Two testimonials of sightings exist that were done near the Dongu-Mataba (tributary of the Ubangi River) in The Republic of the Congo. The first was done in 1961; the second ten years later in 1971 by pastor Joseph Ellis. He estimated the length of the (visible) tailpart as 10 meters long (equal to his dugout, no neck or head could be seen), and a diameter of 0.5 to 1 meter. Its color was tending to greyish-brown. When back in the village, it appeared that the subject was taboo. The above and other sightings were gathered by University of Chicago biologist Roy P. Mackal, who led two expeditions to the Likouala swamps in the Republic of Congo, while searching for the Mokele-mbembe. Mackal concluded that the animal has a low-slung body, and therefore is more like a lizard than a snake, as "Ellis was positive the animal never raised itself sufficiently after leaving the water". Mackal also noted that the animal's triangular- or diamond-shaped ridges were similar (but smaller) to those from the Mbielu-Mbielu-Mbielu, but not the animals themselves. This is a common misreading from his book and mixed up at a lot of webpages.
Possibly the same animal is described in the 1958 book On the Track of Unknown Animals by Bernard Heuvelmans. In 1928, a snakelike animal called Ngakoula-ngou or Badigui was reported in the Ubangi-Shari area. This report was made by game inspector Lucien Blancou, who later in 1954 also made the first report of the Emela-Ntouka. According to this report, it killed a hippo in the Brouchouchou river without leaving any sign of a wound. It also crushed a manioc field, causing tracks from 1 to 1.5 meter wide.
Similar reports from 1932 (at Bouzoum) and 1934 exist, in which it is named Diba, Songo, Mourou-ngou and Badigui. In the 1934 report, an old man had especially come to see Blancou, as he was told that he showed interest in the animal. The old man narrated that in about 1890 he was fishing in the Kibi stream (Bakala district), and saw the Badigui eating from a tree, called "roro". He described the neck to be "as thick as a man's thigh", and the underneath of the neck was lighter colored. He could not see the full body, only about 8 meters of the neck. He also said "it does not frequent places where you find hippos, for it kills them". Finally in 1945, the animal's tracks were spotted near Ndélé, by Blancou's gun carrier.
- Chaboud (3 November 2000). "Nguma-monene". Everything2.
- Mackal, Roy P. A Living Dinosaur? In Search of Mokele-Mbembe; Leiden: E.J. Brill, 1987: ISBN 90-04-08543-2
- "Formerly Extinct". American Monsters. Archived from the original on 20 September 2016.
- Nguma-monene at cryptozoology.net