The Nigerian pygmy hippopotamus ranged in the Niger River Delta, especially near Port Harcourt, but no reliable reports exist after the collection of the museum specimens secured by I. R. P. Heslop, a British colonial officer, in the early 1940s. It is probably extinct. The subspecies is separated by over and the Dahomey Gap, a region of savanna that divides the forest regions of West Africa. The subspecies is named after I. R. P. Heslop, who claimed in 1945 to have shot a pygmy hippo in the Niger Delta region and collected several skulls. He estimated that perhaps no more than 30 pygmy hippos remained in the region.