Hippopotamidae Author Don E. Wilson Author Russell A. Mittermeier text 2011 2011-08-31 Lynx Edicions Barcelona Handbook of the Mammals of the World – Volume 2 Hoofed Mammals 308 319 book chapter 3347 10.5281/zenodo.5719835 a6dc4656-3bbb-411f-b31e-8b8d7ca5c101 978-84-96553-77-4 5719835 2 . Pygmy Hippopotamus Choeropsis liberiensis French: Hippoptame nain , Hippopotame Pygmée / German: Zwergflusspferd / Spanish: Hipopdtamo pigmeo Other common names: Heslop's Pygmy Hippopotamus (heslopi) , Niger Delta Pygmy Hippopotamus (heslopi) Taxonomy. Hippopotamus liberiensis Morton, 1849 , Liberia . Although previously included in the genus Hexaprotodon , a recent review of the taxonomy and phylogeny of Hippopotamidae restricted the definition of Hexaprotodon to extinct Asian hippos and revalidated Choeropsis for the extant Pygmy Hippo. An endemic subspecies, the Niger Delta or Heslop’s Pygmy Hippopotamus (heslopi), was reported based on osteologic specimens obtained by Heslop in 1945 when examined years later by Corbet in 1969 and Coryndon in 1977 due to variations in cranial anatomy. As no complete specimen was ever brought into captivity, and the description of this subspecies is based on only one skull, mandible, and skin, the veracity of this subspecies is difficult to confirm. Despite this scarcity of literature, there is general agreement that if this subspecies existed it is possibly extinct in Nigeria , as the last wild animal in that region was seen in 1943. Two subspecies recognized. Subspecies and Distribution. C.l.liberiensisMorton,1849—Guinea,SierraLeone,Liberia,IvoryCoast. C. l. heslop: Corbet, 1969 — Nigeria (possibly extinct). Descriptive notes. Head-body 150-175 cm, tail 20 cm , shoulder height 75-100 cm; weight 160-270 kg. Distinctly barrel-shaped body, with somewhat longer limbs and more proportionate head than Common Hippo. Skin is gray and appears greasy. Body virtually hairless except on snout and tail. Feet have four toes. Dental formula: 12/1, C1/1,P 3/3, M 3/3 (=2)= 34. Habitat. Found in densely forested lowland areas of West Africa. Preferred habitat is streams in forest and in some areas they have been associated with low-hanging Rhaphia palm trees. Food and Feeding. Feeding has not been studied in detail in wild populations, but they are believed to browse, feeding on leaves, aquatic plants, and fallen fruit as well as roots and tubers. Thick lips used to tear and remove forage. Breeding. Most information comes from captive animals, as there is no accurate data on reproduction, including breeding season, for wild populations. Sexual maturity occurs at about 4-5 years of age. From studies of captive animals, the estrous cycle averages 35-5 days with estrus itself lasting 24-48 hours. No obvious seasonality in reproduction. Mating occurs on land and in water, typically 1-4 times during an estrous period. Gestation approximately six months, resulting in a single young (rarely twins) weighing about 5 kg . Calves may be cached or hidden when first born, but can readily swim shortly afterwards. Activity patterns. Most active at night but not limited to night-time hours. Thought to be associated with rivers or streams. Movements, Home range and Social organization. More active at night, following game trails or tunnel-like paths through dense forest vegetation. Associated with rivers and streams, butless reliant on a single water source than Common Hippos. Home range estimated 2 km ?® for males and 0-5 km? for females. May den or rest in dense vegetation during the day. Status and Conservation. CITES Appendix II. Classified as Endangered on The [UCN Red List. Primary threats are widespread habitat loss to logging and clearing for agriculture. Opportunistic bushmeat hunting has been reported in more fragmented areas and is believed to pose an additional threat to species viability. A population estimate in the early 1990s stated that there were less than 3000 individuals remaining. Although the true population size is unknown, even that estimate may be high and populations most likely are continuing to decline such that a 20% decrease over the course of the next 20 years is not without reason. Bibliography. Boisserie (2005), Boisserie & Lihoreau (2006), Boisserie, Lihoreau & Brunet (2005), Boisserie, Zazzo et al. (2005), Corbet (1969), Coryndon (1977), Eltringham (1993, 1999), Lewison & Oliver (2008a), Olivier & Laurie (1974), Robinson (1970, 1981), Roth et al. (2004).