Dragonfly Guide

Onychogomphus

Onychogomphus is a genus of dragonflies in the family Gomphidae. They are commonly known as Pincertails.

Identification

These dragonflies are best known for the male's large appendages. The upper and lower appendages are both distinctly longer than S10 and are curved strongly inwards, like pincers. All species, except O. costae, have a yellow abdomen ringed with black markings, and a yellow thorax with black stripes O. costae is more brown and less distinctly marked. The hindwing has a small anal loop consisting of 1-3 cells. Therefore there is not a straight perpendicular vein running directly to the wing's hind margin from the last thick lengthwise vein in the wing base.

Separation from other genera

The males can hardly be misidentified because of their conspicuous appendages, but females are less obvious. They may be mistaken for Gomphus, Ophiogomphus or Paragomphus. Only Ophiogomphus also has an anal loop, but in this genus the thorax is largely green and the female has two crests on top of the occiput. Paragomphus species are smaller. The male has broad flaps on S8-9 and the female has a row of small black denticles on the rear of the occiput. Gomphus is marked differently, the abdomen generally blacker and is lenghtwise striped, rather than ringed.

Distribution

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Distribution map. Data from gbif.org

Sources

  • Wikipedia

  • Field guide to the dragonflies of Britain and Europe, Klaas-Douwe B Dijkstra.