Hard ticks (Acari: Ixodidae) parasitizing bushbabies (Mammalia: Galagidae) in a biodiversity hotspot of northern South Africa.

South Africa has six species of primates, three of which are bushbabies (family Galagidae). Very little information is available on their parasites due to the lack of longitudinal studies, although Rhipicephalus appendiculatus, Amblyomma hebraeum and Haemaphysalis elliptica were previously reported from the brown greater galago (Otolemur crassicaudatus) in South Africa. During 2014-2019, 83 O. crassicaudatus (70 live-trapped and 13 deceased animals) were checked for the presence of hard ticks, all from Limpopo Province, South Africa. Seventy-three of 83 (88 %) galagos were found to be tick-infested. Among ixodid genera, Haemaphysalis had the highest prevalence (46 % of the bushbabies), followed by Rhipicephalus (25 %) and Ixodes (18 %). In total, ten tick species were identified. Importantly, all infestations were monospecific. Ticks occurred on various body parts of bushbabies, thus no predilection site was noted. In conclusion, while previously only three ixodid species were known to infest bushbabies in South Africa, the present study showed that these animals can be parasitized by a much broader range of hard ticks.

Variable digestibility of captive northern greater galagos (Otolemur garnettii) fed experimental "frugivorous" and "invertebrate" diets.

Few studies have addressed the nutritional ecology of galagos. Observations of galagos in the wild reveal that they rely on fruits and invertebrates to varying degrees depending on their availability. We conducted a 6-week comparative dietary analysis of a colony of captive-housed northern greater galagos (Otolemur garnettii), which included five females and six males with known life histories. We compared two experimental diets. The first was fruit dominated and the second was invertebrate dominated. For each diet, we examined dietary intake and apparent dry matter digestibility over the course of 6 weeks. We found significant differences between the apparent digestibility of the diets, with the "invertebrate" diet being more digestible than the "frugivorous" diet. The lower apparent digestibility of the "frugivorous" diet was driven by the higher fiber contents of the fruits provided to the colony. However, variation in apparent digestibility of both diets was found among individual galagos. The experimental design used in this study may provide useful dietary data for the management of captive colonies of galagos and other strepsirrhine primates. This study may also be helpful for understanding the nutritional challenges faced by free-ranging galagos through time and across geographic space.

Overall patterns of eye-specific retino-geniculo-cortical projections to layers III, IV, and VI in primary visual cortex of the greater galago (Otolemur crassicudatus), and correlation with cytochrome oxidase blobs.

Studies in the greater galago have not provided a comprehensive description of the organization of eye-specific retino-geniculate-cortical projections to the recipient layers in V1. Here we demonstrate the overall patterns of ocular dominance domains in layers III, IV, and VI revealed following a monocular injection of the transneuronal tracer wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP). We also correlate these patterns with the array of cytochrome oxidase (CO) blobs in tangential sections through the unfolded and flattened cortex. In layer IV, we observed for the first time that eye-specific domains form an interconnected pattern of bands 200-250 µm wide arranged such that they do not show orientation bias and do not meet the V1 border at right angles, as is the case in macaques. We also observed distinct WGA-HRP labeled patches in layers III and VI. The patches in layer III, likely corresponding to patches of K lateral geniculate nucleus (LGN) input, align with layer IV ocular dominance columns (ODCs) of the same eye dominance and overlap partially with virtually all CO blobs in both hemispheres, implying that CO blobs receive K LGN input from both eyes. We further found that CO blobs straddle the border between layer IV ODCs, such that the distribution of CO staining is approximately equal over ipsilateral and contralateral ODCs. These results, together with studies showing that a high percentage of cells in CO blobs are monocular, suggest that CO blobs consist of ipsilateral and contralateral subregions that are in register with underlying layer IV ODCs of the same eye dominance. In macaques and humans, CO blobs are centered on ODCs in layer IV. Our finding that CO blobs in galago straddle the border of neighboring layer IV ODCs suggests that this novel feature may represent an alternative way by which visual information is processed by eye-specific modular architecture in mammalian V1.

Bone volume in the distal calcaneus correlates with body size but not leap frequency in galagids.

OBJECTIVES: Primate leap performance varies with body size, where performance will be optimized in lightweight individuals due to the inverse relationship between force generation and body mass. With all other factors equal, it is less energetically costly to swing a light hindlimb than a heavier hindlimb. Previous work on the calcaneus of galagids hypothesized that bone volume in leaping galagids may be minimized to decrease overall hindlimb mass. We predict that (1) lighter taxa will exhibit relatively less calcaneal bone volume than heavier taxa, and (2) taxa that are high-frequency leapers will exhibit relatively less bone volume than lower frequency leapers. MATERIALS AND METHODS: Relationships among bone volume, body size, and leap frequency (high vs. low) were examined in a sample of 51 individuals from four genera of galagids (Euoticus, Galago, Galagoides, and Otolemur) that differ in the percentage of time engaged in leaping locomotion. Using µCT scans of calcanei, we quantified relative bone volume (BV/TV) of the distal calcaneal segment and predicted that it would vary with body size and frequency of leaping locomotion. RESULTS: Phylogenetic generalized least squares (PGLS) regression models indicate that body size, but not leaping frequency, affects BV/TV in the distal calcaneus. Relative bone volume increases with body size, supporting our first hypothesis. DISCUSSION: These results support previous work demonstrating a positive correlation between BV/TV and body size. With some exceptions, small galagids tend to have less BV/TV than larger galagids. Leaping frequency does not relate to BV/TV in this sample; larger taxonomic and/or behavioral sampling may provide additional insights.

Taxonomic and geographic bias in 50 years of research on the behaviour and ecology of galagids.

Identifying knowledge gaps and taxonomic and geographic bias in the literature is invaluable for guiding research towards a more representative understanding of animal groups. Galagids are nocturnal African primates and, for many species, detailed information on their behaviour and ecology is unavailable. To identify gaps and bias in the literature we reviewed published peer-reviewed research articles on galagid behaviour and ecology over a 50-year period from January 1971 to December 2020. Using the Web of Science and Google Scholar databases, we identified 758 articles, assessed 339 full texts for eligibility and included 211 in the review. Species of Otolemur have been extensively researched in comparison to other genera (78.2% of studies; Euoticus: 13.3% of studies; Galago: 66.4% of studies; Galagoides: 20.9% of studies; Paragalago: 22.3% of studies; Sciurocheirus: 15.2% of studies). The most common category of research was physiology (55.0% of studies), followed by behavioural ecology (47.4% of studies), and fewer studies were on genetics and taxonomy (16.1% of studies) and habitat and distribution (14.2% of studies). Text mining revealed that the word 'behaviour' was the most common word used in abstracts and keywords, and few words were related to ecology. Negative binomial regression revealed that mean body mass and geographic range size were significant positive predictors of the total number of scientific outputs on each species. Research on wild populations was carried out in only 24 (60%) of the 40 countries galagids are thought to inhabit. Studies were undertaken in locations with lower mean annual temperatures and higher human population densities over warmer and less populated areas. We encourage a more equal sampling effort both taxonomically and geographically that in particular addresses the paucity of research on smaller species and those with restricted ranges. Research on in situ populations, especially in warmer and remote areas, is urgently needed, particularly in West, Central and some Southern African countries.

The distribution, number, and certain neurochemical identities of infracortical white matter neurons in the brains of a southern lesser galago, a black-capped squirrel monkey, and a crested macaque.

In the current study, we examined the number, distribution, and aspects of the neurochemical identities of infracortical white matter neurons, also termed white matter interstitial cells (WMICs), in the brains of a southern lesser galago (Galago moholi), a black-capped squirrel monkey (Saimiri boliviensis boliviensis), and a crested macaque (Macaca nigra). Staining for neuronal nuclear marker (NeuN) revealed WMICs throughout the infracortical white matter, these cells being most dense close to inner cortical border, decreasing in density with depth in the white matter. Stereological analysis of NeuN-immunopositive cells revealed estimates of approximately 1.1, 10.8, and 37.7 million WMICs within the infracortical white matter of the galago, squirrel monkey, and crested macaque, respectively. The total numbers of WMICs form a distinct negative allometric relationship with brain mass and white matter volume when examined in a larger sample of primates where similar measures have been obtained. In all three primates studied, the highest densities of WMICs were in the white matter of the frontal lobe, with the occipital lobe having the lowest. Immunostaining revealed significant subpopulations of WMICs containing neuronal nitric oxide synthase (nNOS) and calretinin, with very few WMICs containing parvalbumin, and none containing calbindin. The nNOS and calretinin immunopositive WMICs represent approximately 21% of the total WMIC population; however, variances in the proportions of these neurochemical phenotypes were noted. Our results indicate that both the squirrel monkey and crested macaque might be informative animal models for the study of WMICs in neurodegenerative and psychiatric disorders in humans.

A Comparison of the Efficacy and Cardiopulmonary Effects of 3 Different Sedation Protocols in Otolemur garnettii.

The Northern greater galago (Otolemur garnettii) is a prosimian primate most commonly used to study the evolutionary development of vision and somatosensation. This study aimed to investigate the efficacy and cardiopulmonary effects of 3 sedation protocols commonly used in other primate species: 1) alfaxalone (Alf; 8 mg/kg IM) 2) ketamine alone (Ket; 20 mg/kg IM) and 3) ketamine + dexmedetomidine (Ket+Dex; 4 mg/kg + 25 µg/kg IM) with reversal (atipamezole; 250 µg/kg IM). A total of 34 animals were evaluated, including 11 juveniles and 23 adults. Cardiopulmonary parameters such as indirect blood pressure, heart rate, respiratory rate, and SpO2 were measured, and blood was collected for blood gas analysis and a chemistry panel. To examine the efficacy of each sedation protocol, induction time, immobilization time, and recovery time were recorded. Subjective measures of quality and efficacy included quality of induction, pedal withdrawal reflex, palpebral reflex, muscle tension, rectal temperature, and quality of recovery. All 3 protocols successfully immobilized the animals and all animals recovered from sedation. Heart rates were highest among the Ket group and the lowest for the Ket+Dex group. On average, the Alf group was immobilized for twice as long as either the Ket or Ket+Dex groups. The Ket+Dex group had the fastest average recovery time and subjectively had the best quality of recovery. Based on these results, Ket+Dex is recommended over Alf or Ket alone for brief sedation of healthy galagos.

Cryptic diversity and species boundaries within the Paragalago zanzibaricus species complex.

The recently described genus Paragalago is a complex of several nocturnal and morphologically cryptic species distributed in the forests of eastern Africa. Species diversity within this genus has been mainly described using species-specific differences in their loud calls. However, molecular data are still lacking for this group and species boundaries remain unclear. In this study, we explore species diversity within the zanzibaricus-complex using a combination of mitochondrial and nuclear data and comparing multiple species delimitation methods. Our results consistently support the existence of three independent lineages, P. cocos, P. zanzibaricus, and P. granti, confirming previous hypotheses based on vocal data. We conclude that these three lineages represent valid cryptic species and we hypothesize that speciation within this complex was characterized by cycles of forest expansion and contraction in the Plio-Pleistocene.

The postnatal development of MT, V1, LGN, pulvinar and SC in prosimian galagos (Otolemur garnettii).

Considerable evidence supports the premise that the visual system of primates develops hierarchically, with primary visual cortex developing structurally and functionally first, thereby influencing the subsequent development of higher cortical areas. An apparent exception is the higher order middle temporal visual area (MT), which appears to be histologically distinct near the time of birth in marmosets. Here we used a number of histological and immunohistological markers to evaluate the maturation of cortical and subcortical components of the visual system in galagos ranging from newborns to adults. Galagos are representative of the large strepsirrhine branch of primate evolution, and studies of these primates help identify brain features that are broadly similar across primate taxa. The histological results support the view that MT is functional at or near the time of birth, as is primary visual cortex. Likewise, the superior colliculus, dorsal lateral geniculate nucleus, and the posterior nucleus of the pulvinar are well-developed by birth. Thus, these subcortical structures likely provide visual information directly or indirectly to cortex in newborn galagos. We conclude that MT resembles a primary sensory area by developing early, and that the early development of MT may influence the subsequent development of dorsal stream visual areas.

Calcaneal elongation and bone strength in leaping galagids.

OBJECTIVES: Small-bodied vertical clinging and leaping primates have elongated calcanei which enhance leap performance by optimizing leap velocity, distance, and acceleration, but at the expense of experiencing relatively large forces during takeoff and landing. This study tests the hypothesis that the elongated calcaneus of leaping galagids is adapted to resist larger and more stereotyped bending loads compared to more quadrupedal galagids. MATERIALS AND METHODS: The calcanei of 14 individuals of Otolemur and 14 individuals of Galago (three species of each genus) were µCT scanned. Calcaneal cross-sectional properties (maximum and minimum second moments of area and polar section modulus) were obtained from a slice representing the 50% position of bone segment length and dimensionless ratios were created for each variable using calcaneal cuboid facet area as a proxy for body mass. RESULTS: There were no significant differences in size-adjusted bending strength between Galago and Otolemur. Galago exhibited more elliptically shaped calcaneal cross sections, however, suggesting that its calcanei are more adapted to stereotyped loading regimes than those of Otolemur. DISCUSSION: The results suggest that the calcaneus of specialized leapers is adapted to more stereotyped loading patterns. The lack of predicted bone strength differences between Galago and Otolemur may be related to body size differences between these taxa, or it may indicate that loads encountered by Galago during naturalistic leaping are not reflected in the available experimental force data.

Vocal Repertoire and Intraspecific Variation within Two Loud Calls of the Small-Eared Greater Galago (Otolemur garnettii) in Tanzania and Kenya.

Vocal repertoires and call structure can provide insights into the behaviour and evolution of species, as well as aid in taxonomic classification. Nocturnal primates have large vocal repertoires. This suggests that acoustic communication plays an important role in their life histories. Little is known about the behavioural context or the intraspecific variation of their vocalisations. We used autonomous recording units and manual recorders to investigate the vocal behaviour and structure of loud calls of the small-eared greater galago (Otolemur garnettii)in Kenya and Tanzania. We describe the vocal repertoire, temporal calling patterns and structure of 2 loud calls of 2 subspecies: O. g. panganiensis and O. g. kikuyuensis. We found considerable intraspecific structural differences in both loud calls. These are congruent with the current subspecies classification. Differences in vocalisations among populations are not consistent with the "acoustic adaptation hypothesis," rather they are likely a result of geographic variation due to isolation caused by vegetational barriers in southern Kenya.

Cortical projections to the two retinotopic maps of primate pulvinar are distinct.

Comprised of at least five distinct nuclei, the pulvinar complex of primates includes two large visually driven nuclei; one in the dorsal (lateral) pulvinar and one in the ventral (inferior) pulvinar, that contain similar retinotopic representations of the contralateral visual hemifield. Both nuclei also appear to have similar connections with areas of visual cortex. Here we determined the cortical connections of these two nuclei in galagos, members of the stepsirrhine primate radiation, to see if the nuclei differed in ways that could support differences in function. Injections of different retrograde tracers in each nucleus produced similar patterns of labeled neurons, predominately in layer 6 of V1, V2, V3, MT, regions of temporal cortex, and other visual areas. More complete labeling of neurons with a modified rabies virus identified these neurons as pyramidal cells with apical dendrites extending into superficial cortical layers. Importantly, the distributions of cortical neurons projecting to each of the two nuclei were highly overlapping, but formed separate populations. Sparse populations of double-labeled neurons were found in both V1 and V2 but were very low in number (<0.1%). Finally, the labeled cortical neurons were predominately in layer 6, and layer 5 neurons were labeled only in extrastriate areas. Terminations of pulvinar projections to area 17 was largely in superficial cortical layers, especially layer 1.