring examination of facial gibbosities and pollinosity for separation
  • Eudioctria propinquaAnother eastern Eudioctria requiring examination of facial gibbosities and pollinosity for separation

More Details

Taxonomic note

The Eudioctria contains approximately 14 , with most distributed in the western United States. The four eastern species (E. albius, E. brevis, E. propinqua, E. tibialis) represent a notable disjunction in the genus distribution.

Identification difficulty

-level identification within Eudioctria is challenging and typically requires examination of minute morphological features including facial gibbosities and pollinosity patterns, best determined by .

Sources and further reading