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Figure 1. The skull of the world’s smallest living bat, the tiny bumblebee bat, Craseonycteris thonglongyai (right), next to those of two of Africa’s largest insectivorous bats, Macronycteris gigas (bottom) and Scotophilus alvenslebeni (top). Scale bar = 10 mm (© F. P. D. Cotterill).
The oldest known bat fossil, Onychonycteris finneyi, was discovered recently in fossil beds in Wyoming, USA, and dates to 52 million years ago. Its diagnostic characters are intermediate between bats and non-flying mammals (Simmons et al. 2008). The fossil bat species had claws on each finger and relatively long hind legs in relation to its forelimbs, similar in ratio to sloths and lemurs. Its short, broad wings indicate that it probably alternated between flapping flight and gliding, and that it was also capable of clambering in trees. The small cochlea (ear) bones show that it could not echolocate, suggesting that flight evolved before echolocation in bats. By 50 million years ago, during the Eocene, there were already at least three families and 13 species of bats. Eocene fossil bats are known from North America, Europe and Australia. All these ancestors were already fully developed as bats, although they did not closely resemble extant species. Recent discoveries in Egypt of extinct bats from the late Eocene and early Oligocene (37–27 million years ago), which appear more closely related to modern species, suggest that bats may have diversified in Africa following migration of primitive ancestors from Europe (Gunnell et al. 2008).
Taxonomic classifications are essential to the universal communication of verifiable scientific knowledge (Cotterill 1995a, Ghiselin 2005), in which descriptions of species, and any other taxon, should adhere to scientific conventions of nomenclature (Winston 1999, Gardner and Hayssen 2004). In this respect, the persisting confusion over the real species diversity of African house bats (genus Scotophilus) testifies to why precise and accurate taxonomy is so critical to all of biology and conservation. This example especially highlights the relevance of type material, preserved in museums, if we are to apply scientific evidence to clarify the distinctiveness of a population in a taxonomic revision. Thus, where our own research on collections or published evidence allows, we have detailed respective type material (the holotype, syntype or lectotype) for each of the 125 species in the species accounts section, which also discusses related taxa of biogeographical relevance, where the status of synonyms and purported subspecies is currently unresolved in relation to the nominate taxon. Nevertheless, this book does not provide an exhaustive synonymy, for which full taxonomies are available (Meester et al. 1986, Ansell 1989, Simmons 2005).
Selected from among several competing alternatives, the concept of the species category has radical impacts on how biodiversity is classified. With respect to the diversity of living bats, the taxonomic treatment of Simmons (2005) is based primarily on a Phylogenetic Species Concept (PSC), as an operational criterion of the Evolutionary Species Concept (ESC) (see Cotterill 2002a, Cotterill et al. 2014 and Taylor et al. 2019a for discussion). Different choices of species concept have significant consequences on a taxonomy, and thus any facet of knowledge of a group of organisms. Although the authors of this book are not in total agreement on the scientific relevance of the subspecies concept, we have recognised phylogenetically distinct populational lineages as specifically distinct; we have highlighted existing microtaxonomic problems in this context. Where listed, the subspecies category serves to flag populations of current uncertain taxonomic status, which await revision using modern taxonomic methods and molecular evidence (Cotterill et al. 2014, Taylor et al. 2019a).
The most recent published list of mammalian species (Burgin et al. 2018) recognised 1,386 species of bats in the world (up from 1,115 species reported in the 2010 edition of this book); this is one-fifth of the total 6,495 mammalian species listed. Since the publication of the list, the total number of bats has increased to 1,411 species, according to the database maintained by Burgin and colleagues (Mammal Diversity Database 2019). In a different database, dedicated to listing all the bat species in the world, the number of species now sits at 1,406 (Simmons and Cirranello 2019). We expect this number to continue increasing for the foreseeable future.
This book presents the most comprehensive account, to date, of the bats of southern Africa, and is an update of the first edition, published in 2010. This synthesis of knowledge is underpinned by extensive specimen collections housed in southern Africa, as well as in overseas museums. We have compiled species accounts for the 125 species of bats known to occur in the southern African region. This synthesis of knowledge is accompanied by identification matrices, distribution maps, sonograms, photographs of bats and their skulls, and tables of measurements.
GEOGRAPHICAL SCOPE
In this book, we define southern Africa in its broadest, biogeographical context as the southern third of the continent, including a large portion of Central Africa. The book covers the southern African subregion, as well as all of Angola, Malawi, Zambia, Mozambique, and the southern portion of the Democratic Republic of the Congo (DRC). The northern boundary is set at 4°S; this line of latitude extends east to the western shore of Lake Tanganyika (Figure 2). This definition – pertinently the northern boundary at 4°S – extends the region recognised by previous workers, notably Ellerman et al. (1953) and Werger (1978), who placed a northern limit of 10°S on their studies of southern Africa. The syntheses of Smithers (1983) and Meester et al. (1986) were even more tightly restricted to the southern African subregion south of the Kunene and Zambezi rivers. Nevertheless, these treatments, including that of this book, all exclude the political region of East Africa, the main forest belt of the Congo basin, and the principal portion of the Albertine Rift.
Figure 2. Outline of the study area covered in this book: southern and Central Africa south of the bold line. It includes all of Angola, Botswana, Lesotho, Malawi, Mozambique, Namibia, South Africa, Eswatini (formerly Swaziland), Zambia, Zimbabwe and the southern half of the Democratic Republic of the Congo.
Within practical limits, the geographical scope of this synthesis of southern and Central African Chiroptera includes all known literature and museum records. So in addition to all the taxa known to occur throughout the southern African subregion, our biogeographical coverage incorporates important records for Central Africa. This includes the wealth of data compiled by Hayman et al. (1966), additional to Crawford-Cabral (1989) and Ansell (1978) for Angola and Zambia, respectively.
It is important to justify such a vast coverage, extending north of the southern African subregion to include all of Angola, Malawi, Mozambique and Zambia, and much of the southern DRC. Beyond incorporating bat faunas of the southwestern arid and southern savanna biomes, this coverage adds many bats that augment the region’s chiropteran diversity significantly. The occurrence of these interesting species reflects a key determinant of habitat, represented in the mesic savannas of the Zambesian phytochorion, and the Guinea–Congolia/Zambesia Transition Zone. These habitats dominate the vegetation of northern Angola and the southern Congo basin (White 1983). The biodiversity of the evergreen gallery forests is of special biogeographical significance, because of the high complement of Guinea–Congolian species (additional to local elements of Afromontane affinities); these forest-associated bats increase the overall diversity (see Biogeography for more detail and maps).
The pattern of occurrence of these Guinea–Congolian elements (including notable Chiroptera) exhibits a clustering in the landscape, because they are restricted to forest patches that form a mosaic in the encompassing savanna. This forest–savanna mosaic is structured along a latitudinal gradient. Its extent and composition reflects closely on the subcontinental trend in rainfall, which increases northwards; thus, the vegetation of south-central Africa grades from savanna in the south, through a savanna–forest mosaic, into the closed, high forests closer to the equator. Influences of this association between climate, landscape and vegetation on the biodiversity extend far beyond the main forest belt of the equatorial Congo, for even landscapes south of the Great Equatorial Divide (the Congo–Zambezi