Navy Dropwing, Trithemis furva, Blouvalvlerkie

Short description: 

Navy Dropwing, Trithemis furva, Blouvalvlerkie is medium sized and all dark blue with yellow facial markings.

Family Libellulidae Leach, 1815

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More mages:

 Wing Venation

Explain complete and incomplete Ax veins

Key identification features:

Male:

• Face light yellowish brown, dark brown and black.      Labium pale yellow with wide central black stripe. Labrum black. Anteclypeus light creamy to brown. Postclypeus dark brown at back, light yellow brown at sides. Frons dark brown in front, light yellowish brown at sides. Frons above and top of head dimpled, metallic bluish purple
• Eyes dark purplish brown, lighter below. 
• Thorax dark blue can have a purplish undertone   
• Abdomen dark blue yellow and black when young. When old becoming dark blue with the yellow stripes fading with age to become dark blue with age. Dorsal abdomen with narrow black stripe broadening slightly towards segment 10, becoming dark blue with age. .
• Wings are clear with very small basal amber patch on hindwings. Ax veins dark.
  
• Both sexes the last Ax vein is mostly incomplete. This may vary from specimen to specimen where one wing Ax vein may be complete (probably the right wing)  Pterostigmas brownish black, 3 mm.
• Young male and female alike.

Females:

• Yellowish with black markings.
• Thorax has black zigzag line alongside.
• Abdomen with narrow black stripe running along its top.
• Wings each slightly smoky around nodus and tip, Hindwings with small basal splash.
• Pterostigmas yellowish brown, becoming dark brown with age.

Habitat:

• Mostly streams, but also rivers, in open landscapes and open areas in forest. Often with emergent vegetation and rocks. 
• From 0 to 2500 m above sea level, but mostly below 2000.

Behaviour:

• Mostly perches on rocks, where it looks almost blackish, or on twigs and reeds at water's edge.
• Female usually away from the water, among tall grass or small bushes.

Compared with other species:

• The Navy Dropwing, T. Furva  and the Highlands Dropwing, Trithemis dorsalis,  is virtually indistinguishable in the field.
• T. Furva  Ax veins are dark .Trithemis dorsalis,  Ax veins yellow/cream bur may darken with age 
• A guide however, is firstly the habitat, being usually rocky rivers at low elevations. Secondly pterostigmas that are usually all brownish black, with no white end-veins, and thirdly, a female which has a single zig-zaggy thoracic side stripe.
• Also, the blue of the male is not so colourful and more blackish than in T. dorsalis.
• It is essential to examine secondary genitalia, with scythe-like hamules and bristle tuft on anterior lamina.
  Link to similar species
  Trithemis donaldsoni (Denim Dropwing)    Trithemis dorsalis (Highland Dropwing)

Learn More about other Dropwings, (Trithemis) Species

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Distribution

  South Africa:

•  Most of South Africa but with insufficient records for the Dry central parts.

Africa:

• Angola; Botswana; Cameroon; Chad; Democratic Republic of the Congo; Equatorial Guinea; Eritrea; Ethiopia; Kenya; Lesotho; Malawi; Mozambique; Namibia; Nigeria; Republic of South Africa; Somalia; Sudan; Swaziland; Tanzania; Uganda; Zambia; Zimbabwe

Further reading:

Websites:

• A Visual Guide to the Damselflies and Dragonflies of South Africa
• The IUCN Red List of Threatened Species  Least Concern
• Odonata Atlas of Africa VMU Number 661790
  
• Africa Dragonflies & Damselflies Online