The Slender Bottletail (Olpogastra lugubris) is an unmistakable species and it is the only member of its genus. 
Both sexes are similar in appearance and easily recognised by their long and very thin abdomens. 
The base of the abdomen is noticeably swollen.

Murchison Falls River Lodge, Murchison Falls National Park, Uganda, 13 September 2025