﻿Nycteribiid bat flies (Arthropoda, Insecta, Diptera, Nycteribiidae) of Kenya

﻿Abstract Bat flies (Diptera: Nycteribiidae and Streblidae) are hematophagous ectoparasites of bats characterized by viviparous pupiparity and generally high host specificity. Nycteribiid bat flies are wingless, morphologically constrained, and are most diverse in the Eastern Hemisphere. Africa hosts approximately 22% of global bat biodiversity and nearly one-third of all African bat species occur in Kenya, one of Africa’s most bat-rich countries. However, records of nycteribiid bat fly diversity in Kenya remain sparse and unconsolidated. This paper combines all past species records of nycteribiid bat flies with records from a survey of 4,255 Kenyan bats across 157 localities between 2006 and 2015. A total of seven nycteribiid genera and 17 species are recorded, with seven species from the recent ‘Bats of Kenya’ surveys representing previously undocumented country records. Host associations and geographic distributions based on all available records are also described. This comprehensive species catalog addresses and further emphasizes the need for similar investigations of nycteribiid biodiversity across Africa.


Introduction
Bat flies (Diptera: Nycteribiidae and Streblidae) are hematophagous, obligate ectoparasites of bats worldwide.Like other members of superfamily Hippoboscoidea, they are characterized by reproduction via adenotrophic viviparity, wherein a single egg hatches and the larval instars develop within a female, nourished by specialized glands (Dick and Patterson 2006).The primary disassociation of bat flies from their hosts occurs when gravid females use the roost substrate to deposit prepupae; subsequently, flies complete their pupal development offhost and newly eclosed adults must locate and colonize a suitable host.
Bat fly morphology is well-adapted for clinging to the pelage or membranes of bats.Most species of both families possess rows of spiny ctenidia, setae modified into spines, and legs tipped in recurved claws to anchor themselves to their hosts.Many taxa have secondarily evolved winglessness (Theodor 1957a).Bat flies in the family Streblidae possess relatively diverse body plans across the genera, ranging in shape from dorsoventrally flattened to laterally compressed and from wingless to fully flighted.In contrast, members of Nycteribiidae are more morphologically uniform; all species are wingless, dorsoventrally flattened and superficially spider-like, and differ primarily in size rather than shape (Dick and Patterson 2006).
Though both Streblidae and Nycteribiidae are globally ubiquitous, particularly in the tropics and subtropics, nycteribiid bat flies are most diverse in the Eastern hemisphere (Dick and Patterson 2006), with only about 20% of described species occurring in the Western Hemisphere.Nycteribiidae is comprised of 285 species across three subfamilies and 12 genera (Dick and Patterson 2006;Graciolli and Dick 2023).Nycteribiid bat flies may exhibit lower host specificity than streblids (Verrett et al. 2022), but there have been few large and carefully collected surveys of nycteribiids to assess the degree of host specificity across the species.Further, some bat flies have been identified as vectors or hosts of bacterial pathogens and haemosporidian parasites (Megali et al. 2010;Morse et al. 2012;Lutz et al. 2016;Wilkinson et al. 2016), and can harbor viruses related to bat-associated zoonoses (Bennett et al. 2020;Ramírez-Martínez et al. 2021).Therefore, a more complete understanding of nycteribiid diversity and host associations is important for characterizing their role in disease transmission among bats.
Bat biodiversity follows a typical latitudinal trend, with nearly 80% of species concentrated in the tropics (Willig et al. 2003).More than 300 bat species have been described on the African continent (Mammal Diversity Database 2022), of which 104 species have been recorded in Kenya (Musila et al. 2019).Despite Kenya's position as supporting the richest East African bat fauna (Patterson and Webala 2012), the diversity of nycteribiid bat flies associated with this rich bat fauna remains mostly unexplored.Here we compile all known historical species records of bat flies in Kenya, in addition to identifying and cataloging nycteribiid bat flies from the 'Bats of Kenya' survey of 4,255 bats across 157 Kenyan localities between 2006 and 2015.These species accounts contribute to our understanding of the diversity, distribution, and host associations of nycteribiid bat flies in an understudied region.

Material and method
The 'Bats of Kenya' surveys were conducted by the Field Museum of Natural History in collaboration with the National Museums of Kenya, Kenya Wildlife Service, Karatina University and Maasai Mara University between 2006 and 2015 (Monadjem et al. 2020) and contributed the bulk of species records in this study.Bats were captured across 157 sampling sites from 82 localities (Table 1), primarily in western, central, and eastern Kenya (Fig. 1).Sampling of foraging and commuting bats was conducted using mist nets erected along trails and roadways, around bodies of water, or at entrance/exit flyways to roosting sites.Additional bats were collected via hand nets within roosts.The properties of roosting sites were variable, ranging from natural (e.g., caves) or relatively permanent anthropogenic structures (e.g., mines, buildings) to more ephemeral roosts (e.g., trees).Following capture, bats were transferred individually to clean cloth bags to minimize parasite disturbance transfers.Bats were euthanized using halothane for collection as museum specimens then fumigated with ethyl ether to ease the extraction of their ectoparasites.Museum specimen collection was performed in accordance with American Society of Mammalogist guidelines (Sikes et al. 2016) and with the approval of the Field Museum's Institutional Animal Care and Use Committee (most recently 2012-003).Bat flies were immediately transferred to tubes containing 95% ethanol.At the lab, nycteribiid flies were identified using keys and species accounts from Theodor (1967) and via comparison to reference specimens in the Field Museum of Natural History Collection of Hippoboscoid Diptera, where all specimens collected in this survey are currently housed.

Species accounts
The following species accounts address all known species of nycteribiid bat flies from Kenya, including historical and current records.(Theodor 1967: 465).
Distribution.Generally sub-Saharan West Africa (including Sao Tome), Central Africa, East Africa to Kenya and Tanzania (including Zanzibar).
Distribution.Subsaharan West, Central, and East Africa, apparently excluding South African subregion.
Hosts.Species of the subfamily Cyclopodiinae are largely limited to pteropodid bats.The historical records from Rousettus aegyptiacus, Myonycteris angolensis, and Epomophorous sp. are presumptively reliable.In Kenya, Dipseliopoda biannulata has been collected from Epomophorus wahlbergi and Rousettus sp.Historical records from species of Rhinolophus and Tadarida are likely erroneous associations.
Distribution.Subsaharan Central and East Africa (Uganda, Kenya, Tanzania).Hosts.Species of the subfamily Cyclopodiinae are largely limited to pteropodid bats.The historical records from Stenonycteris lanosus and Eidolon helvum are likely legitimate.
The type series comprised ca 175 specimens from Kenya, Sudan, Congo, Malawi, and South Africa.
Nakuru: 14 specimens from undetermined host, Zumpt (Theodor 1955: 204).Distribution.Subsaharan Africa, apparently excluding South Africa.Hosts and comments.Basilia robusta has previously been reported from a variety of host bats, including species of Pipistrellus and Eptesicus.In Kenya, 61 specimens were collected, largely associated with bat species in the genera Laephotis, Neoromicia, Pseudoromicia, and Pipistrellus.The single fly specimen from Scotophilus may be an accidental association.This is the first record of B. robusta from Kenya.
Hosts and comments.Penicillidia fulvida has been reported in association with a remarkable variety of bats in the families Pteropodidae, Rhinolophidae, and Hipposideridae (Suborder Yinpterochiroptera) as well as Vespertilionidae, Emballonuridae, and Nycteridae (Suborder Yangochiroptera).Theodor (1967) remarked that this species is apparently quite unspecific [to host species of bats] and had been reported from 14 species, 7 genera, and 5 families of bat.The 65 specimens of P. fulvida collected recently in Kenya were also recovered from a wide variety of host bats, with little evidence of population structure among the specimens (Verrett et al. 2022).Penicillidia fulvida is a rarity among bat flies in its demonstrable lack of host specificity, even with respect to families and suborders.
Distribution.Subsaharan Africa, apparently excluding South Africa.
Hosts.This rarely encountered species has been reported in association with a variety of species.The single specimen collected during the 'Bats of Kenya' survey was associated with Hipposideros caffer clade 1.Too few specimens exist to determine whether P. pachymela exhibits the broad host range seen in P. fulvida.
Hosts and comments.The historical records of Phthiridium tectum hav been associated with a variety of bats in the genera Miniopterus, Rhinolophus, Eptesicus, and Hipposideros.This species is apparently rare in Kenya, and no recent collections were made during the 'Bats of Kenya' survey.

Phthiridium sp. nov. from Rhinolophus clivosus
Notes.Three male specimens collected from two "Rhinolophus clivosus 2" represent a putative undescribed species.Given the lack of female specimens and that many diagnostic characteristics are associated with the female abdomen, we decline to describe this new species based on the inadequate material presently available.
Distribution.Known only from Kenya.
Hosts.The three known specimens were all collected from a Rhinolophus clivosus clade 2 individual, at the Kariandusi mines near Gilgil.

Discussion
This effort represents the most extensive catalog to date of nycteribiid biodiversity in Kenya, and one of the most thorough summaries of nycteribiid diversity in the Afrotropical region.The 'Bats of Kenya' survey documented 7 nycteribiid species previously unknown from Kenya (Basilia ansifera, B. bouvieri, B. robusta, Phthiridium hoogstraali, P. inopinata, P. rhodesiense, and P. scissum), as well as three males of a putative new species in the genus Phthiridium.These records raise the richness of nycteribiid bat flies cataloged from Kenya to 17 species in 7 genera (Appendix 1).
The geographic sampling distribution of bats across Kenya was reasonably thorough with respect to biodiversity centers.Localities sampled in the 'Bats of Kenya' survey were concentrated in the tropical forests and woodlands containing much of Kenya's bat biodiversity; gaps in coverage comprise much drier parts and brushlands in northern Kenya which are depauperate in bats.Notable exceptions are some stretches of coastal forest at or near the Somali border, including the Boni and Dodori National Reserves, which were not sampled due to security concerns.Kenya's coastal forests are recognized as global biodiversity hotspots with high degrees of endemism (Myers et al. 2000), and further sampling efforts should target this area when it is safe to do so.Further, although the unsampled northwestern and northeastern regions of Kenya are composed mainly of savanna or arid habitat with relatively few bat species (Herkt et al. 2016), elevated areas can intercept orographic precipitation and may support woodlands containing unique bat and bat fly communities (Monadjem and Reside 2008).They surely warrant future survey attention.
The most biodiverse habitats in Kenya are also those most prone to habitat loss, modification and fragmentation, as areas with higher water availability are attractive for anthropogenic use in an overall arid country (Bennun and Njoroge 2000).It is crucial for Kenyan biodiversity to be more thoroughly explored as natural areas globally are depleted by habitat loss.Moreover, habitat fragmentation can affect the size and isolation of populations (e.g., Webala et al. 2019), influencing transmission dynamics of vector-borne diseases in patterns mediated by host and parasite ecology (Suzán et al. 2012).Land conversion and habitat fragmentation, particularly in highly biodiverse areas, also increases the probability of human-wildlife interaction and can facilitate the spread of zoonotic diseases (Johnson et al. 2020).Nycteribiid bat flies are vectors of bacterial pathogens in genus Bartonella (Wilkinson et al. 2016) and of haemosporidian parasites of bats (Megali et al. 2010;Lutz et al. 2016).Bat flies are also becoming increasingly linked to viral pathogens related to bat-associated zoonoses, though their role as potential vectors or principal carriers of such diseases remains unclear (Bennett et al. 2020, Ramírez-Martínez et al. 2021).As the role of bat flies in disease transmission is further elucidated, bat fly diversity must be understood at a fundamental level in areas where it remains largely unexplored.The need to investigate bat fly vector potential and diversity is especially salient in continental Africa, which harbors 22.4% of all bat biodiversity (MDD 2022) and accounted for more than half of all emerging infectious disease outbreaks between 1996between and 2009between (Chan et al. 2010)).and Simon Musila for coordinating specimen loans.We are also grateful to Samuel Kasiki and Robert Mwasya, formerly of the Kenya Wildlife Service, for permits, access to field sites, and local transportation.We thank the Grainger Bioinformatics Center for partial funding of this study and for the coordination efforts of the collections staff at the Field Museum, especially John Phelps, Lauren Johnson, Adam Ferguson, Rebecca Banasiak, Jessica Mohlman, Stefania Briones, and the late Bill Stanley.For financial support, we thank Western Kentucky University's Biodiversity Center, Biology Department, and Graduate School, and NSF-DEB 2127292 to CWD.Field collections were funded by several agencies in cooperation with the Field Museum.The JRS Biodiversity Foundation, Field Museum's Council on Africa, Marshall Field III Fund, and Barbara E. Brown Fund for Mammal Research were critical to fieldwork and analyses, as was the support of Bud and Onnolee Trapp and Walt and Ellen Newsom.

Family Nycteribiidae Samouelle, 1819 Subfamily Cyclopodiinae Maa, 1965 Genus Cyclopodia Kolenati, 1863 Cyclopodia greeffi greeffi Karsch, 1884 Previous records, hosts, distributions. From
Each account lists previous Kenyan records (if any) including hosts and distributions, as well as 'Bats of Kenya' project records, distribution, hosts, and comments where applicable.We note that Kenyan bat diversity, including phylogeny and taxonomy/nomenclature, is in a fluid state.Ongoing genetic surveys have robustly identified well-supported clades, but some of these clades have not yet been reliably associated with bino- Demos et al. 2018, 2019 reference to "clade number" in bat species names follow recent bat publications (e.g.,Demos et al. 2018, 2019, 2020, 2023 In Press;  Patterson et al. 2020).The previous bat fly records are based on unpublished FMNH records and data compiled by the late T. C. Maa (Bernice P. Bishop Museum, Honolulu, HI USA).Host species identities reported in historical records cannot be verified and are reported as published.We have attempted to update zoological nomenclature as well as names of political units, but older nomenclature that could not be verified or updated is presented in quotation marks.Eidolon helvum (Senegal, "French West Africa", Mali, Liberia, Togolese Republic, Nigeria, Cameroon, Sao Tome, Democratic Republic of the Congo (DRC), Uganda, Sudan, Kenya), Rousettus aegyptiacus (DRC, Tanzania), Epomophorus sp.(Guinea-Bissau), Pteropus voeltzkowi (Zanzibar).Macronycteris vittatus (Ghana), Nycteris thebaica (Ghana),
Distribution.Subsaharan Africa, especially West Africa.Hosts and comments.