15 Sarkidiornis melanotos illustrations Images: PICRYL Public Domain Media Search Engine Public Domain Search The knob billed duck (Sarkidiornis melanotos) aka African comb duck, is found in tropical wetlands in Sub Saharan Africa, Madagascar and the Indian Subcontinent from northern India to Laos and extreme southern China. Avise's Birds of the World This bird wears its crown not of feathers, but of horn. The Knob billed Duck (Sarkidiornis melanotos), also known as the Comb Duck, is one of the most unmistakable waterfowl in the world.