DragonflyPix

Tau Emerald (Hemicordulia tau)

The Tau Emerald (Hemicordulia tau) is a dragonfly species of the family Corduliidae, which contains 12 species in Australia.

The identification key to the family Corduliidae consists of 11 couplets, 4 of which are pertinent to Hemicordulia tau. Click on the numbers on the right to display the corresponding couplets. Or click on the ALLin1 button to see all the relevant couplets together in a single, scrollable window.

#FamilySpeciesCouplet No.
 CorduliidaeTau Emerald
(Hemicordulia tau)
  • Corduliidae: Key couplet 1 of 11

  • couplet drawing
  • ● Hypertriangles generally free
  • b ↑
  • Corduliidae: Key couplet 2 of 11

  • couplet drawingcouplet drawing
    couplet drawing
  • ● Three crossveins between sectors of arculus basal to fork of Rs in hindwing
    ● Bridge crossvein at subnodus
    ● Ovipositor short, less than half length of tergum 9

    ⇒ genus: Hemicordulia and Procordulia
  • b ↑
  • Corduliidae: Key couplet 3 of 11

  • couplet drawing
  • ● Top of frons yellow with dark T-mark, or black with pair of yellow spots
  • b ↑
  • Corduliidae: Key couplet 8 of 11

  • couplet drawing
  • ● Abdominal tergum 7 extensively black above, yellowish at sides

    ⇒ species: Tau Emerald (Hemicordulia tau)
  • a ↑
1  
  • Corduliidae: Key couplet 1 of 11

  • couplet drawing
  • ● Hypertriangles of both wings crossed

    ⇒ species: Metallic Tigerhawk (Pentathemis membranulata)
a ↑
b ↓
  • couplet drawing
  • ● Hypertriangles generally free

2  
  • Corduliidae: Key couplet 2 of 11

  • couplet drawingcouplet drawing
    couplet drawing
  • ● Two crossveins between sectors of arculus basal to fork of Rs in hindwing
    ● Bridge crossvein between subnodus and oblique vein
    ● Ovipositor long, spoon-like, extending to or beyond end of abdomen

    ⇒ species: Offshore Emerald (Metaphya tillyardi)
a ↑
b ↓
  • couplet drawingcouplet drawing
    couplet drawing
  • ● Three crossveins between sectors of arculus basal to fork of Rs in hindwing
    ● Bridge crossvein at subnodus
    ● Ovipositor short, less than half length of tergum 9

    ⇒ genus: Hemicordulia and Procordulia

3  
  • Corduliidae: Key couplet 3 of 11

  • couplet drawing
  • ● Top of frons brown or black with metallic blue-green reflections
a ↑
b ↓
  • couplet drawing
  • ● Top of frons yellow with dark T-mark, or black with pair of yellow spots

4  
  • Corduliidae: Key couplet 8 of 11

  • couplet drawing
  • ● Abdominal tergum 7 extensively black above, yellowish at sides

    ⇒ species: Tau Emerald (Hemicordulia tau)
a ↑
b ↓
  • couplet drawingcouplet drawingcouplet drawing
  • ● Basal half or more of abdominal tergum 7 yellow, with or without narrow, mid-dorsal black line

Australian distribution