Stout Pintail Acisoma inflatum Dikpylstertjie.
Stout Pintail, Acisoma inflatum, Dikpylstertjie 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 appendages..
Previously grouped with Acisoma variegatum (Slender Pintail) as one species, Acisoma panorpoides (Grizzled Pintail).
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Key identification features:
- Face has various light colours and black stripes. Labrum is cream with basal central black dot. Anteclypeusis pencil grey.
Postclypeusis light blue. Frons has a black band in lower part, some black above and at sides and light blue centrally. Head is black above.
- Eyes are bright turquoise.
- Thorax is light bluish grey, covered with myriad of irregular black lines and dots above and at sides.
- Wings are clear, with dark brown basil patch in hind wing. Pterostigmas are relatively long (3 mm), whitish, slightly transparent.
- 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 2½ x as long as high. S6 shorter in length than s7
- 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 2½ x as long as high. S6 shorter in length than s7 Lateral abdomen carina all black
Compared with other species:
- Acisoma 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 than s7
- A. inflatum has more extensive black markings on the abdomen than the A. variegatum
- Side view the lower region of segment 4 is black in the A. inflatum but whitish in the A. variegatum (Male Female )
- Despite marked differences in mature males, females and fresh males are less distinctly marked and may be confused
Distribution and habitat:
Their flight is almost wasp-like as it darts over the floating vegetation, frequently settling, usually at least a metre from the bank.