Tropical Bluetail. Hemelstertjie.
Previously known as Marsh Bluetail.
Ischnura senegalensis (Rambur, 1842)
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Tropical Bluetail, Ischnura senegalensis, Genus Ischnura, Family Coenagrionidae small sized with apple green, blue, greenish blue and black markings on thorax and very distinctive bright cobalt blue markings on the abdominal tip.
Key identification features:
- Face greenish blue and black with fine covering of whitish hairs. Labrum green or greenish blue with black base and edged in yellow. Anteclypeus green or greenish blue. Postclypeus shiny black, finely edged in light green. Frons light green. Head dull black from above with bronze sheen, with two round bright blue postocular spots.
- Eyes black above, greenish blue below.
- Neck shiny black above, green on collar and below. Thorax with distinct hairy down over shiny black surface with mauve sheen, sharply defined yellowish to greenish (sometimes blue) stripes, sides bright light green or greenish blue (sometimes sky blue).
- Wings clear. Pterostigmas blackish in inner half, bright blue in outer half.
- Segments 1 to 7 shiny black above, segment 2 with distinct metallic sheen. Fine bright blue ring present between segments 1 and 2. Segment 1 and especially segment 2 with round blue patches that are continuous with the light area below when seen from side. Segments 3 to 7 buff below, segment 8 bright blue, segment 9 shiny black above and blue below, segment 10 shiny black above and buff below. Hind margin of segment 10 with raised process with two peaks.
- Inferior appendages prominent, pointed, with black tips.
- This species is often parasitized by small mites (Arrrenurus spp. Small orange ball like, sometimes tightly packed against each other)
- Females are very variable in colour with two primary colour forms one of which is bluish and very similar to male. The other form is bright rufus brown and black, mostly black along thorax and last eight segments of abdomen from above, thorax almost entirely Rufus from side. Postclypeus shiny black and top of head metallic black contrasting strongly with pale band running across front of frons in both forms.The orange form (immature) is more distinctive. Blue, green brown and black variations have been recorded
Compared with other species:
- Easily mistaken for Sprite (Pseudagrion Group A and Group B sp.) or Bluet (Africalagma sp. or Azuragrion sp.) but s8-10 is diagnostic on I. senegalensis.
Distribution and habitat:
- Common and widespread in South Africa. Also found in the arid areas permitting the preferred habitat is available.
- Standing and often temporary waters, rivers, streams and possibly large lakes in open landscapes. Often with emergent and aquatic vegetation. Tolerates conditions avoided by other species, e.g. rather saline, with high organic input from animals or near hot springs. Absent from forested areas. From 0 to 2700 m above sea level, but mostly below 1800.
- It is conspicuous when it flits and rests among reeds, sedge and grasses in marshy areas. Mating pairs are common.