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Background The recognition and delineation of morphologically indistinguishable cryptic species can have broad implications for wildlife conservation, disease ecology and accurate estimates of biodiversity. Parasites are intriguing in the study of cryptic speciation because unique evolutionary pressures and diversifying factors are generated by ecological characteristics of host-parasite relationships, including host specificity. Bat flies (Diptera: Nycteribiidae and Streblidae) are obligate, hematophagous ectoparasites of bats that generally exhibit high host specificity. One rare exception is Penicillidia fulvida (Diptera: Nycteribiidae), an African bat fly found in association with many phylogenetically distant hosts. One explanation for P. fulvida’s extreme polyxeny is that it may represent a complex of host-specific yet cryptic species, an increasingly common finding in molecular genetic studies of supposed generalist parasites. Methods A total of 65 P. fulvida specimens were collected at 14 localities across Kenya, from bat species representing six bat families. Mitochondrial cytochrome c oxidase subunit 1 (COI) and nuclear 28S ribosomal RNA (rRNA) sequences were obtained from 59 specimens and used to construct Bayesian and maximum likelihood phylogenies. Analysis of molecular variance was used to determine how genetic variation in P. fulvida was allocated among host taxa. Results The 28S rRNA sequences studied were invariant within P. fulvida. Some genetic structure was present in the COI sequence data, but this could be more parsimoniously explained by geography than host family. Conclusions Our results support the status of P. fulvida as a rare example of a single bat fly species with primary host associations spanning multiple bat families. Gene flow among P. fulvida utilizing different host species may be promoted by polyspecific roosting behavior in bats, and host preference may also be malleable based on bat assemblages occupying shared roosts. The proclivity of generalist parasites to switch hosts makes them more likely to vector or opportunistically transmit pathogens across host species boundaries. Consequently, the presence of polyxenous bat flies is an important consideration to disease ecology as bat flies become increasingly known to be associated with bat pathogens. Graphical Abstract

Skin is the largest mammalian organ and the first defensive barrier against the external environment. The skin and fur of mammals can host a wide variety of ectoparasites, many of which are phylogenetically diverse, specialized, and specifically adapted to their hosts. Among hematophagous dipteran parasites, volatile organic compounds (VOCs) are known to serve as important attractants, leading parasites to compatible sources of blood meals. VOCs have been hypothesized to be mediated by host-associated bacteria, which may thereby indirectly influence parasitism. Host-associated bacteria may also influence parasitism directly, as has been observed in interactions between animal gut microbiota and malarial parasites. Hypotheses relating bacterial symbionts and eukaryotic parasitism have rarely been tested among humans and domestic animals, and to our knowledge have not been tested in wild vertebrates. In this study, we used Afrotropical bats, hematophagous ectoparasitic bat flies, and haemosporidian (malarial) parasites vectored by bat flies as a model to test the hypothesis that the vertebrate host microbiome is linked to parasitism in a wild system. We identified significant correlations between bacterial community composition of the skin and dipteran ectoparasite prevalence across four major bat lineages, as well as striking differences in skin microbial network characteristics between ectoparasitized and nonectoparasitized bats. We also identified links between the oral microbiome and presence of malarial parasites among miniopterid bats. Our results support the hypothesis that microbial symbionts may serve as indirect mediators of parasitism among eukaryotic hosts and parasites.

As an obligate ectoparasite of bats, the bat fly Trichobius frequens (Diptera: Streblidae) inhabits the same subterranean environment as their nocturnal bat hosts. In this study, we characterize the macromorphology, optical architecture, rhabdom anatomy, photoreceptor absorbance, and opsin expression of the significantly reduced visual system in T. frequens resulting from evolution in the dark. The eyes develop over a 21–22 day pupal developmental period, with pigmentation appearing on pupal day 11. After eclosion as an adult, T. frequens eyes consist of on average 8 facets, each overlying a fused rhabdom consisting of anywhere from 11 to 18 estimated retinula cells. The dimensions of the facets and fused rhabdoms are similar to those measured in other nocturnal insects. T. frequens eyes are functional as shown by expression of a Rh1 opsin forming a visual pigment with a peak sensitivity to 487 nm, similar to other dipteran Rh1 opsins. Future studies will evaluate how individuals with such reduced capabilities for spatial vision as well as sensitivity still capture enough visual information to use flight to maneuver through dark habitats.

This paper describes and illustrates a new species of Laboulbeniales (Ascomycota, Laboulbeniomycetes) recovered from

The aim of this study was to report on bat flies collected from a fruit bat (

Bats are parasitized by numerous lineages of arthropods, of which bat flies (Diptera, Nycteribiidae and Streblidae) are the most conspicuous. Bat flies themselves can be parasitized by Laboulbeniales, fungal biotrophs of arthropods. This is known as hyperparasitism, a severely understudied phenomenon. Three genera of Laboulbeniales occur on bat flies: Arthrorhynchus on Nycteribiidae, Gloeandromyces and Nycteromyces on Streblidae. In this review we introduce the parasitic partners in this tripartite system and discuss their diversity, ecology, and specificity patterns, alongside some important life history traits. Furthermore, we cover recent advances in the study of the associations between bat flies and Laboulbeniales, which were neglected for decades. Among the most immediate needs for further studies are detailed tripartite field surveys. The vermin only teaze and pinch Their foes superior by an inch So, naturalists observe, a flea Has smaller fleas that on him prey; And these have smaller still to bite 'em, And so proceed ad infinitum. Jonathan Swift (On Poetry: A Rhapsody, 1733).

Dispersal influences the evolution and adaptation of organisms, but it can be difficult to detect. Host-specific parasites provide information about the dispersal of their hosts and may be valuable for examining host dispersal that does not result in gene flow or that has low signals of gene flow. We examined the population connectivity of the buffy flower bat

Study of all flies (Diptera) collected for one year from a four-hectare (150 x 266 meter) patch of cloud forest at 1,600 meters above sea level at Zurquí de Moravia, San José Province, Costa Rica (hereafter referred to as Zurquí), revealed an astounding 4,332 species. This amounts to more than half the number of named species of flies for all of Central America. Specimens were collected with two Malaise traps running continuously and with a wide array of supplementary collecting methods for three days of each month. All morphospecies from all 73 families recorded were fully curated by technicians before submission to an international team of 59 taxonomic experts for identification. Overall, a Malaise trap on the forest edge captured 1,988 species or 51% of all collected dipteran taxa (other than of Phoridae, subsampled only from this and one other Malaise trap). A Malaise trap in the forest sampled 906 species. Of other sampling methods, the combination of four other Malaise traps and an intercept trap, aerial/hand collecting, 10 emergence traps, and four CDC light traps added the greatest number of species to our inventory. This complement of sampling methods was an effective combination for retrieving substantial numbers of species of Diptera. Comparison of select sampling methods (considering 3,487 species of non-phorid Diptera) provided further details regarding how many species were sampled by various methods. Comparison of species numbers from each of two permanent Malaise traps from Zurquí with those of single Malaise traps at each of Tapantí and Las Alturas, 40 and 180 km distant from Zurquí respectively, suggested significant species turnover. Comparison of the greater number of species collected in all traps from Zurquí did not markedly change the degree of similarity between the three sites, although the actual number of species shared did increase. Comparisons of the total number of named and unnamed species of Diptera from four hectares at Zurquí is equivalent to 51% of all flies named from Central America, greater than all the named fly fauna of Colombia, equivalent to 14% of named Neotropical species and equal to about 2.7% of all named Diptera worldwide. Clearly the number of species of Diptera in tropical regions has been severely underestimated and the actual number may surpass the number of species of Coleoptera. Various published extrapolations from limited data to estimate total numbers of species of larger taxonomic categories (e.g., Hexapoda, Arthropoda, Eukaryota, etc.) are highly questionable, and certainly will remain uncertain until we have more exhaustive surveys of all and diverse taxa (like Diptera) from multiple tropical sites. Morphological characterization of species in inventories provides identifications placed in the context of taxonomy, phylogeny, form, and ecology. DNA barcoding species is a valuable tool to estimate species numbers but used alone fails to provide a broader context for the species identified.

Background: We present information on Nycteribiidae flies parasitizing the bat families Pteropodidae, Miniopteridae and Vespertilionidae from the Malagasy Region, contributing insight into their diversity and host preference.Results: Our phylogenetic analysis identified nine clusters of nycteribiid bat flies on Madagascar and the neighbouring Comoros Archipelago. Bat flies sampled from frugivorous bats of the family Pteropodidae are monoxenous: Eucampsipoda madagascariensis, E. theodori and Cyclopodia dubia appear wholly restricted to Rousettus madagascariensis, R. obliviosus and Eidolon dupreanum, respectively. Two different host preference patterns occurred in nycteribiids infecting insectivorous bats. Flies parasitizing bats of the genera Miniopterus (Miniopteridae) and Myotis (Vespertilionidae), namely Penicillidia leptothrinax, Penicillidia sp. and Nycteribia stylidiopsis, are polyxenous and showed little host preference, while those parasitizing the genera Pipistrellus and Scotophilus (both Vespertilionidae) and referable to Basilia spp., are monoxenous. Lastly, the inferred Bayesian phylogeny revealed that the genus Basilia, as currently configured, is paraphyletic.Conclusion: This study provides new information on the differentiation of nycteribiid taxa, including undescribed species. Host preference is either strict as exemplified by flies parasitizing fruit bats, or more relaxed as found on some insectivorous bat species, possibly because of roost site sharing. Detailed taxonomic work is needed to address three undescribed nycteribiid taxa found on Pipistrellus and Scotophilus, tentatively allocated to the genus Basilia, but possibly warranting different generic allocation.

Background Bat flies (Streblidae and Nycteribiidae) are among the most specialized families of the order Diptera. Members of these two related families have an obligate ectoparasitic lifestyle on bats, and they are known disease vectors for their hosts. However, bat flies have their own ectoparasites: fungi of the order Laboulbeniales. In Europe, members of the Nycteribiidae are parasitized by four species belonging to the genus Arthrorhynchus. We carried out a systematic survey of the distribution and fungus-bat fly associations of the genus in central Europe (Hungary, Romania). Results We encountered the bat fly Nycteribia pedicularia and the fungus Arthrorhynchus eucampsipodae as new country records for Hungary. The following bat-bat fly associations are for the first time reported: Nycteribia kolenatii on Miniopterus schreibersii, Myotis blythii, Myotis capaccinii and Rhinolophus ferrumequinum; Penicillidia conspicua on Myotis daubentonii; and Phthiridium biarticulatum on Myotis capaccinii. Laboulbeniales infections were found on 45 of 1,494 screened bat flies (3.0%). We report two fungal species: Arthrorhynchus eucampsipodae on Nycteribia schmidlii, and A. nycteribiae on N. schmidlii, Penicillidia conspicua, and P. dufourii. Penicillidia conspicua was infected with Laboulbeniales most frequently (25%, n = 152), followed by N. schmidlii (3.1%, n = 159) and P. dufourii (2.0%, n = 102). Laboulbeniales seem to prefer female bat fly hosts to males. We think this might be due to a combination of factors: female bat flies have a longer life span, while during pregnancy female bat flies are significantly larger than males and accumulate an excess of fat reserves. Finally, ribosomal DNA sequences for A. nycteribiae are presented. Conclusions We screened ectoparasitic bat flies from Hungary and Romania for the presence of ectoparasitic Laboulbeniales fungi. Arthrorhynchus eucampsipodae and A. nycteribiae were found on three species of bat flies. This study extends geographical and host ranges of both bat flies and Laboulbeniales fungi. The sequence data generated in this work contribute to molecular phylogenetic studies of the order Laboulbeniales. Our survey shows a complex network of bats, bat flies and Laboulbeniales fungi, of which the hyperparasitic fungi are rare and species-poor. Their host insects, on the other hand, are relatively abundant and diverse. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2022-y) contains supplementary material, which is available to authorized users.

Bat flies are a diverse clade of obligate ectoparasites on bats. Like most blood-feeding insects, they harbor endosymbiotic prokaryotes, but the origins and nature of these symbioses are still poorly understood. To expand the knowledge of bacterial associates in bat flies, the diversity and evolution of the dominant endosymbionts in six of eight nominal subfamilies of bat flies (Streblidae and Nycteribiidae) were studied. Furthermore, the localization of endosymbionts and their transmission across developmental stages within the family Streblidae were explored. The results show diverse microbial associates in bat flies, with at least four ancestral invasions of distantly related microbial lineages throughout bat fly evolution. Phylogenetic relationships support the presence of at least two novel symbiont lineages (here clades B and D), and extend the geographic and taxonomic range of a previously documented lineage (“Candidatus Aschnera chinzeii ”; here clade A). Although these lineages show reciprocally monophyletic clusters with several bat fly host clades, their phylogenetic relationships generally do not reflect current bat fly taxonomy or phylogeny. However, within some endosymbiont clades, congruent patterns of symbiont-host divergence are apparent. Other sequences identified in this study fall into the widely distributed, highly invasive, insect-associated Arsenophonus lineage and may be the result of symbiont replacements and/or transient infections (here clade C). Vertical transmission of endosymbionts of clades B and D is supported by fluorescent signal (fluorescent in situ hybridization [FISH]) and microbial DNA detection across developmental stages. The fluorescent bacterial signal is consistently localized within structures resembling bacteriomes, although their anatomical position differs by host fly clade. In summary, the results suggest an obligate host-endosymbiont relationship for three of the four known symbiont clades associated with bat flies (clades A, B, and D).

This catalog presents eight species distributed among two genera and one subfamily of nycteribiid bat flies recorded in Colombia. For each genus we present synonymies and type species, and for each species account we present synonymies, disposition of type material, and specific localities and departments.

This catalog presents 73 species distributed among 19 genera and three subfamilies of streblid bat flies recorded in Colombia. For each genus we present synonymies and type species, and for each species account we present synonymies, type host, disposition of type material, and specific localities and departments for records known from Colombia.

We investigated previously unknown associations between bacterial endosymbionts and bat flies of the subfamily Nycterophiliinae (Diptera, Streblidae). Molecular analyses revealed a novel clade of Gammaproteobacteria in Nycterophilia bat flies. This clade was not closely related to Arsenophonus -like microbes found in its sister genus Phalconomus and other bat flies. High population infection rates in Nycterophilia across a wide geographic area, the presence of the symbionts in pupae, the general codivergence between hosts and symbionts, and high AT composition bias in symbiont genes together suggest that this host-symbiont association is obligate in nature and ancient in origin. Some Nycterophilia samples (14.8%) also contained Wolbachia supergroup F ( Alphaproteobacteria ), suggesting a facultative symbiosis. Likelihood-based ancestral character mapping revealed that, initially, obligate symbionts exhibited association with host-specific Nycterophilia bat flies that use a broad temperature range of cave environments for pupal development. As this mutualism evolved, the temperature range of bat flies narrowed to an exclusive use of hot caves, which was followed by a secondary broadening of the bat flies' host associations. These results suggest that the symbiosis has influenced the environmental tolerance of parasite life history stages. Furthermore, the contingent change to an expanded host range of Nycterophilia bat flies upon narrowing the ecological niche of their developmental stages suggests that altered environmental tolerance across life history stages may be a crucial factor in shaping parasite-host relationships.

As part of the 65th Medical Brigade, U.S. Army, arthropod-borne disease surveillance program and in collaboration with the Korea National Institute of Biological Resources (NIBR), bats were captured from caves and abandoned mines in the Republic of Korea. A total of 39 adult bat flies including five species of Nycteribiidae [Penicillidia jenynsii, Nycteribia parvula, N. formosana, N. allotopa mikado, and an unidentified species of Nycteribia (N. cf. formosana)], and one species of Streblidae, Brachytarsina kanoi, were collected from bats belonging to two families, Rhinolophidae and Vespertilionidae. This is the first report of N. allotopa mikado and N. formosana from the Republic of Korea.

A new species of Joblingia DybasWenzel, 1947, collected on the bat Myotis ruber (E. Geoffroy) in Southern Brazil, is described, and the type-species, J. schmidti DybasWenzel, 1947, redescribed. The diagnosis of the genus is amended. The external morphology and postgonites of both species are figured. Geographical distribution and host-parasite relationships are discussed.

We examined the correlations between prevalence (proportion of infested individuals), mean intensity (number of parasites per infested individual), and the number of bat fly species parasitizing bats in Venezuela with host body mass, distribution, and abundance. Of 133 bat species sampled, 53 species in six families were captured frequently enough to allow estimation of their parasite loads. Over all species and six families, prevalence and mean intensity were uncorrelated with these variables, but the number of fly species was correlated with host body mass. Correlations of parasitism with body mass were strengthened among the 44 species of Phyllostomidae. Earlier studies showed that bat roosting habits influence their parasitism by bat flies with more permanent, enclosed roosts being with heavier parasitism. Multiple regressions of all measures of parasitism showed that roosting habits and host body mass, respectively, were the first variables to enter stepwise regressions, together accounting for 20-43% of the variation in measures of parasitism. Lack of correlation between proxies of distribution and abundance with parasitism is taken to indicate that proximate factors such as host-as-habitat, social groupings, and roost microhabitat take precedence over species-wide attributes like commonness and ubiquity.

Experimental approaches provide insight into the dynamics of species competition and coexistence, but studies of ectoparasitic arthropods are rare. Host choice experiments were undertaken in Amazonian Peru, by using obligate bat fly parasites of Seba's short-tailed bat, Carollia perspicillata (L.). The fly species Trichobius joblingi Wenzel strongly preferred clean hosts to those previously infested with individuals of T. joblingi. Abundance thresholds may limit conspecific parasites on host individuals, and similar morphologies and habitat use may increase intraspecific competition among individuals of T. joblingi. T. joblingi did not distinguish between clean hosts and those previously infested with flies of another species, Speiseria ambigua Kessel. Results suggest that the presence of a morphologically dissimilar species does not preclude subsequent colonization. Differential microhabitat selection, aided by adaptive morphology, may facilitate species coexistence among ectoparasitic bat fly species.

Background Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date. Methods We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities. Results All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure. Conclusions The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of bat flies between the three Pteropus species in the region. We demonstrate the utility of parasite genetics as an additional layer of information to measure host movement and interspecific host contact. These approaches may have wide implications for understanding zoonotic, epizootic, and enzootic disease dynamics. Bat flies may play a role as vectors of disease in bats, and their competence as vectors of bacterial and/or viral pathogens is in need of further investigation.

International audience; Bats and their parasites are increasingly investigated for their role in maintenance and transmission of potentially emerging pathogens. The islands of the western Indian Ocean hold nearly 50 bat species, mostly endemic and taxonomically well studied. However, investigation of associated viral, bacterial, and external parasites has lagged behind. In the case of their ectoparasites, more detailed information should provide insights into the evolutionary history of their hosts, as well as pathogen cycles in these wild animals. Here we investigate species of Nycteribiidae, a family of obligate hematophagous wingless flies parasitizing bats. Using morphological and molecular approaches, we describe fly species diversity sampled on Madagascar and the Comoros for two cave-roosting bat genera with contrasting ecologies: Miniopterus and Rousettus. Within the sampling area, 11 endemic species of insect-feeding Miniopterus occur, two of which are common to Madagascar and Comoros, while fruit-consuming Rousettus are represented by one species endemic to each of these zones. Morphological and molecular characterization of flies reveals that nycteribiids associated with Miniopterus bats comprise three species largely shared by most host species. Flies of M. griveaudi, one of the two bats found on Madagascar and certain islands in the Comoros, belong to the same taxon, which accords with continued over-water population exchange of this bat species and the lack of inter-island genetic structuring. Flies parasitizing Rousettus belong to two distinct species, each associated with a single host species, again in accordance with the distribution of each endemic bat species.

Recently, a growing number Bartonella spp. have been identified as causative agents for a broadening spectrum of zoonotic diseases, emphasizing their medical importance. Many mammalian reservoirs and vectors however are still unknown, hindering our understanding of pathogen ecology and obscuring epidemiological connections. New Bartonella genotypes were detected in a global sampling of 19 species of blood-feeding bat flies (Diptera, Hippoboscoidea, Nycteribiidae, Streblidae) from 20 host bat species, suggesting an important role of bat flies in harboring bartonellae. Evolutionary relationships were explored in the context of currently known Bartonella species and genotypes. Phylogenetic and gene network analyses point to an early evolutionary association and subsequent radiation of bartonellae with bat flies and their hosts. The recovery of unique clades, uniting Bartonella genotypes from bat flies and bats, supports previous ideas of these flies potentially being vectors for Bartonella. Presence of bartonellae in some female bat flies and their pupae suggests vertical transmission across developmental stages. The specific function of bartonellae in bats and bat flies remains a subject of debate, but in addition to pathogenic interactions, parasitic, mutualistic, or reservoir functions need to be considered.

Environmental conditions, including anthropogenic disturbance, can significantly alter host and parasite communities. Yet, our current knowledge is based mainly on endoparasites, while ectoparasites remain little studied. We studied the indirect effects of anthropogenic disturbance (human population density) and climate (temperature, precipitation and elevation) on abundance of highly host-specific bat flies in four Neotropical bat species across 43 localities in Venezuela. We formulated a set of 11 a priori hypotheses that included a combination of the two effectors and host species. Statistically, each of these hypotheses was represented by a zero-inflated negative binomial mixture model, allowing us to control for excess zeros in the data. The best model was selected using Akaike's information criteria. Fly abundance was affected by anthropogenic disturbance in Artibeus planirostris, Carollia perspicillata and Pteronotus parnellii, but not Desmodus rotundus. Climate affected fly abundance in all bat species, suggesting mediation of these effects via the host or by direct effects on flies. We conclude that human disturbance may play a role in shaping bat-bat fly interactions. Different processes could determine fly abundance in the different bat species.

Basilia (Basilia) dubiaquercus sp. nov. (Diptera: Nycteribiidae) is described. The new species was collected from the bat Bauerus dubiaquercus (Van Gelder) (Chiroptera: Vespertilionidae) in Honduras. The habitus, abdomen, and male terminalia are figured. Placement of the new species among established species groups of Basilia (Basilia), as well as the conservation status of the species, is discussed.

We studied the deposition of pupae of the winged bat fly Trichobius sp. (caecus group; Diptera), an ectoparasite of Natalus stramineus (Chiroptera, Natalidae), in a natural cave in Tamaulipas, Mexico. For the first time, we show a strong spatial segregation of populations of a streblid bat fly at different stages of development. Using molecular techniques we were able to match developmental stages to adults. Only 5 pupae were present in the main bat roosts. The overwhelming majority occurred exclusively in the bat flyway passages at a considerable distance from roosting bats. Pupal density corresponded positively with the average flight height of bats in the cave passage. Taken together, observations suggest that these ectoparasites must actively seek out their hosts by moving onto passing or roosting bats. The scarceness of pupae in the main roost may be dictated by environmental constraints for their development. The estimated population of viable pupae far exceeds the population of imagoes on the bats, and predation on adults by spiders is common.

Host specificity gauges the degree to which a parasite occurs in association with a single host species. The measure is indicative of properties of the host and parasite, as well as their ecological and co-evolutionary relationships. Host specificity is influenced by the behavior and ecology of both parasite and host. Where parasites are active, vagile and coupled with hosts whose behavior and ecology brings the parasite into contact with many potential hosts, the likelihood of host switching is increased, usually leading to lowered specificity. Bat flies are specialized, blood-feeding ectoparasites of bats worldwide. In the bat fly – bat system, numerous properties interrupt the linkage of parasite to host and should decrease specificity. For bat flies these include high levels of activity, proclivity to abandon a disturbed host, the ability to fly, and a life-history strategy that includes a pupal stage decoupled from the host. For bats these include rapid, frequent and wide-ranging flight, high species richness encouraging inter-specific encounters during foraging, roosting and reproductive events, the utilization of large, durable roosting structures that are often shared with other bat species, and utilization of common entrance/exit flyways. The biological and ecological characteristics of bats and flies should together facilitate interspecific host transfers and, over time, lead to non-specific host-parasite associations. Large surveys of Neotropical mammals and parasites, designed to eliminate artifactual host-to-host parasite transfers, unequivocally demonstrate the high host specificity of bat flies. High degrees of specificity are remarkable in light of myriad host and parasite characteristics that ought to break down such specificity. Although host-specific parasites often have limited dispersal capability, this is not the case for some groups, including active, mobile bat flies. Host specificity in parasites with high dispersal capability is likely related to adaptive constraints. Among these may be a reproductive filter selecting for specificity based on mate availability, and co-evolved immunocompatibility where parasites use the same or similar immune-signaling molecules as their hosts to avoid immunological surveillance and response.

An extensive survey of the ectoparasites infesting bats in Paraguay provides information regarding the taxonomy and host distribution of streblid bat flies at a geographic interface between subtropical and temperate habitats. Five families of bats representing 45 species, including Molossidae (5 genera and 15 species), Natalidae (1 genus and 1 species), Phyllostomidae (11 genera and 15 species), Noctilionidae (1 genus and 2 species), and Vespertilionidae (4 genera and 12 species) were collected from 24 localities across Paraguay and sampled for ectoparasites. In total, 2,467 bat flies were collected, representing 11 genera and 31 nominal species of Streblidae, of which 6 genera and 24 species are new records for Paraguay. No streblids were collected from vespertilionid bats; 23 species infested phyllostomids, 6 species noctilionids, 1 species a natalid, and 1 species molossids. Streblid bat flies were highly specific to certain host groups and individual host species, and their geographic distributions closely followed those of their host bats. Of 31 streblid species surveyed, 27 were monoxenous (i.e., associated with a single host species), and 4 were stenoxenous (i.e., associated with a group of phylogenetically related hosts). The number of streblid species is greatly reduced in the Chaco region west of the Paraguay River, largely because of the lack of phyllostomid host bats.

An extensive survey of ectoparasitic nycteribiid flies infesting bats in Paraguay provides information about their taxonomy and hosts at a geographic interface between subtropical and temperate habitats. During the study, 2,931 bats representing five families, 22 genera, and 45 species were captured and sampled for ectoparasites. Of these, 86 individuals belonging to six species of vespertilionid bats, and one individual of a molossid bat, harbored 150 fly specimens. We identified five species of Basilia Miranda-Ribeiro, with one, Basilia juquiensis Guimarães, representing a new record for Paraguay. In total, six species of Basilia have been reported to occur in Paraguay.

A new species of Metelasmus Coquillett, 1907 (Diptera: Streblidae: Streblinae) from Sturnira lilium (E. Geoffroy, 1810) (Chiroptera: Phyllostomidae: Stenodermatinae) is described. Drawings of the frontoclypeus, epiproct, gonopods, postgena, postvertex and occiputs, tergite VII, and wing are presented. Host relationships of Metelasmus are discussed.