Knob Billed Male Duck: (Sarkidiornis melanotos) or African comb duck or comb duck is a type of duck.The male is much larger than the female, and has a large black knob on the Avise's Birds of the World Photos and pictures of: knob billed duck (Sarkidiornis melanotos), Sabi Sands, Greater Kruger National Park, South Africa The Africa Image Library African Comb Duck or Knob Bill (Sarkidiornis m. melanotos). Adult male in breeding plumage, standing on one foot in shallow water. Okavango Delta. Botswana. Stock Photo Alamy