Slender Pintail, Acisoma variegatum, Dunpylstertjie

Short Description:

Slender Pintail, Acisoma variegatum, Dunpylstertjie is very small to small, mosaic bluish grey, greenish yellow and black, with bulbous (spindle shaped) abdomens that taper sharply at mid length, becoming black and ending in cream to light blue appendages.

 Family Libellulidae Leach, 1815

More images:

Click on all images to enlarge or view more

Key identification features:

Male:

• Face various light colours and black stripes. Labrum cream with basal central black dot. Anticlypeus pencil grey. Postclypeus light blue. Frons with black band in lower part, some black above and at sides, light blue centrally. Head black above.
• Eyes bright turquoise.
• Thorax light bluish grey, covered with myriad of irregular black lines and dots above and at sides. Dorsal thorax Grey blue but yellowish brown and green when young.Wings clear, with dark brown patch in hind area of hindwing. Pterostigmas relatively long (3 mm), whitish, slightly transparent.
• Wings clear with basel amber patch
• Abdomen unusual spindle-shaped. Segments 1 to 4 slightly swollen, contrasting with s 5 to 10 which are narrow. S 1 to 7 light bluish grey with black markings, including dorsal stripe. S 8 to 10 black. S 6 is 3× as long as high. S 6 and s 7 is approximately equal in length     Lateral abdominal carina partially white. 
  
• Appendages  white above, black below.

Female:

• Similar in shape as male but abdomen broader.
• Young males and females similar
• Pruinose to grey with very little detail visible with age
• Eyes stray coloured greenish above with light greenish white below with light blue streaks.
• Thorax (dorsal) and dorsal abdomen is straw coloured to greenish yellow with dark brown and blackish markings Thorax in lateral view greenish yellow above becoming light yellowish green becoming light whitish blue below.
• Wings clear who. Basel amber patch. Pterostigmas light grey.
• Abdomen underside of segments 1 to 3 bluish. Abdomen Segments 1 to 4 swollen, contrasting with segments 5 to 10 which are narrow. S 1 to 7 light bluish grey with black markings, including dorsal stripe. S 8 to 10 black. S 6 is 3× as long as high. S6 and s7 is approximately equal in length  

Habitat:

• Occur at pools, pans, sunny and especially grassy marshes and still reaches of (slow flowing) rivers with a high density of lilies, sedge and grasses.
• From 0 to 1700 m above sea level.

Behaviour:

• Flight is almost wasp-like as it darts over the floating vegetation, frequently settling, usually at least a metre from the bank

Compared with other species:

• Acisoma variegatum (Slender Pintail)   has overall a much lighter and more slender appearance than A. inflatum (Stout Pintail) 
• The black markings on A. inflatum (Stout Pintail) abdomen segments 1-5 are distinctly more black. compared to
• A variegatum (Slender Pintail) abdomen segment 6 is 3× as long as high.(side view). S6 and s7 is approximately equal in length. (Male Female ) A. inflatum (Stout Pintail) abdomen segment 6 is 2½ x as long as high. S6 is shorter (about  ¾) than s7   The difference in S6 - 7 is the primary diagnostic feature when not in hand
• The blue mark on S 7  A variegatum (Slender Pintail)   is a long slender pointed forefinger like pattern . On A. inflatum (Stout Pintail) it is short and stubby
• The blue marking on s 7 is long slender Acisoma variegatum 1-5 less swollen than s1-5 of  A. inflatum
• A. inflatum   has more extensive black markings on the abdomen than the Acisoma variegatum 
• Side view the lower region of segment 4 is black in the A. inflatum but whitish in the A. variegatum

 Distribution

South Africa:

• Lowland KZN, MP, LP and north eastern NWP. 

Africa:

• Democratic Republic of the Congo; Ethiopia; Kenya; Malawi; Mozambique; Republic of South Africa; Rwanda; Tanzania; Uganda; Zambia; Zimbabwe;

Further reading

Websites of interest

• The IUCN Red List of Threatened Species Least Concern  
•    A Visual Guide to the Damselflies and Dragonflies of South Africa