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This study provides a complete morphological description and functional analysis of the carpal bones of the endemic pygmy hippopotamus Phanourios minor, derived from the Upper Pleistocene site of Ayia Napa. From this deposit, numerous skeletal remains of this fossil hippo have been collected, making the locality one of the richest in Cyprus. The carpal bones were compared with those of extant hippopotamuses, to determine the changes that occurred in the fossil hippo. Examination of the elements showed that Phanourios presented some important features that were common among the endemic fossil ungulates of the Mediterranean islands. The carpal bones display a proximal-distal compression due to shortening of the distal part of the leg, due to the new ecological island conditions. However, they are robust with rough areas for strong muscular and ligament insertions, providing stability to the carpal joints, and low speed movement to the animal. The great flexor capabilities, and the limitation in ulnar deviation of the carpus, indicate that P. minor had increased agility in the sagittal plane and restricted transverse movements, while the suggestion of a more unguligrade stance for the species is ambiguous. Thus, the endemic Cypriot hippos developed specialized locomotion, suitable for walking on the rugged terrain of Cyprus, which seems to be different from that of its extant counterparts.

The use of life tables in age-graded mandibles of the endemic pygmy hippopotamus Hippopotamus minor from Aetokremnos Cyprus suggests that death occurred by natural causes such as accidents, genetic abnormalities and endemic diseases rather than catastrophic causes. Comparison of H. minor and modern Hippopotamus amphibius life tables suggests the birth of one offspring per female per year and the occurrence of mating and birth seasons. Hunting by prehistoric humans whose tools were found in proximity with the hippopotamus bones is not justified by the life tables that have been produced. The use of the wet rockshelter of Aetokremnos as a living area during the day, in the same way that extant H. amphibius use lake water, is instead proposed as a probable explanation for the extensive accumulation of bones.

The pygmy hippopotamus is phylogenetically related to members of both the Suidae and Cetacea. However, differences in their habitats may have resulted in variation in the anatomy and physiology of the ocular adnexa between these species. Therefore, this study focuses on the identification of accessory organs of the eye, which are typical for the pygmy hippopotamus and are comparable to organs present in mammals related to it. Moreover, the secretions produced by the superficial gland of the third eyelid, the deep gland of the third eyelid and the lacrimal gland were examined, as they ensure eyeball protection. In the upper and lower eyelids, numerous serous glands where identified, which were typical for the pygmy hippopotamus and similar as in the Cetacea. This study enabled to identify additional folds in the eyelids of the pygmy hippopotamus. Lymphoid follicles and diffuse lymphocytes were not found in the lymphoid region in the upper or lower eyelids and the third eyelid, which was most likely caused by the age of the studied hippopotamuses. An accurate histochemical analysis revealed that the secretions of the pygmy hippopotamus are very similar to the Sus scrofa. The structural differences between the pygmy hippopotamus and representatives of Cetacea are most likely caused by the fact that most of Cetacea live in saltwater and are exposed to more frequent fluctuations in water temperature compared to the pygmy hippopotamus, which lives in fresh water and does not lead a migratory lifestyle like the Cetacea.

International audience; Hippopotamoids are herbivorous mammals that originated in the late middle Eocene. This taxon includes animals with a great variety of sizes and body proportions, from small and gracile forms with slender limbs to heavy massive ones. Many hippopotamoids have previously been considered semi-aquatic but recent studies have highlighted a diversity of ecologies. This study focuses on bone microanatomy, one of the various proxies that enable inferring the ecology of extinct taxa. The comparative analysis of the inner structure of the stylopod bones in various hippopotamoids, based on both transverse and longitudinal virtual sections, highlights a diversity of patterns and clarifies previously proposed hypotheses about the ecology of the sampled hippopotamoids. The filling of the medullary area by spongious deposits in the pygmy hippopotamus, Choeropsis liberiensis, appears associated with frequent incursions into the water by an animal that essentially forages in forests. The common hippopotamus, Hippopotamus amphibius, which spends most of the day submerged in water, shows a greater filling of the medullary area by spongious bone and a thicker cortex. These observations coupled with comparisons with diverse terrestrial and semi-aquatic mammals of various sizes confirm that semi-aquatic lifestyle and heavy weightbearing are associated with similar microanatomical specializations causing an increase in bone mass. However, for a given mass, comparisons enable determining if an additional increase in bone compactness occurs, as in Hippopotamus amphibius, in which case a semi-aquatic lifestyle could be inferred. Accordingly, this study suggests an essentially terrestrial lifestyle for Microbunodon minimum, Bothriodon velaunus, Elomeryx borbonicus, Merycopotamus medioximus, Paenanthracotherium bergeri, and probably also Saotherium cf. S. mingoz, a slight degree of water dependence in Brachyodus onoideus, and a stronger one in Libycosaurus bahri and Hexaprotodon garyam, though less intense than in Hippopotamus amphibius. Comparisons with other large terrestrial and semi-aquatic taxa, and based on a large part of the diaphysis, are required to better decipher the microanatomical changes associated with a semi-aquatic lifestyle from those linked to loading in heavy quadrupedal mammals.

A multiparous pygmy hippopotamus (Choeropsis liberiensis) dam produced three consecutive calves that died acutely at 13-15 wk of age from bacterial sepsis, for which diagnostic and therapeutic intervention was not possible. Streptococcus iniae (Cases 1 and 3), Escherichia coli (Case 2), and an unidentified member of the family Pasteurellaceae (Case 1) were identified in postmortem tissues through bacterial culture followed by standard and molecular identification methods. After the loss of two calves, a series of vaccinations were administered to the dam during the third pregnancy to enhance transplacental and colostral transfer of antibodies to the calf. The third calf did not survive, and the source of the bacterial infection in these three calves was undetermined. Prior to and after the birth of the fourth calf, nutritional and nutraceutical supplements were provided to the dam and calf. Additionally, pest control around the barn was enhanced. The fourth calf survived. Pygmy hippopotamus calves at the age of 13-15 wk may have increased susceptibility to bacterial infection, possibly due to waning maternally derived immunity. The findings in these cases, combined with a previous association of S. iniae in pygmy hippopotamus deaths, suggest that this bacterium is an especially important pathogen of the endangered pygmy hippopotamus.

MC5R is one of five melanocortin receptor genes found in placental mammals. MC5R plays an important role in energy homeostasis and is also expressed in the terminal differentiation of sebaceous glands. Among placental mammals there are multiple lineages that either lack or have degenerative sebaceous glands including Cetacea (whales, dolphins, and porpoises), Hippopotamidae (hippopotamuses), Sirenia (manatees and dugongs), Proboscidea (elephants), Rhinocerotidae (rhinos), and Heterocephalus glaber (naked mole rat). Given the loss or diminution of sebaceous glands in these taxa, we procured MC5R sequences from publicly available genomes and transcriptomes, supplemented by a newly generated sequence for Choeropsis liberiensis (pygmy hippopotamus), to determine if this gene remains intact or is inactivated in association with loss/reduction of sebaceous glands. Our data set includes complete MC5R sequences for 114 placental mammal species including two individuals of Mammuthus primigenius (woolly mammoth) from Oimyakon and Wrangel Island. Complete loss or inactivation of the MC5R gene occurs in multiple placental lineages that have lost sebaceous glands (Cetacea, West Indian manatee, African elephant, white rhinoceros) or are characterized by unusual skin (pangolins, aardvarks). Both M. primigenius individuals share inactivating mutations with the African elephant even though sebaceous glands have been reported in the former. MC5R remains intact in hippopotamuses and the naked mole rat, although slightly elevated dN/dS ratios in these lineages allow for the possibility that the accumulation of inactivating mutations in MC5R may lag behind the relaxation of purifying selection. For Cetacea and Hippopotamidae, the absence of shared inactivating mutations in two different skin genes (MC5R, PSORS1C2) is consistent with the hypothesis that semi-aquatic lifestyles were acquired independently in these clades following divergence from a common ancestor.

The effectiveness of protected area management is a major concern. In Taï National Park, Côte d'Ivoire, recurrent human pressure challenges the ability of law enforcement authorities to protect wildlife. During 2010–2015 we studied the implementation of law enforcement in the Park to determine (1) the potential for improvement of the protection of large mammals and (2) the minimum patrolling effort needed to obtain increases in their populations. We recorded presence of large mammals and illegal activities in two areas within the Park, the research area (210 km2) and the rest of the Park (5,150 km2), and compiled data about patrolling efforts from the Park authorities. Using a generalized linear mixed model we identified a relationship between increased patrolling effort and the relative abundance of large mammals, especially for monkey groups, pygmy hippopotamuses Choeropsis liberiensis and duikers. At low patrolling efforts duiker encounter rates remained stable, whereas rates of encounter with monkey groups and pygmy hippopotamuses decreased. Chimpanzee Pan troglodytes verus encounter rates were slower to respond and remained stable at higher patrolling effort, but decreased at low patrolling effort. Our findings suggest that a minimum of 1.32 patrol days per km2 over 2 years is required for chimpanzee and monkey populations to increase, whereas a patrolling effort of 0.48 days per km2 over 2 years would lead to an increase in duiker and pygmy hippopotamus populations. We maintain that the patrolling effort required to ensure an increase in wildlife can be estimated relatively precisely from multi-year biomonitoring programmes.

SUMMARYThe macroevolutionary transition from terra firma to obligatory inhabitance of the marine hydrosphere has occurred twice in the history of Mammalia: Cetacea and Sirenia. In the case of Cetacea (whales, dolphins, porpoises), molecular phylogenies provide unambiguous evidence that fully aquatic cetaceans and semiaquatic hippopotamids (hippos) are each other’s closest living relatives. Ancestral reconstructions further suggest that some adaptations to the aquatic realm evolved in the common ancestor of Cetancodonta (Cetacea+Hippopotamidae). An alternative hypothesis is that these adaptations evolved independently in cetaceans and hippos. Here, we focus on the integumentary system and evaluate these hypotheses by integrating new histological data for cetaceans and hippos, the first genome-scale data for pygmy hippopotamus, and comprehensive genomic screens and molecular evolutionary analyses for protein-coding genes that have been inactivated in hippos and cetaceans. We identified ten skin-related genes that are inactivated in both cetaceans and hippos, including genes that are related to sebaceous glands, hair follicles, and epidermal differentiation. However, none of these genes exhibit inactivating mutations that are shared by cetaceans and hippos. Mean dates for the inactivation of skin genes in these two clades serve as proxies for phenotypic changes and suggest that hair reduction/loss, the loss of sebaceous glands, and changes to the keratinization program occurred ~16 million years earlier in cetaceans (~46.5 Ma) than in hippos (~30.5 Ma). These results, together with histological differences in the integument and prior analyses of oxygen isotopes from stem hippopotamids (“anthracotheres”), support the hypothesis that aquatic adaptations evolved independently in hippos and cetaceans.

The pygmy hippopotamus (Choeropsis liberiensis) is an IUCN Red List Endangered species (CITES Appendix II) that has been housed in zoological collections since 1912. As wild populations continue to decline throughout the species' range, successful ex situ breeding and management, including an understanding of morbidity and mortality, are of utmost importance. This study is the first comprehensive review of mortality data from the captive population since 1982 and significantly expands on previous analyses. We solicited necropsy reports from 129/187 zoological institutions worldwide that currently or previously held pygmy hippos and received data for 404 animals (177 ♂, 220 ♀, 7 undermined sex), representing 43% of pygmy hippos that have died in captivity. Mortality in neonates was primarily due to perinatal causes (51.8%-stillbirth, failure to thrive, weakness, poor suckling reflex, maternal neglect) or parent-inflicted trauma (28%). Common causes of mortality in adult and geriatric animals included cardiovascular disease (16%), degenerative musculoskeletal conditions (10%), obstructive gastrointestinal disease (9%), and renal insufficiency (13%), sometimes associated with advanced polycystic kidney disease (PKD). Although not the direct cause of mortality, a number of adult and geriatric pygmy hippos were also overweight to obese. Infectious causes of mortality in included leptospirosis and encephalomyocarditis virus, the latter usually presenting as acute death due to cardiovascular demise. This comprehensive overview presents a useful guide for recommendations in preventative veterinary care and for improved husbandry and management of pygmy hippos in captivity. Zoo Biol. 35:556-569, 2016. © 2016 Wiley Periodicals, Inc.

The family Hippopotamidae is comprised of two genera with two living species, the common hippo (Hippopotamus amphibius) and the pygmy hippo (Choeropsis liberiensis). Unlike the common hippo, the karyotype of C. liberiensis has not yet been investigated via cross-species chromosome painting methods. We established chromosomal homologies between the pygmy hippo, pig, and cattle by fluorescence in situ hybridization using whole chromosome, arm-specific, region specific, and bacterial artificial chromosome (BAC) probes. Probes from the 18 pig autosomes painted 45 conserved chromosomal segments in the pygmy hippo genome. The pygmy hippo and cattle homology map was deduced from our hybridization results of painting probes to pygmy hippo chromosomes with a combination of previously published dromedary hybridization data. On the pygmy hippo and cattle homology map, 29 cattle autosomes revealed 39 conservative segments on pygmy hippo chromosomes. For a more detailed structural analysis of genome rearrangements and X chromosome structure, we used cattle region specific and BAC probes. Our report demonstrates that cattle probes are useful not only in comparative studies within Ruminantia, but also in more phylogenetically distant Artiodactyla species.

The contribution of protected areas to biodiversity conservation is well attested but many taxa in many regions remain dependent on the unprotected wider landscape. To develop conservation plans for large mammals such as the Endangered pygmy hippopotamus Choeropsis liberiensis of West Africa's Upper Guinea Forests it is critical to understand the importance of unprotected land. Despite being a conservation priority, little is known about the habitat associations of this species, or its distribution across its range. Through a combination of field surveys, species distribution models and community questionnaires we investigated the use of unprotected areas by the pygmy hippopotamus in the Sierra Leone–Liberia border region. We found signs of the species in 128 of 525 1-km2 cells surveyed. Our analysis suggested that the species is reasonably widespread in this region and is associated with major rivers. It occurred close to, but rarely within, large areas of intact forest, and 80.4% of pygmy hippopotamus signs were recorded outside protected areas. The expansion of the protected area network in this area is unrealistic in Sierra Leone and to some extent in Liberia, mainly because of anthropogenic pressure and the overlap of proposed protected areas with mining and logging concessions. Thus pygmy hippopotamus conservation activities in the region need to include programmes on community lands while maintaining a robust network of protected forests. Community-based conservation of the pygmy hippopotamus may prove valuable for other threatened and endemic species that are not confined to protected areas in this region.

Recent excavations at Akrotiri Aetokremmos, Cyprus, stirred up great excitement among students of Mediterranean Archaeology and palaeozoology, since they were presented as revealing for the first time on the island a large deposit of Pleistocene fauna - mainly pygmy hippopotamus - in association in artifactual material. It was further claimed that humans may have been responsible for the extinction of some of the endemic Cypriot fauna. A re-examination of the data from the site questions the existence of the ninth millennium BC hippopotamus hunters on Cyprus and addresses the more general issues of how archaeologists observe the archaeological record, give meaning to it, and reconstruct the human past.

This study aimed to evaluate the genetic and environmental factors affecting the survival of the pygmy hippopotamus (Choeropsis liberiensis) population kept in zoological gardens, including the estimation of the inbreeding level. Survival was examined at three time points: birth (0–1 days), 1 month (30 days) and 5 years of age. The data were obtained from the Zoological Information Management System, and covered observations on 1196 pygmy hippo, collected between 1873 and April 2016 and grouped into five geographical regions (Africa, Australasia, Europe, USA and Canada, and South America). The analyses were performed using LOGIT and PROBIT transformations of the binominal survival data. No statistically significant differences (P-value > 0.05) were observed between the results obtained from the two transformations. The survival of individuals was found to decrease with increased level of inbreeding, the most significant effect being on survival at birth. At all three survival time points the highest survival was observed among females. Additionally, the Australasia region showed the highest overall survival. We hypothesize that the environment, climate and similarity of local food to the native diet of pygmy hippo allows animals kept in zoological gardens in that region to perform better than in other regions. The results of this study indicated that it is necessary to exercise vigilance in reducing inbreeding as it negatively impacts survival. This can be achieved by continued efforts to maintain and improve genetic diversity through management of breeding and associated transfer of animals between zoological facilities to reduce relatedness in breeding pairs.

The aim of this study was to estimate the inbreeding level and its impact on offspring sex ratio in the pygmy hippopotamus population kept in zoological gardens. Records of pygmy hippopotamus born between 1873-2013 were extracted from the international studbook. Totally, 1357 individuals originating from 148 breeding units were included (individuals with unknown sex were omitted). The offspring sex ratio is defined as the number of sons to the total number of progeny of each dam and sire. Spearman's rank correlation was employed to examine the relationships between the inbreeding level and offspring sex ratio. Inbreeding coefficients and individual increase in inbreeding coefficients (included as a linear co-variable) were examined as well as the geographic region and birth period using general linear models. The average inbreeding coefficient was 5.39%. The following sex proportion was observed for the inbred population: 57% and 43% for females and males, respectively. A significant relationship between inbreeding level of parents and their offspring sex ratio were estimated for European zoological gardens, whereas in others geographic regions the dependencies were insignificant.

Social and reproductive systems remain among the main predictors affecting mammalian birth sex ratio. The two extant hippopotamus species differ in their social and reproductive systems. While common hippopotamus (Hippopotamus amphibius) form herds and tend to be polygynous, solitary living pygmy hippopotamus (Choeropsis liberiensis) are promiscuous. Although it is one of the most studied topics, only few empirical studies using large sample sizes have reported distorted birth sex ratio. We examined the birth sex ratio in both hippopotamus species using international studbooks including large data sets exceeding a thousand individuals (1138 for common hippopotamus and 1161 for pygmy ones). In both species, the birth sex ratio differed from 1:1. Whereas more males than females were recorded in common hippopotamus (53.9% males), the opposite was found in pygmy hippopotamus (41.5% males). We also found that the birth sex ratio was affected by individual dams in common hippopotamus, and by individual sires in pygmy hippopotamus. The most plausible explanation for differentially skewed birth sex ratios in both species may be related to differences in social and reproductive systems. Whereas the polygynous, sexually dimorphic common hippopotamus biased the birth sex ratio towards males, the promiscuous and sexually monomorphic pygmy hippopotamus skewed the sex ratio in favour of females. Our results are in line with recent studies showing that not only manipulation by the mother (in common hippopotamus), but also by the father (in pygmy hippopotamus), may be responsible for the birth sex ratio in different species.

An endangered species, the pygmy hippo (Choeropsis liberiensis Morton, 1849) has been housed in captivity since the early 1900s, but systematic, prospective research and peer-reviewed literature remain limited in comparison to other IUCN-listed, charismatic mega fauna. There are just over 350 animals in the ex situ population worldwide, so it is an uncommon resident in zoological collections compared to the larger, ‘common’ or Nile hippo (Hippopotamus amphibius). Most published information for the pygmy hippo constitutes descriptive accounts of first-hand experiences in various zoological institutions. Here we review, analyze and provide a synthesis of the pertinent literature, aiming to identify and prioritize focal research topics for optimizing ex situ management. The pygmy hippo is continually reported to breed well and thus long-term survival of the species, at least in captivity, is assumed, although we identify several reasons to exercise caution. Further, we demonstrate that the common perception amongst zoological institutions that the pygmy hippo is easy to manage and experiences limited health and husbandry issues is erroneous. Specific issues affecting the captive population with potential negative implications for long-term sustainability include polycystic kidney disease (PKD), a female-biased sex ratio, obesity, a high neonatal mortality rate, and failure of many breeding pairs to reproduce. We identify several research priorities to help address these concerns, and how the resulting information can be applied to improve management, health and welfare of pygmy hippos in captivity.

A captive, 31-yr-old, intact male pygmy hippopotamus presented with nonspecific signs of weight loss, inappetence, diarrhea, and lethargy. After 5 wk of diagnostic investigation and symptomatic treatment, an acute leukemic process with concurrent polycystic kidney disease was suspected. The animal's condition continued to deteriorate prompting euthanasia. Necropsy, histopathologic, and immunohistochemical examination confirmed acute T-cell lymphoblastic leukemia and polycystic kidneys. Acute T-cell lymphoblastic leukemia has not previously been documented in this species; however, polycystic kidney disease has been reported. This case report adds to the increasing number of pygmy hippopotamuses diagnosed with polycystic kidney disease and describes acute T-cell lymphoblastic leukemia, a previously unreported disease of this species.

An adult female captive pygmy hippopotamus (Choeropsis liberiensis) was diagnosed with an oral anaplastic sarcoma. The tumor was surgically debulked and intralesional chemotherapy with mitomycin C (0.4 mg/cm3 of tumor) and cisplatin (1 mg/cm3 of tumor) was administered. Chemotherapeutic treatment proved difficult due to the risks of repeated anesthetics and unknown drug efficacies. Marked proliferation of the mass was observed during estrus, and chemotherapy was repeated as an experimental treatment to slow tumor progression in order for the animal to remain in the species breeding program. Tumor proliferation was detected during the first trimester of pregnancy; however, in the lactation period, the mass became quiescent. No adverse reactions to chemotherapeutic drugs were observed and the animal continues to be monitored for tumor progression. This is the first report of an anaplastic sarcoma and of chemotherapy use in a pygmy hippopotamus and it highlights logistical considerations for treating neoplasia in this species.

A one-month-old, female, mother-reared pygmy hippopotamus, Choeropsis liberiensis, died under anaesthesia after presenting with acute-onset regurgitation of milk. Abdominal radiographs revealed a radiodense mass within the stomach, which on postmortem examination was found to be a large, solid, stratified lactophytobezoar causing pyloric outlet obstruction. Lactobezoars are gastric concretions formed from solidified, undigested milk, sometimes mixed with mucus. When mixed with plant material, they are referred to as lactophytobezoars. Histopathology revealed aspiration pneumonia and erosive and suppurative tracheitis. Lactobezoars are diagnosed most commonly in premature human infants and have been reported occasionally in hand-reared felids and ursids. To the authors’ knowledge, this is the first report of a lactophytobezoar in a non-human mammal reared on its mother. Lactobezoars and lactophytobezoars should be considered in the list of differential diagnoses for emesis, regurgitation or abdominal mass in any milk-fed mammal, whether hand or parent-reared.

Von Economo neurons (VENs) are specialized projection neurons with a characteristic spindle-shaped soma and thick basal and apical dendrites. VENs have been described in restricted cortical regions, with their most frequent appearance in layers III and V of the anterior cingulate cortex, anterior insula, and frontopolar cortex of humans, great apes, macaque monkeys, elephants, and some cetaceans. Recently, a ubiquitous distribution of VENs was reported in various cortical areas in the pygmy hippopotamus, one of the closest living relatives of cetaceans. That finding suggested that VENs might not be unique to only a few species that possess enlarged brains. In the present analysis, we assessed the phylogenetic distribution of VENs within species representative of the superordinal clade that includes cetartiodactyls and perissodactyls, as well as afrotherians. In addition, the distribution of fork cells that are often found in close proximity to VENs was also assessed. Nissl-stained sections from the frontal pole, anterior cingulate cortex, anterior insula, and occipital pole of bowhead whale, cow, sheep, deer, horse, pig, rock hyrax, and human were examined using stereologic methods to quantify VENs and fork cells within layer V of all four cortical regions. VENs and fork cells were found in each of the species examined here with species-specific differences in distributions and densities. The present results demonstrated that VENs and fork cells were not restricted to highly encephalized or socially complex species, and their repeated emergence among distantly related species seems to represent convergent evolution of specialized pyramidal neurons. The widespread phylogenetic presence of VENs and fork cells indicates that these neuron morphologies readily emerged in response to selective forces,whose variety and nature are yet to be identified.

The pygmy hippo is an Endangered mammal endemic to West Africa, of which only 2,000–3,000 are left in the wild. Until now genetic resources to conduct monitoring of wild populations and to facilitate captive breeding have been lacking. In this study we used restriction-site associated DNA sequencing of five pygmy hippo samples to generate 1,619 high confidence candidate single nucleotide polymorphisms (SNPs) suitable for population genetic analysis. A subset of 10 of SNPs generated were validated via resequencing with 100 % success rate and through the use of KASPar DNA probes (Kbiosciences) with 90 % success rate. To facilitate future research we present the list of 1,619 SNPs ranked according to mean genotype confidence and mean coverage.

The pygmy hippopotamusChoeropsis liberiensisis an Endangered species found only in the Upper Guinea rainforests of West Africa. Using a two-phase approach, with initial semi-structured interviews followed by more extensive questionnaires, we examined local residents' awareness of and attitudes towards the pygmy hippopotamus along the Moa River near Tiwai Island Wildlife Sanctuary in Sierra Leone. The interviews and questionnaires addressed human–hippopotamus interactions, local knowledge and awareness of pygmy hippopotamus ecology and behaviour, and public attitudes towards hippopotamus conservation. Overall, 22% of questionnaire respondents acknowledged benefits related to hippopotamus conservation; factors affecting the perception of benefits included age, livestock ownership, distance from Tiwai Island and exposure to conservation programmes. The results of this study could be used to inform the conservation of the pygmy hippopotamus and highlight the critical role of local support in the management of threatened species in biodiversity hotspots.

The structure of the hippopotamus brain is virtually unknown because few studies have examined more than its external morphology. In view of their semiaquatic lifestyle and phylogenetic relatedness to cetaceans, the brain of hippopotamuses represents a unique opportunity for better understanding the selective pressures that have shaped the organization of the brain during the evolutionary process of adaptation to an aquatic environment. Here we examined the histology of the cerebral cortex of the pygmy hippopotamus (Hexaprotodon liberiensis) by means of Nissl, Golgi, and calretinin (CR) immunostaining, and provide a magnetic resonance imaging (MRI) structural and volumetric dataset of the anatomy of its brain. We calculated the corpus callosum area/brain mass ratio (CCA/BM), the gyrencephalic index (GI), the cerebellar quotient (CQ), and the cerebellar index (CI). Results indicate that the cortex of H. liberiensis shares one feature exclusively with cetaceans (the lack of layer IV across the entire cerebral cortex), other features exclusively with artiodactyls (e.g., the morphologiy of CR-immunoreactive multipolar neurons in deep cortical layers, gyrencephalic index values, hippocampus and cerebellum volumetrics), and others with at least some species of cetartiodactyls (e.g., the presence of a thick layer I, the pattern of distribution of CR-immunoreactive neurons, the presence of von Economo neurons, clustering of layer II in the occipital cortex). The present study thus provides a comprehensive dataset of the neuroanatomy of H. liberiensis that sets the ground for future comparative studies including the larger Hippopotamus amphibius.

The Pygmy Hippopotamus (PH) Choeropsis liberiensis (Morton, 1849) is a rare and cryptic mammal. Considered as an endangered species by International Union for Conservation of Nature in 2017, the main threats to PH are the fragmentation of its habitat, the forest, and hunting. Its population has greatly diminished during the last two decades from nearly 15,000 individuals to an estimated number of approximately 3,000 individuals today. Studies of this species’ ecology in the wild are rare. This study focuses on habitat use and locomotion pattern in the Tai National Park (TNP) in Cote d’Ivoire, the last stronghold of the PH in the world. Camera-traps pictures and direct observations of hippo signs and individuals were used for this study in a preselected area where observation had shown that this is the habitat of the species. The study describes the features of the micro-habitat of the PH and shows how this habitat is used daily as well as the movement pattern in the wild. These results add to the ecological knowledge of this endemic species and contribute in building a knowledge-based conservation strategy. © 2018 International Formulae Group. All rights reserved Keywords: Pygmy hippopotamus, home range, habitat requirements, West Africa