Murina yushuensis: A new species of Tube-nosed Bat from a high altitude cave on the Tibetan Plateau.

Tube-nosed Bats, Murina spp., are a large group of Vespertilionid Bats found from northeastern Russia to Papua New Guinea. There are currently 40 described species in the genus about half of which have been described in the past decade, largely from genetic studies which have uncovered many cryptic species, predominantly in South and Southeast China. These Bats are insectivorous, and generally found in lowland forests, with the maximum known diversity in South China and Southeast Asia, although this may be due to a lack of sampling in more northerly parts of China.

In a paper published in the Journal of Mammalogy on 23 October 2024, Xiaoyun Wang of the Key Laboratory of Conservation and Application in Biodiversity of South China at Guangzhou University, Xuesong Han of the Shan Shui Conservation Center and the Center for Nature and Society at Peking University, Gábor Csorba of the Department of Zoology at the Hungarian Natural History Museum, Yi Wu, also of the Key Laboratory of Conservation and Application in Biodiversity of South China at Guangzhou University, Huaiqing Chen also of the Center for Nature and Society at Peking University, Xiang Zhao and  Zhengyi Dong, also of the Shan Shui Conservation Center, Wenhua Yu,again of the Key Laboratory of Conservation and Application in Biodiversity of South China at Guangzhou University, and Zhi Lu, again of the Center for Nature and Society at Peking University, describe a new species of Murina from a high altitude cave on the Tibetan Plateau in Qinghai Province in Northeast China.

On 15 March 2018, a Bat roosting in the entrance to a cave on the bank of the Batang River about 8 km from the city of Yushu and 3770 m above sealevel was disturbed, responding by making a long, high-pitched noise. At the time the significance of this was not realised, but when the significance was realised, several repeat visits were made, with the Bat being found again on 25 December 2018.

The new species is described from this single male specimen, and is named Murina yushuensis, where 'yushuensis' means 'from Yushu'. The single specimen is 30.44 mm long (small for a member of the genus). with dark skin and small round ears, lacking the notch seen in some members of the genus. The fur of the dorsal surface is about 10 mm in length, with the basal 7 mm being black in colour, and the 3 mm at the tip being a golden brown. The fur of the ventral surface is slightly shorter, which the basal black portion being about 6 mm, and the 3 mm of the tip being pale. 

Holotype specimen of Murina yushuensis, GZHU 20077. Wang et al. (2024).

The Batang River is a tributary of the Yangtze running across the Tibetan Plateau, at altitudes of between 3860 m and 3530 m above sealevel. The area where Murina yushuensis was discovered has a mean annual temperature of only 2.9°C, and an annual average precipitation of 487 mm. The vegetation is largely meadows of Feathergrass with scattered shrubs and patches of Juniper woodland. This is a distinctly unusual environment for a member of a genus usually found in lowland tropical and subtropical forests. Murina yushuensis was discovered at the highest altitude any member of the genus has ever been recorded at, with the previous record being a specimen of the Little Tube-nosed But, Murina aurata, found at 2500 m. However, Wang et al. consider that while Murina yushuensis may seem exceptional, it is also potentially an indicator that other species of the genus may be living at high and intermediate altitudes, and not yet discovered due to a lack of sampling.

Surrounding environment of the cave where Murina yushuensis was discovered in March 2018. Wang et al. (2024).

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Myotis nustrale: A new species of Mouse-eared Bat from Corsica.

During the past three decades, the application of genetic methodologies to taxonomy has revolutionised our understanding of the world's biodiversity, with many widespread 'species' now recognised as groups of closely related, but nevertheless distinct, cryptic species, with much more restricted distributions. This in turn has implications for the ecology and conservation of these species, with species thought to be widespread and environmentally tolerant turning out to be groups of species, each of which has a limited distribution and a narrow ecological range.

One group for which this has been found to be true are Mouse-eared Bats, Myotis spp., which were once thought to be a single species, ranging from Western Europe and North Africa through the Middle East and Central Asia as far east as Korea and Japan, but which have now been shown to be a series of morphologically similar species with more limited populations.

In a paper published in the journal Revue suisse de Zoologie on 18 October 2023, Sébastien Puechmaille of the University of Montpellier, the Institut Universitaire de France, the Groupe Chiroptères de Midi-Pyrénées, and the Zoological Institute and Museum at the University of Greifswald, Serena Dool, also of the Groupe Chiroptères de Midi-Pyrénées, and the Zoological Institute and Museum at the University of Greifswald, Gregory Beuneux of the Groupe Chiroptères Corse, and Manuel Ruedi of the Muséum d’histoire naturelle de Genève, describe a new species of Mouse-eared Bat from Corsica.

The new species is named Myotis nustrale, where 'nustrale' means 'ours' in the Corsican language. It is described largely on the basis of inspection of living specimens, and comparison of genetic material taken from tissue samples to that of Mouse-eared Bats from other populations. The designated holotype is a female specimen found dead by Julien Barataud in July 2006 and preserved in alcohol, although this is noted to be in a poor state. Physically, all examined specimens of Myotis nustrale were identical to examined specimens of Myotis nattereri and Myotis crypticus in that a small black spot on the lower lip was retained into adulthood, while it was present only in juvenile members of the other species.

External characters of Myotis nustrale. Panels are close-ups of the female holotype (MNHN-ZM-2023-12), except the lower right one which is a picture from a released adult individual. The upper left panel illustrates the stiff hairs running along the uropatagium, viewed from below. The upper right panel is the right foot with wing insertion to the base of the outer toe, in ventral view. The lower left panel illustrates the long and straight tragus and unnotched ear of the female holotype. On the portrait of the live individual, notice the black chin spot on the lower lip. Puechmaille et al. (2023).

Despite its morphological similarity to other species, Myotis nustrale is clearly genetically distinct, forming a sister taxon to a clade which includes Myotis escalerai, Myotis zenatius, Myotis schaubi, Myotis tchulliensis, Myotis nattereri, Myotis hoveli, and Myotis crypticus. Myotis nustralei shows signs of long genetic isolation from other species, which at first sight might be connected to its island endemic status, although this is actually difficult to relate to our current understanding of the behaviour of Bats of the genus Myotis. Corsica, with its own species of Myotis is 50 km from the island of Elba, which in turn is 10 km from the Italian mainland. Ireland is 78 km from the island of Great Britain, which is in turn 33 km from the European mainland, but specimens of Myotis nattereri from Ireland, Great Britain, and Europe show little genetic differentiation. Similarly, Myotis hoveli is found on the Anatolian Peninsula and the island of Cyprus, separated by 69 km, and Myotis escalerai is found on the Iberian Peninsula, and the islands of Ibiza, 86 km from the mainland, Mallorca, 81 km from Ibiza, and Menorca, 36 km from Mallorca.

Bayesian topology based on five partitioned nuclear introns (SLC38A7, ABHD11, ACOX2, COPS7A and ROGDI). The outgroup (Pipistrellus pipistrellus) is not shown. Bayesian posterior probabilities (BPP) lower than 60 are not shown, neither are within species BPP values. The holotype of Myotis nustrale (sample number MNA008_CO_ALB) is indicated by a white arrow. Puechmaille et al. (2023).

Several female Myotis nustrale were equipped with radio transmitters, and tracked during spring and summer. They spent most of their time in mountainous regions more than 500 m above sealevel, although they did occasionally come close to sea level. Hunting was carried out within 8 km of the Bat's roosts, in dense maquis scrubland with stands of Evergreen Oak, Quercus ilex, and Ash, Fraxinus spp., or open forests with Corsican Pines, Pinus nigra, surrounded by Ferns.

Portraits and hind feet (dorsal view) of an adult female Myotis nustrale caught near Bavella, in southern Corsica (left) and an adult female Myotis crypticus from the Jura mountains in Switzerland (right). Notice that the latter individual has a faint line bordering the lower lip, while the former has a much more conspicuous chin spot. Wing insertion to the outer toe is, however, identical in both species. For the left individual, the wing was not stretched while it was stretched for the right individual. Puechmaille et al. (2023).

Myotis nustrale is restricted to the island of Corsica, and apparently to a small region within the Parc Naturel Régional de Corse, largely at altitudes of between 500 m and 2000 m above sealevel. The limited distribution and small population of the species would seem to make it particularly vulnerable to climate change, as the only response the Bats would have to a warming climate, would be to move upwards, leading to increased population fragmentation. 

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Nyctalus noctula: The discovery of a mass-wintering site used by the Common Noctule Bat in a town in southeast Poland.

The Common Noctule Bat, Nyctalus noctula, (Vespertilionidae) is amongst the Bat species with the longest seasonal migrations at distances as far as 1600 km. Particularly, long passages have been noted in Eastern Europe, which is characterised by longer and relatively cooler winters. Several decades ago, this Bat species was considered a regularly migrating species in Poland, particularly in the eastern part of the country. According to Petr Petrovič Strelkov the species selects areas of mean air temperature in January above –3°C for its wintering grounds. Large winter roosts have been known in Germany, where over 10 000 of hibernating Common Noctules have been found in some places.

In recent years, the number of winter records of the Common Noctule has markedly increased in Poland. Wintering of this species was noted in the central and eastern parts of the country. Increasing colonisation of urban areas and markedly enhanced sedentariness of this species was described for some places in Central Europe. Having this in mind, one may expect to find a greater number of winter roosts of the Common Noctule in Poland.

In a paper published in the journal Acta Zoologica Bulgaria on Grzegorz Lesiński and Krzysztof Janus of the Institute of Animal Sciences at the Warsaw University of Life Sciences, present the results of a study carried out in Nowy Sącz, a town in southeast Poland (83 000 inhabitants), in which a new mass-wintering site used by the Common Noctule Bats was discovered.

The study was carried out in two residential buildings built of concrete slabs. The five-storey buildings have been insulated with Styrofoam. Between the highest floors and the flat roofs of the buildings, there are low attics (with maximum height of 80 cm). Their floor has been insulated with mineral wool.

 

Building with the common noctule flying out of the attic. Arrows indicate some outlets from the attic. Lesiński & Janus (2020).

Nowy Sącz is situated in the flat bottom of the Sądecka Valley between the Dunajec River and its tributary the Kamienica Nawojowska River at an elevation from 272 to 475 m above sealevel (Majdan Hill). The town is located at the foothill of mountain ridges: Beskid Sądecki to the south, Beskid Wyspowy to the west, Beskid Niski to the east and Pogórze Rożnowskie to the north. At a short distance from the town, is the Rożnowskie Lake. The surface area of the town is 58 km² and the geographic coordinates of the housing estate are 49°37′30″ N, 20°41′44″ E.

A detailed survey of the buildings was made on 23 April, 20 July and 20 November 2014. All walls were observed with particular attention paid to cracks and openings in the walls (especially those with visible smudges of dirt and fat left by rubbing Animals), air holes and surroundings of window sills, gutters and drainpipes. Much attention was paid to the edges of metal sheets on roofs (frequent places of hiding). Marks of the presence of Bats (faeces) were searched for near the buildings. Attics were also surveyed.

Evening counting of bats flying out of attics was done on 17 September 2014. Observation of Bats leaving their daily shelter started two hours before dusk. Every flying individual was recorded and the time of start and end of Bats’ flying out of the attic was noted. Bats were identified considering their size and silhouette. Additional monitoring was performed with ultrasonic detector LunaBat DFD-1 operating in the system of frequency division. Sounds were recorded with digital sound recorder Samson Zoom H1.

Detailed survey of whole attics was made in only two buildings (Building 1 and Building 2). In other two buildings, parts of attics were surveyed on 10 February 2015. In many other buildings, studies were not possible due to unavailability of attics, which entrances were bricked up.

Counting Bats flying out of attics of two buildings just before hibernation (on 17 September 2014) revealed the presence of 546 individual Common Noctules. No other Bat species were recorded. The flight of Common Noctules took place early before dusk. The time of flying out of the attic of the Building 1 was determined for 252 individuals. The first individual flew out 50 minutes before sunset and the last one 10 minutes before sunset. The greatest intensity of flying was noted from 47 to 32 minutes before sunset. 

 

The number of Common Noctules flying out of attic in relation to the time (in minutes) before sunset (252). Lesiński & Janus (2020).

In total, 905 wintering individual Common Noctules were recorded during the survey of attics on 20 November 2014. Bats stayed on the walls of attics and on mineral wool lining the floor. Those on walls formed groups of up to 30 individuals. Moreover, surveys made on 10 February 2015 in two other buildings revealed the presence of about 230 hibernating individuals. Roosts in attics were also inhabited by Common Noctules during the reproduction period. Their number was, however, notably lower. In a single building no more than 50 individuals were present.

 

Individuals of the Common Noctule hibernating on mineral wool in building’s attic. Lesiński & Janus (2020).

Having in mind that detailed studies covered only two buildings out of 65 similar buildings in this housing estate in Nowy Sącz, Lesiński and Janus expect that several times more bats than actually observed are wintering there. During observations in September, Bats flying out of attics were noted not only from the two analysed buildings but also from several others in the neighbourhood. If other buildings were occupied by similar number of Bats, then their total number in the housing estate might be estimated at several thousand. Wintering of this species in similar buildings has also been noted in the town of Prešov (Slovakia), situated 80 km south of Nowy Sącz. So far, the nearest finding of wintering Common Noctules recorded was in Krynica (about 30 km south-east of Nowy Sącz), where one individual survived the winter of 2005/2006 in the attic of an Orthodox church. Lesiński and Janus do not exclude the possibility of other winter roosts of the common noctule in buildings in the regions of southern Poland and north-eastern Slovakia.

 

A cluster of the Common Noctule hibernating in an attic. Lesiński & Janus (2020).

Since the number of Bats occupying buildings in Nowy Sącz during reproduction is much lower than those wintering there, Lesiński and Janus expect that most wintering bats fly in from other areas. However, there are no data on the distances of their flights. An indication of how long such flights might be an example of a Common Noctule ringed in a winter roost in Slovakia and found next summer in the Białowieża Forest, north-eastern Poland. It is thus possible that buildings in Nowy Sącz serve as a winter roost for Bats inhabiting regions several hundred kilometers away. These might be the areas of eastern Poland but also in the Baltic republics and Belarus.

The described case of mass wintering of Common Noctules is certainly not exceptional and further studies should allow for finding other large winter roosts of Nyctalus noctula in Poland. Such findings may be expected also in cooler regions of the country, especially if global climate change will proceed. The threshold mean temperature in January (–3°C) that enables wintering of the Common Noctule has been recently confirmed in central and partly in eastern regions of Poland. Recently Common Noctules succesfully hibernated even in poorly isolated place (balcony) in Warsaw, central Poland.

The increasing number of winter roosts of the Common Noctule found in Central Europe confirms the deeper penetration of its populations into towns in search for shelters in buildings. With increasing trend of global climate change, these Bats could show enhanced sedentariness and likely hibernate in areas, from where they flew for wintering over 1000 km away several decades ago.

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Understanding the relationships of African Leaf-nosed Bats.

The Old World Leaf-nosed Bats, family Hipposideridae, currently include seven genera and 90 species of insectivorous Bats distributed over much of the Palaeotropics. Both the taxonomic and phylogenetic histories of this family are confused. Throughout much of its history, Hipposideridae was considered either a subfamily of the Rhinolophidae (the Horseshoe Bats) or as its sister family within the Rhinolophoidea. Recently, however, the 'Trident Bats' (Cloeotis, Paratriaenops, Rhinonicteris, and Triaenops) were shown to comprise a family-ranked group, the Rhinonycteridae, which is separate from and sister to the Hipposideridae. Even the genus Hipposideros, as it was traditionally understood, appears paraphyletic with respect to the allied genera Asellia, Aselliscus, Coelops, and Anthops. Re-validation of Macronycteris and Doryrhina for groups of Afrotropical endemic species more closely related to each other than to African and Asian members of Hipposideros sensu stricto resolved a number of those issues.

The species richness of Doryrhina, Macronycteris, and Hipposideros differs widely. Most authors recognise two species of Doryrhina (Doryrhina cyclops and Doryrhina camerunensis), five species of Macronycteris (Macronycteris commersoni, Macronycteris cryptovalorona, Macronycteris gigas, Macronycteris thomensis, and Macronycteris vittata), and 83 species of Hipposideros, 10 of which occur in Africa. These are Hipposideros beatus, Hipposideros caffer, Hipposideros curtus, Hipposideros fuliginosus, Hipposideros lamottei, Hipposideros ruber, and Hipposideros tephrus in the bicolor group of Hipposideros; Hipposideros jonesi and Hipposideros marisae in the speoris group, and Hipposideros megalotis in the megalotis group. In addition, three extinct species of Hipposiderid are known from the region: Macronycteris besaoka, from Madagascar, Hipposideros amenhotepos, from Egypt, and Hipposideros kaumbului, from Ethiopia.

As suggested by their checkered taxonomic history, phylogenetic understanding of the Hipposideridae has slowly come into focus. Doryrhina and Macronycteris are two of a dozen generic-group names that were synonymized with Hipposideros for all of the 20th century. Instead of subgenera, taxonomists used the species groups based on morphology. Assessment of Rhinolophoid relationships using an intron supermatrix based on morphology confirmed the early divergence of Hipposiderids and Rhinolophids (estimated at 41 million years ago), thereby substantiating their rank as a separate families. Despite earlier suppositions that the area of origin for Hipposideridae was in Asia or Australia. Recent studies have clearly demonstrated the ancestry of the family (and superfamily) was in Africa. A recent supermatrix analysis with the most comprehensive taxonomic sampling (42 species) confirmed the early divergence of Hipposiderids and Rhinolophids at 41.3 million years ago, but this analysis questioned the validity of both Doryrhina and Macronycteris. This study attributed the paraphyly of Hipposideros sensu lato to limited taxonomic sampling, and also challenged the integrity of the commersoni, cyclops, speoris, and bicolor species groups, arguing that all African species save for Hipposideros jonesi belonged in a single, exclusively African species group.

Although new species of Hipposiderids are regularly discovered and described in Asia, the pace of discovery has been much slower in Africa. Only one extant species has been described since the recognition of Hipposideros lamottei in 1985, and that one, Hipposideros cryptovalorona, was from Madagascar. Surveys of mitochondrial sequences from African Hipposiderids have strongly suggested that supposedly widespread species such as Hipposideros caffer and Hipposideros ruber actually represent complexes of cryptic species. Phylogenetic analyses show that these named species complexes are not monophyletic, resolving clades comprised of Bats identified as both Hipposideros caffer and Hipposideros ruber. These studies have characterised the clades in both morphological and genetic terms, even establishing them in sympatry. However, the uncertain relationship of the identified clades to the many names already proposed for Afrotropical Hipposiderids, many based on incomplete or formalin-preserved specimens, has precluded formally naming them. Incomplete geographic sampling and the lack of evidence from nuclear genes for these populations has also clouded interpretations of this mitochondrial diversity.

In a paper published in the journal ZooKeys on 22 April 2020, Bruce Patterson of the Negaunee Integrative Research Center at the Field Museum of Natural History, Paul Webala of the Department of Forestry and Wildlife Management at Maasai Mara University, Tyrone Lavery, again of the Negaunee Integrative Research Center at the Field Museum of Natural History, and the Threatened Species Recovery Hub at the Australian National University, Bernard Agwanda of the Mammalogy Section at the National Museums of Kenya, Steven Goodman, again of the Negaunee Integrative Research Center at the Field Museum of Natural History, and of the Association Vahatra, Julian Kerbis Peterhans, again of the Negaunee Integrative Research Center at the Field Museum of Natural History, and of the College of Arts and Sciences at Roosevelt University, and Terrence Demos, once again of the Negaunee Integrative Research Center at the Field Museum of Natural History, present the results of a study which used field surveys in Eastern Africa and adjoining regions to offer a new basis for considering the taxonomy and phylogenetics of Afrotropical Hipposiderids.

 

Type localities for Afrotropical Hipposiderids: Doryrhina, blue symbols; Hipposideros, white symbols; Macronycteris, black symbols. Stars denote valid species, whereas circles indicate taxa considered as subspecies or synonyms. Taxa depicted are: Hipposideros abae; Hipposideros (Pseudorhinolophus) amenhotepos; Phyllorhina angolensis; Hipposideros caffer var. aurantiaca; Hipposideros beatus; Hipposideros besaoka; Phyllorrhina bicornis; Hipposideros braima; Hipposideros caffer; Phyllorhina caffra; Hipposideros camerunensis; Hipposideros caffer centralis; Rhinolophus Commersonii; Hipposideros cryptovalorona; Hipposideros curtus; Phyllorrhina cyclops; Hipposideros gigas gambiensis; Rhinolophus gigas; Phyllorrhina gracilis; Hipposideros caffer guineensis; Hipposideros jonesi; Hipposideros kaumbului; Hipposideros lamottei; Hipposideros langi; Hipposideros marisae; Phyllorhina Commersoni, var. marungensis; Hipposideros beatus maximus; Phyllorrhina megalotis; Rhinolophus micaceus; Hipposideros Commersoni mostellum; Hipposideros nanus; Hipposideros gigas niangarae; Hipposideros caffer niapu; Phyllorrhina rubra; Hipposideros sandersoni; Hipposideros tephrus; Phyllorhina Commersoni, var. thomensis; Hipposideros gigas viegasi; Phyllorhina vittata. Patterson et al. (2020).

Patterson et al. sought to answer these questions: (1) Is there compelling evidence to support the recognition of Doryrhina and Macronycteris as distinct Afrotropical genera alongside the Palaeotropical Hipposideros? (2) Which species belong to these groups? (3) Are the traditional species groups of African Hipposiderids monophyletic? Using both mitochondrial and nuclear intron sequences, Patterson et al. also evaluate the question of cryptic species among African Hipposiderids and the possibility of mitochondrial-nuclear discordance.

In terms of cyt-b sequence divergence, clades within Doryrhina are separated by 3.0–5.7% genetic distances, whereas less than 3% separates the four recognised species of Macronycteris. Between Afrotropical Hipposideros, the greatest distances separate Hipposideros jonesi from other lineages (13.4–16.1%). The various numbered clades allied to Hipposideros caffer differ from one another in cyt-b sequences by 2.5–10.3% and clades allied to Hipposideros ruber differ by 3.0–8.2%.

The three Afrotropical Hipposiderid genera differ substantially in terms of their internal genetic differentiation. Clades of Hipposideros are separated by cyt-b p-distances averaging 9.7% (2.5–16.1%), whereas Doryrhina clades average p-distances of 4.8% (3.0–5.7%) and Macronycteris clades 2.7% (2.6–2.9%). Distance values for these genera tend to fall at the lower end of values obtained with similar sampling intensity for species-ranked clades in other Afrotropical Bat genera: 2.5% for Otomops, 9.3% for Miniopterus, 10% for Scotophilus and Rhinolophus, 13.5% for Myotis, and 17% for Nycteris. Fewer cyt-b substitutions on average for these Hipposiderids does not limit support for individual clades, and because distances do not approach those characteristic of substitutional saturation, the cyt-b tree recovers much of the deeper phylogenetic structure evident with nuclear intron sequences.

Both cyt-b and intron analyses securely recovered Doryrhina, Macronycteris, and Hipposideros as monophyletic. Doryrhina + Macronycteris are sister to the remaining Hipposiderids. However, only the cyt-b analysis included the Hipposiderid genera Aselliscus, Coelops, and Asellia alongside Hipposideros. That analysis recovered all four genera as monophyletic with strong support. Aselliscus and Coelops were recovered as sister to Hipposideros, with Asellia joining later, but these relationships lacked confident support.

 

Phylogeny of Hipposideridae based on Bayesian analysis of 303 cyt-b sequences. Colored lines denote well supported clades and symbols denote nodal support: red circles, BS at least 70%, PP at least 0.95; black circles BS at least 70%, PP no more than 0.95; open circles BS no more than 70%, PP at least 0.95. Patterson et al. (2020).

Using a supermatrix approach on exemplars of 46 species of hipposiderids, a previous study led by Lucila Inés Amador found Hipposideros sensu stricto to be paraphyletic. They recovered a mostly Asian group of Hipposideros as sister to two subclades, Coelops + Aselliscus and Asellia + African Hipposiderids excluding Hipposideros jonesi, which was recovered with the Asian taxa. Paraphyly in this molecular analysis echoed earlier indications of Hipposideros paraphyly from morphology. In another supermatrix analysis of exemplars belonging to 49 hipposiderid species, Jeff Shi and Daniel Rabosky failed to recover Macronycteris as monophyletic; Macronycteris commersoni was sister to all remaining Hipposiderids, but strangely it did not group with Macronycteris gigas. When the anomalous position of Macronycteris commersoni in their tree is ignored, their topology is highly similar to that of Patterson et al., except that Asellia (Aselliscus, Coelops) become the sister of Hipposideros (Macronycteris, Doryrhina), rather than sister of just Hipposideros. Using both mitochondrial and nuclear loci, a previous study by Tyrone Lavery, Luke Leung, and Jennifer Seddon found that 17 species of Asian, Oceanian and Australasian Hipposideros were monophyletic with respect to the genera Aselliscus, Coelops, and Anthops. Clearly, missing data and missing taxa compromise all of these phylogenetic appraisals, so that the question of Hipposiderid and Hipposideros monophyly remains open. However, subject to its sampling limitations, there is clear support in Patterson et al.'s analyses of monophyly for Doryrhina, Macronycteris, and Hipposideros as they apply these names.

Despite employing different mitochondrial and nuclear loci and using different sets of taxa, the phylogeny recovered by Lavery, Leung and Seddon is largely congruent with that of Patterson et al. Their earliest diverging species group of Hipposideros is the calcaratus group, not represented in Patterson et al.'s tree unless Hipposideros obscurus is a member. Lavery et al.'s next diverging unit is the diadema group, which is also positioned near the base of Patterson et al.'s tree. Lavery et al.'s other two groups are paired: the galeritus group (which includes Hipposideros cervinus, indicating that this species is misclassified as a calcaratus member) joined with the bicolor/ater group. In Patterson et al.'s intron analysis, members of the larvatus and diadema groups join Hipposideros obscurus as sister to all remaining Hipposideros groups. The remainder form a trichotomy: Hipposideros coronatus, typically considered in the bicolor group; Hipposideros pygmaeus and Hipposideros cervinus, which are listed in different groups but were both considered members of the galeritus unit by George Tate; and the erstwhile bicolor group, which was subdivided into the ater subgroup (for Asian, Oceanian, and Australasian species) and the ruber subgroup (for Atrotropical ones) by Ara Monadjem.

 

Phylogeny of Hipposideridae based on Bayesian analysis of 103 concatenated nuclear intron sequences. Numbers denote posterior probabilities (BI) and bootstrap percentages (ML); red circles at more terminal nodes indicate BS at least 70%, PP at least 0.95. Patterson et al. (2020).

The ater subgroup members included in Patterson et al.'s mitochondrial analysis form a well-supported clade consisting of Hipposideros bicolor, Hipposideros cineraceus, Hipposideros pomona, Hipposideros doriae, Hipposideros ater, Hipposideros khaokhouayensis, Hipposideros rotalis, Hipposideros halophyllus, Hipposideros dyacorum, Hipposideros ridley, and Hipposideros durgadasi. This group is sister to all analyzed members of the ruber subgroup: the various clades allied with Hipposideros beatus, Hipposideros caffer, and Hipposideros ruber, as well as individuals of the Afrotropical species Hipposideros lamottei and Hipposideros fuliginosus. Hipposideros abae, which was previously considered in the speoris group, is clearly a member of the ruber group. Outside this pairing are the Asian species Hipposideros cervinus, Hipposideros coronatus, Hipposideros coxi, Hipposideros obscurus, and Hipposideros pygmaeus. Two Afrotropical species also lie outside the ruber + ater clade: Hipposideros jonesi and Hipposideros marisae, both thought to belong to the speoris group.

Parsimony, topological position, and the strong support of branching relationships in the mitochondrial and intron trees make it clear that the Afrotropical ruber group represents a comparatively recent colonisation event from Asian ancestors–the ruber group is sister to the ater group and this pair has Asian sisters. However, although the basal dichotomy within Hipposideros includes an all Asian clade, lack of support for its sister(s) clouds the phylogenetic position of the Hipposideros jonesi-Hipposideros marisae clade–possibly sister to all sampled Hipposideros but more likely sandwiched between Asian clades. In any case, Patterson et al.'s analysis suggests that the Hipposideros jonesi-Hipposideros marisae clade resulted from an earlier African-Asian colonisation event.

The lack of agreement in the phylogenetic position of Hipposideros diadema and Hipposideros larvatus between the concatenated intron tree and the species tree deserves comment, as both analyses were based on the same genetic dataset. The position of Hipposideros diadema-Hipposideros larvatus as sister to the ruber group runs counter to both our other genetic analyses and morphological assessments. This discrepancy is likely due to the generally weaker support for deep nodes within the tree; in the absence of saturation, this is often taken as evidence of rapid evolutionary radiations. Hayley Lanier and Lacey Knowles used simulated data on deep phylogenies to show that species-tree methods do account for coalescent variance at deep nodes but that mutational variance among lineages poses the primary challenge for accurate reconstruction. In either case, vastly expanded genetic sampling via NGS techniques offers the most plausible avenues to clearer resolution.

However, the highly distinctive species Hipposideros megalotis belongs to its own species group and has not been included in any genetic analysis. Distributed in the Horn of Africa and the Arabian Peninsula, Hipposideros megalotis is the only Hipposiderid with a fold of skin joining the base of the ear pinnae. Its uniquely specialized auditory system and derived dentition (e.g., loss of anterior premolars and enlargement of outer lower incisors), led John Edwards Hill to regard it as a species that diverged early from the other groups of African Hipposideros. Including this species in future analyses would shed light on the group’s biogeography. Were there three colonizations of Africa by Asian groups of Hipposideros or could Hipposideros megalotis be sister to all Asian lineages of this genus? This information would greatly clarify ancestral geographic range inference.

The lineage delimitation analyses indicate that a number of Hipposiderid lineages are either unnamed or unidentified, and also that a number of recognized species may not be genetically and evolutionarily independent.

Previous studies had indicated that both Hipposideros caffer and Hipposideros ruber appear to be complexes of cryptic species. The two are traditionally distinguished on the basis of size and pelage colour, Hipposideros ruber being the larger and more brightly colored form, but this distinction is clouded by geographic variation in size and the presence of both reddish and gray-brown phases in both species. Our mitochondrial analyses identified four Hipposideros ruber lineages and eight Hipposideros caffer lineages in two distinct groupings among the sampled populations. Four of the caffer lineages and three of the ruber clades were identified as putative species by BPP analyses. The large number of clades in East Africa is remarkable: Kenya and Tanzania each support four of the eight clades allied with Hipposideros caffer, and all but one of the eight clades known from throughout the continent occur in one or the other East African country. This undoubtedly reflects the region’s great landscape diversity, where West and Central African rainforests reach their eastern limit, southern savannas reach their northern limits, the Sahel reaches its southern limits, and all are riven by the African Rift Valley. It also is a product of Patterson et al.'s sampling intensity.

 

Geographic distribution of voucher specimens used in the analysis. Patterson et al. (2020).

Because some cyt-b sequences were used in multiple studies of this group, it is possible to relate Patterson et al.'s clade labels to those used by earlier studies. Based on attributions made on morphological grounds by previous studies, some well-supported but unnamed clades in our analysis can be identified. For instance, caffer1 has a distributional range and includes specimens previously identified as Hipposideros tephrus, while specimens of caffer4 come from near the type locality of Hipposideros caffer, and may well represent that species. However, no samples confidently identified as Hipposideros ruber from the vicinity of its type locality have been sequenced, leaving the application of that name to clades in any of these trees purely conjectural. Applying formal names only after integrative taxonomic assessment is a responsible course as multispecies coalescent models like BPP can lead to over-splitting of species, especially when applied to geographically variable species complexes with parapatric distributions.

Doryrhina is a poorly known genus characterised morphologically by the peculiar club-shaped processes on the central and posterior nose leaves. This trait is shared by the two recognized African species, Doryrhina cyclops and Doryrhina camerunensis, which differ chiefly in size (the latter is larger, with forearm lengths more than 75 mm). Although Doryrhina cyclops is considered to be monotypic, mitochondrial sequences clearly separate West African populations in Liberia and Senegal (cyclops1) from Central African populations in Gabon and Central African Republic (cyclops2), and these are substantially separated from Doryrhina camerunensis and a specimen referred to that species from Tanzania. However, both the intron analysis and the species tree show little or no geographic structure. The BPP analyses confirm that none of the mitochondrial clades is behaving as an independent evolutionary lineage. Geographic structure in mtDNA but continent-wide admixture in the nuclear genome could result from either male-biased dispersal with female philopatry or highly structured seasonal migrations, which are known in other Hipposiderids. In any case, the genetic patterns of Doryrhina are hard to reconcile with its space-use behavior; individuals appear to have very small home ranges, on the order of a few hectares. An integrative taxonomic review of the genus Doryrhina is needed to determine the validity of Doryrhina cyclops and Doryrhina camerunensis. It would also shed light on whether six Australo-Papuan species tentatively allocated to that genus belong there or elsewhere. George Tate had earlier allocated those species to the Australasian muscinus group, convergent on but separate from his Afrotropical cyclops group, but John Edwards Hill.

Patterson et al.'s analysis included four of the five recognized species of Macronycteris, lacking only Macronycteris thomensis, which is endemic to São Tomé Island in the Gulf of Guinea. Two species, Macronycteris gigas and Macronycteris vittata, occur on the African mainland and two others,  Macronycteris commersoni and Macronycteris cryptovalorona, occur on Madagascar. Macronycteris cryptovalorona was named only in 2016, on the basis of its strong genetic divergence from Macronycteris cryptovalorona; appears as sister to all three remaining species of Macronycteris. Despite a search for diagnostic characters, a previous study led by Stephen Goodman could not distinguish it morphologically from Macronycteris commersoni. Both species are known to occur in the same caves in south central and southwestern Madagascar. On the other hand, Macronycteris vittata and Macronycteris gigas are distinguished typically on the basis of size and pelage colour. They are also known to occur together in the same cave, where they utilise echolocation calls with different peak frequencies: Macronycteris vittata at 64–70 kHz and Macronycteris gigas at 53.4–54.8 kHz. Both in Africa and on Madagascar, these pairs of taxa appear to act as distinct species, but the monophyly evident in the cyt-b sequences disappears in the nuclear intron analyses. BPP analyses fail to resolve any of the Macronycteris species, and none appear as monophyletic in the concatenated intron analyses.

Our results clearly underscore the importance of using multilocus datasets to evaluate phylogenetic and phylogeographic relationships at the genus and species level in Mammals. Use of a single genetic system may lead to widely divergent conclusions regarding species identity and distribution. David Toews and Alan Brelsford reviewed cases of mito-nuclear discordance in Animals generally. Fully 18% of the cases they reviewed had discordant patterns of mitochondrial and nuclear DNA. In most cases, such patterns are attributable to adaptive introgression of mtDNA, demographic disparities, and sex-biased asymmetries; in some cases they found evidence for hybrid zone movement or Human agency. Discordant patterns of variation between mitochondrial and nuclear DNA have been reported in at least six other families of Bats. A 2019 study led by Kanat Gürün implicated the role of sex-biased dispersal in causing such discordance, male dispersal spreading nuclear variation farther and faster than the movement of mitochondria. This may be a more general pattern in Bats. To understand the processes responsible for these discordant patterns of genome evolution, extensive genomic sampling and far fuller knowledge of natural history will be required.

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Marburg Virus detected in Egyptian Rousette Bat populations in Sierra Leone.

Marburg Virus, a close relative of the better-known Ebola Virus, is the founding member of the family Filoviridae, and is known to cause sporadic outbreaks of severe, often fatal disease in Humans. There have been 12 known Marburg Virus disease outbreaks, most recently in 2017 in Uganda. The largest Marburg Virus disease outbreak on record occurred in Uige, Angola, in 2005, with 227 deaths out of 252 known cases. This was the highest case-fatality ratio (90%) recorded for any large Filovirus outbreak, including the 2013–2016 Ebola Virus outbreak in West Africa (41%). A direct link to Marburg Virus spillover from Bats was not made during the event in Angola. Consistent with the high case-fatality ratio during the outbreak in Angola, the Marburg Virus Angola strain appears to be significantly more virulent than all other Marburg Virus strains (Musoke, Ravn, and Ozolin) in experimentally infected non-Human Primates. The Angola outbreak was the only Marburg Virus outbreak to originate outside of East Africa; all previous Marburg Virus disease outbreaks occurred in, or originated from, Uganda, Kenya, Democratic Republic of the Congo, or South Africa and Zimbabwe. Other Filoviruses circulating in Africa include the Marburgvirus, Ravn Virus, as well as five Ebolaviruses, Sudan Virus, Tai Forest Virus, Bundibugyo Virus, and the recently discovered Bombali Virus.

 

Negative stained transmission electron micrograph of a number of filamentous Marburg Virions, which had been cultured on Vero cell cultures, and purified on sucrose, rate-zonal gradients. Erskine Palmer/Russell Regnery/Centers for Disease Control and Prevention/Wikimedia Commons.

Extensive field studies in Uganda, Democratic Republic of the Congo, Kenya, South Africa, Gabon, and Zambia, as well as experimental infection studies in captive bats in the United States, have shown that the cave-dwelling Egyptian Rousette Bat, Rousettus aegyptiacus, is a primary natural reservoir of Marburg Virus. This discovery is consistent with the origins of Marburg Virus diseas outbreaks that, when known, have been linked to caves or mines, with Marburg Virus most often having spilled over to miners who work underground in known Egyptian Rousette Bat roosting sites, and occasionally to tourists who viewed Egyptian Rousette Bats too closely. Infected Egyptian Rousette Bats shed Marburg Virus in saliva and urine, and the Virus can persist for weeks in various tissues, particularly liver, spleen, and lymph nodes. Under experimental conditions, Marburg Virus can be transmitted directly between Egyptian Rousette Bats in the absence of Arthropod vectors. Furthermore, some infected Bats appear to be supershedders, capable of shedding a disproportionate amount of Virus, leading to increased Bat-Bat transmission in accordance with the Pareto principle. To date, Arthropod vectors do not appear to contribute to natural enzootic transmission of Marburg Virus among Egyptian Rousette Bats.

In equatorial Africa, Egyptian Rousette Bats live in very large, dense colonies sometimes numbering over 100 000 Bats. They can breed twice a year, producing thousands of susceptible juvenile Bats every six months in a single Egyptian Rousette Bats roost. Field studies in Uganda showed that 2–3% of all Egyptian Rousette Bats are actively infected with Marburgviruses (Marburg Virus and Ravn Virus) at any one time and that infection levels spike biannually, up to 12% on average, in juvenile Bats. Importantly, these seasonal spikes appear to be associated with increased risk of Human exposure, as they coincide with over 84% of known Marburg Virus spillover events to Humans. Despite the linkage of Egyptian Rousette Bats to Human Marburg Virus outbreaks, attempts to mitigate risk through Bat extermination were counterproductive and led to increased levels of active Marburg Virus infection in the recolonising Bat population.

 

A colony of Egyptian Rousette Bats, Rousettus aegyptiacus. Giovanni Mari/Flikr/iNaturalist.

Since 2007, over 80 distinct Marburg Virus genomic sequences and 21 Virus isolates have been obtained from tissues of infected wild-caught Egyptian Rousette Bats, representing every major Marburg Virus strain found in Marburg Virus disease outbreaks since 1967, with the exception of the Angola strain. In Gabon, South Africa and Zambia, Marburg Virus was detected in Egyptian Rousette Bats despite no known associated Human Marburg Virus disease outbreaks in the country. 

In a paper published in the journal Nature Communications on 24 January 2020, a team of scientists led by Brian Amman of the Viral Special Pathogens Branch of the Centers for Disease Control and Prevention report the presence of Marburg Virus, including an Angola-like Marburg Virus, in Egyptian Rousette Bats in Sierra Leone, West Africa.

Importantly, no Marburg Virus disease outbreaks have been reported in Sierra Leone despite the presence of Marburg Virus. Amman et al.'s findings highlight the value of engaging with all stakeholders with appropriate messaging that identify and mitigate pathogens of public health concern before recognized spillovers occur. This is in consonant with measures that ensure Animal and environmental health. Moreover, it underpins the One Health surveillance approach that recognizes the interconnected relationship between  people and other organisms (Plants and Animals) in a shared environment.

A total of 1755 Bats from 42 species were captured and sampled from 4 districts in Sierra Leone: Moyamba (Kasewe Cave), Kailahun (Tailu Village), Koinadugu (Kakoya Cave), and Kono (Koema Cave). All Bat samples were tested for 5 Filoviruses (Ebola Virus, Tai Forest Virus, Bundibugyo, Marburg Virus, and Ravn Virus). Of these, 435 Bats were identified as Egyptian Rousette Bats (186 from Kasewe Cave; 7 from Tailu Village; 131 from Kakoya Cave; and 111 from Koema Cave), from which 11 bats (2.5%) tested positive for active Marburg Virus infection by Virus-specific real-time reverse transcription polymerase chain reaction or consensus reverse transcription polymerase chain reaction. Marburg Virus-positive samples included six liver/spleen, five lymph nodes, two oral swabs, one salivary gland, and one whole blood sample. Marburg Virus isolation was attempted on all polymerase chain reaction positive tissues (13) and swabs (2), and from those, four Virus isolates were obtained from three Egyptian Rousette Bats caught at Kasewe Cave. Two Marburg Virus isolates were obtained from one Bat (no. 960), one from the liver/spleen and the other from lymph node, while one isolate was obtained from two other Bats (nos. 968 and 1000), each from liver/spleen. Owing to a non-destructive sampling protocol, tissue specimens from Egyptian Rousette Bats captured at Kakoya and Koema Caves were not available for similar analysis.

 

Map of Sierra Leone showing Bat trapping locations. Enlarged map shows locations of caves where populations of Marburg Virus-positive Egyptian Rosette Bats, Rousettus aegyptiacus, were discovered (orange circles). The numbers of Egyptian Rousette Bats captured at each site are shown below the cave name. Shown on the map of Africa are locations of Marburg Virus discovery in Egyptian Rousette Bats without an outbreak (blue circles), known Marburg Virus outbreaks (yellow circles), and the fragmented geographic range of the Marburg Virus natural reservoir, Rousettus aegyptiacus (orange shaded). Amman et al. (2020).

Marburg Virus sequences from small diagnostic NP and VP35 gene fragments were determined from 10 of the 11 polymerase chain reaction-positive bats using an array of sequencing approaches, depending on the institution performing the surveillance and sequence analysis. These Marburg Virus sequences were then compared by maximum-likelihood phylogenetic analysis to 128 NP and/or VP35 sequence fragments obtained previously from Egyptian Rousette Bats or Humans in Uganda, Democratic Republic of the Congo, Angola, Gabon, and Kenya. The phylogenetic analysis shows that the Sierra Leone-derived Marburg Virus sequences are most closely related to sequences obtained in Gabon and Angola. In addition, Marburg Virus full-length genome sequences were determined by genome walking of Marburg Virus RNA extracted from oral swabs and whole blood (2), one of which was phylogenetically similar to the Angola-like Marburg Virus isolates (4). Unexpectedly, Marburg Virus isolate sequences from Bats nos. 960 (2), 968, and 1000 were 100% identical across the full-length Virus genome. To rule out cross-contamination during Virus isolation, RNA was extracted directly from Egyptian Rousette Bats tissues and approximately 5 kb of Marburg Virus RNA was sequenced using an Angola strain-specific tiling and amplification approach. As with the Marburg Virus isolate sequences, all tissue-derived Marburg Virus sequences from those three Bats were 100% identical.

Among the 193 Egyptian Rousette Bats captured at Kasewe Cave and Tailu Village, 140 (72.5%) were juveniles (forearm length under 90 mm), and 53 (27.5%) were adults. All of the Marburg Virus polymerase chain reaction-positive Kasewe Cave Egyptian Rousette Bats (9/186) were classified as juveniles (4.8%). A total of 242 Egyptian Rousette Bats were sampled at Kakoya and Koema Caves. Of these, 87 (36%) were juveniles and 155 (64%) were adults. Like the Kasewe Cave and Tailu Village sites, all Marburg Virus polymerase chain reaction positive Egyptian Rousette Bats (2/242; 0.8%) were juveniles. A significant age bias was detected among Marburg Virus-positive Bats; all 11 polymerase chain reaction-positive Bats were juveniles. No sexual bias with respect to Marburg Virus active infection was detected between male (6) and female (5) polymerase chain reaction-positive Bats.

Marburg Virus-specific IgG antibody was detected in 24/140 (17.1%) Egyptian Rousette Bats captured at Kasewe Cave (136 serum tested) and Tailu Village (4 serum tested). Notably, two of these Marburg Virus IgG antibody-positive Bats were also positive by real-time quantitative reverse transcription polymerase chain reaction. No sexual bias was observed in Marburg Virus-specific IgG antibody-positive Egyptian Rousette Bats (5/49, or10.2%, female; 19/91, or 20.9%, male). Consistent with previous studies of wild-caught Egyptian Rousette Bats in Uganda, there was a significant age bias, as 32.4% of adults (12/37) were antibody-reactive to Marburg Virus compared to 11.7% of juveniles (12/103). Sera from Egyptian Rousette Bats captured at Kakoya and Koema Caves were not available for IgG analysis.

Amman et al. present evidence of active Marburg Virus circulation in West African Egyptian Rousette Bat based on polymerase chain reaction, antibody, and Virus isolation data and provide the first report of an Angola-like strain of Marburg Virus since it was first detected in humans in 2005. Importantly, this discovery occurred prior to any known Marburg Virus disease outbreak in Sierra Leone and was used to implement evidence-based public health messaging to at-risk communities about Marburg Virus spillover risk. To accomplish this, a comprehensive One Health communications approach leveraging the human, animal, and environmental and emergency health sectors within the Ministries of Health and Sanitation, and Agriculture and Forestry and Food Security along with other international partners was implemented across national, district, and local community levels. Through several engagement meetings with Ministry of Health and Sanitation and with several relevant ministries, departments and agencies, (Ministry of Agriculture Forestry and Food security, Ministry of Local Government, Ministry of Lands, Ministry of Mines and Mineral Resources, Environment and Protection Agency, Office of National Security) over a two-week period, briefing documents including Marburg factsheets, Marburg Virus disease preparedness, detection and response plans were developed and presented at a national conference. This resulted in recommendations for public health outreach, with a team comprised of key stakeholders (government health and agriculture units, universities, development partners and district and local authorities) across the capital city and three of the districts (Moyamba, Koinadugu and Kono). This outreach team conducted initial information sharing events in each community near the Egyptian Rousette Bat colonies followed by regular in-person meetings with traditional community leaders and other local stakeholders to provide key messages related to virus exposure risks and methods to reduce contact with Bats. Concerns raised by local communities where bushmeat consumption brings them in contact with Bats for livelihood were noted and discussed, and local perceptions about Bats were explored in developing options for minimizing exposure risks. As an additional national-level public preparedness measure, Marburg Virus disease has now been included in testing regimens at national laboratories in Sierra Leone.

Marburgviruses have been found in multiple Egyptian Rousette Bat populations across sub-Saharan and South Africa. Though fragmented, the geographic range for Egyptian Rousette Bats extends into West Africa, covering areas of Liberia, Sierra Leone, and Guinea that contain fruiting trees and caves. Therefore, finding 11 Marburg Virus positive Egyptian Rousette Bats from three separate districts (Moyamba, Koinadugu, and Kono) in Sierra Leone is not unexpected, and together with previous field studies supports the evidence that Egyptian Rousette Bats are the primary Marburg Virus natural reservoir. The finding of multiple and diverse Marburg Virus genetic lineages simultaneously circulating in geographically distinct locations in Sierra Leone suggests that Marburg Virus has been present in West Africa for an extended period of time and is not a recent introduction from other areas of Africa. Indirect fluorescent antibody data suggested that Human Marburg Virus infections may have occurred and gone unrecognised in Liberia in the late 1970s, yet due to specificity issues with the indirect immunofluorescence antibody test at that time, the significance of the findings were unclear. Nevertheless, the isolation of genetically identical viruses from 3/9 Bats caught at the same cave (Kasewe Cave) was surprising. Of note, all three infected juvenile Bats were caught at approximately the same time (within a day of each other). During similar Marburg Virus surveillance activities in Uganda from 2007–2012, 21 genetically distinct Marburgviruses, including Ravn Virus, were isolated directly from Egyptian Rousette Bats, but none were genetically identical to another. In Sierra Leone, we suspect that finding two or more Bats simultaneously infected with the same Marburg Virus lineage is a consequence of being infected from a single point source, perhaps a supershedder Egyptian Rousette Bat interacting with other Bats in a small colony. Moreover, juvenile Bats are known to roost together in caves, a behavior that may facilitate Bat-to-Bat transmission from infected to susceptible individuals. In addition, the field teams did not observe evidence of massive Egyptian Rousette Bat colonies at Kasewe, Kakoya, and Koema Caves like those seen in East Africa making multiple infections stemming from one source more likely. The determination that the Egyptian Rousette Bat colonies are comparatively small is based on the lack of widespread fecal deposits on vegetation near the colony entrances, unlike the copious amounts normally seen in East African Egyptian Rousette Bat populations. Future investigations will include mark-recapture studies to better estimate population sizes at these locations. Overall, the presence of the Egyptian Rousette Bat natural reservoir throughout portions of sub-Saharan Africa implies that Marburgviruses could be present in Bat populations in many localities with suitable habitat for this species even though no Marburg Virus disease outbreaks have yet been recorded.

The Marburg Virus infection data from the four capture sites indicates an age bias towards juvenile Egyptian Rousette Bats that is consistent with previous studies in Uganda and South Africa. Overall, more juveniles were actively infected with Marburg Virus, while more adults had antibody reactive to Marburg Virus. As with Uganda and South Africa, this is indicative of juveniles having maternal antibody for the first few months after birth, providing protection against Marburg Virus infection. That antibody eventually wanes, leaving the older (4-6 months) juvenile cohort susceptible to infection. As the Bats get older, the chances of having been infected with Marburg Virus increase, leading to the increased prevalence of Marburg Virus-specific antibody detected in the adults.

The Marburg Virus phylogeny shows that sequences obtained from Egyptian Rousette Bats in Sierra Leone align most closely with viruses previously found in Egyptian Rousette Bats in Gabon and Democratic Republic of the Congo from 2006–2009, and in Humans in Angola in 2005. The detection of an Angola-like strain is noteworthy because this is the first time it has been identified in Egyptian Rousette Bats even though all other major Marburgvirus lineages, including Ravn Virus, have been detected co-circulating in a single Egyptian Rousette Bat population in Uganda or Democratic Republic of the Congo. In that context, the overall genetic diversity detected to date in the West African Marburg Virus sequences is comparatively lower and may be a consequence of smaller colony sizes compounded by long-term immunity in previously infected bats. Experimental infection studies of captive Egyptian Rousette Bats have shown that bats retain immunity to Marburg Virus reinfection for up to two years despite diminished antibody levels, suggesting that reinfection is not a major driver of Virus persistence in the population. This type of infection dynamic in Egyptian Rousette Bats would further limit the number of susceptible Bat hosts within a colony, thereby potentially limiting the number of Virus strains that can co-circulate within an Egyptian Rousette Bat roost. The fact that the Marburg Virus strains detected in Sierra Leonean Egyptian Rousette Bats are most similar to those seen in other locations on the west coast of Africa (Gabon and Angola) may be reflective of restricted Egyptian Rousette Bat movement and consistent with isolation of Egyptian Rousette Bat populations in Sierra Leone from the larger metapopulation of Egyptian Rousette Bats across most of Central and East Africa. One reason for this isolation could be loss of contiguous habitat through degradation of forested lands that bridge the gap between the Congo Basin and West Africa.

The clear and unwavering recommendation by the Amman et al. is for individuals living and working in close proximity to caves and mines inhabited by Egyptian Rousette Bats to avoid these Bats. Extermination of a reservoir species as a means of zoonotic pathogen control has been shown to be ineffective and can result in higher ratios of active infection. In one recent example, a Ugandan gold mine was sealed and more than 100 000 Egyptian Rousette Bats destroyed. Over the course of several years, the Bats returned and the prevalence of Marburg Virus infection in the Bat population more than doubled. This recolonization was soon followed by the largest human Marburg Virus disease outbreak in Ugandan history, centered in a nearby town. These data show that culling Bat populations may lead to increased Human health risks and thus should be avoided as a pathogen control measure. Furthermore, as a frugivorous species, Egyptian Rousette Bats play an extremely important ecological role in forest regeneration by dispersing seeds and facilitating pollination of the fruiting trees they visit on a nightly basis. The ecological benefits of Bat activity are critical for the survival of the threatened environment in which they live. Tropical forests in Sierra Leone, Liberia, and Côte d’Ivoire were reported to be most at risk in terms of vulnerability, exposure, and pressure from agricultural expansion. Of those West African countries, Sierra Leone was identified as having the greatest pressure from population and income growth resulting in commodity crop expansion and foreign land investment. With reports of existing vegetative cover in the upper Guinean forests showing losses of nearly 80%, ecologically important species like Egyptian Rousette Bats are crucial to the health and longevity of this fragile ecosystem. Perhaps identifying Egyptian Rousette Bats as the source of Marburg Virus in West Africa can serve as a public deterrent and promote Bat avoidance instead of destruction.

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