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

Chorismagrionidae
Chorismagrion risi

Major Group: Insecta
Order: Odonata
Family: Chorismagrionidae
Genus: Chorismagrion
Species:
risi
This family is endemic to Australia and is represented by a single species, Chorismagrion risi.

Descriptive Features:

  • head wider than deep, frons rounded
  • labium just showing from beneath head as viewed dorsally, setae absent
  • antennae very long, 5-segmented, scape short, pedicel nearly 4X longer, segment 3 1/3 length of pedicel, other segments progressively shorter, segments 3- 5 black except at apices
  • vertex marbled with brownish grey, ocelli outlined in this colour; occiput shallowly concave, bulging and globular behind eyes where it is finely spined
  • labial mask kite-shaped, deep black in colour except the lobes
  • lateral lobes with a long robust movable hook and terminating in 2 stout teeth, the innermost the longer and acuminate at apex
  • medial lobe projecting as 2 rounded lobes separated by a deep but closed fissure, the free border finely dentate
  • prothorax oval, marked with a parallel pair of short longitudinal middorsal stripes of black, as well as its sides
  • thorax bulky, blackish except on middorsum and medial borders
  • legs rather long and slender, ridged but without armature save some bordering minute spines
  • coxae, base and apex of femora as well as 2 medial rings black, tibiae with 2 black rings
  • abdomen cylindrical, tapering, pale on dorsum and blackish beneath and with a narrow blackish band extending along each side from end to end
  • caudal gills broadly oval, rather obtusely pointed at apices, median gill hardly shorter than lateral gills, all gills black except a conspicuously pale yellowish apex, held vertically and closely
  • Total length: 17 mm
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    Chorismagrion risi

    Taxonomic Checklist:
    Chorismagrion risi
    Morton, 1914 

    Distribution: N Qld

    Sensitivity Rating: none

    Functional Feeding Group: predators

     

    tributary to Barron River, Kuranda Qld

    Ecology: Adults are commonly known as 'relicts'.
    Instream habitat: Chorismagrion risi nymphs occur in rainforest streams and are found under cobble-sized rocks and leaf-packs in slow-flowing areas.
    Feeding ecology: Nymphs are predators.
    Habit:
    Life history:

     

    Information Sources: Fraser 1956, Houston 1988, Theischinger & Hawking 2006

     

     

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