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.

#	Family	Species	Couplet No.
	Corduliidae	Tau Emerald (Hemicordulia tau)	Corduliidae: Key couplet 1 of 11 ● Hypertriangles generally free b ↑ Corduliidae: Key couplet 2 of 11 ● 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 ● Top of frons yellow with dark T-mark, or black with pair of yellow spots b ↑ Corduliidae: Key couplet 8 of 11 ● Abdominal tergum 7 extensively black above, yellowish at sides ⇒ species: Tau Emerald (Hemicordulia tau) a ↑
1			Corduliidae: Key couplet 1 of 11 ● Hypertriangles of both wings crossed ⇒ species: Metallic Tigerhawk (Pentathemis membranulata) a ↑ b ↓ ● Hypertriangles generally free
2			Corduliidae: Key couplet 2 of 11 ● 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 ↓ ● 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 ● Top of frons brown or black with metallic blue-green reflections a ↑ b ↓ ● Top of frons yellow with dark T-mark, or black with pair of yellow spots
4			Corduliidae: Key couplet 8 of 11 ● Abdominal tergum 7 extensively black above, yellowish at sides ⇒ species: Tau Emerald (Hemicordulia tau) a ↑ b ↓ ● Basal half or more of abdominal tergum 7 yellow, with or without narrow, mid-dorsal black line