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 Major Groups | Insecta (insects) | Odonata (dragonflies, damselflies) | Hemicorduliidae


Major Group: Insecta
Order: Odonata
Family: Hemicorduliidae (formerly part of Corduliidae)

Descriptive Features:

  • posterior margin of head rounded
  • eyes variably protruding laterally
  • prementum concave (ladle-shaped), bearing 9-14 pairs of setae
  • base of prementum ventrally with distinct midline groove
  • labial palps broadened distally, forming mask in front of head when closed
  • labial palps with 8-9 dentations, with 7-9 setae
  • frontal plate not produced beyond scape
  • prementum deep, bottom concave
  • mentum length subequal to width
  • lateral spines on abdominal segment 9 not extremely long, not more than 3X middorsal length of segment 9
  • larvae usually stout
  • abdomen convex in lateral view
  • abdomen with 3 conspicuous substantial triangular processes at tip of abdomen, forming anal pyramid surrounding anus
  • Total length: 16.0-24.0mm
    • Taxonomic Checklist: Genera

      Distribution: Australia wide

      Sensitivity Rating: SIGNAL grade 5

      Functional Feeding Group: predators

      Ecology: Adults are commonly known as 'round winged or modern emeralds'.
      Instream habitat: Hemicordulid larvae inhabit fast or sluggish rivers, riverine pools, lagoons, lakes, swamps and permanent ponds. They are found amongst gravel in streams as well as plants in ponds. Hemicordulia tau tolerates a wide thermal range from the cold waters of Lake Eucumbene, NSW to warm temporary waters near Perth, WA.
      Feeding ecology: Larvae are predators feeding on aquatic insects such as chironomid larvae, Hemiptera and other Odonata larvae.
      Habit: Adults are vagrants.
      Life history: The following information relates to Hemicordulia tau. Larvae undergo nine instars, however other species may have up to 12 larval instars. Hemicordulia tau can over winter in cold water permanent refuges, usually at the fifth to eighth instar stage. Final instar larvae have been observed to climb up to five metres and walk across land to emerge. Adults usually emerge in December, but may be collected from September to November or February to April. The number of life cycles per year increases with an increase in available nutrition and temperatures. Typically H. tau is a univoltine summer species with a life cycle of about 41 days.
      Information Sources: Theischinger & Hawking 2006, Hawking & Theischinger 1999, Farragher 1980
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