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ОглавлениеHypsignathus monstrosus H. Allen 1862
Hammer-headed fruit bat Least Concern
Description: Hypsignathus monstrosus is the largest bat in mainland Africa with a mass of well over 300 g in adult males and over 200 g in adult females. The wingspan can exceed 91 cm. The pelage is sepia-brown to reddish-brown with white speckling on the belly. The wings are dark brown. Adult males are much larger than females, and may be distinguished by an enormous cylindrical muzzle with a blunt end. The muzzle of the female is not as exaggerated as that of the male. The face, head and shoulders are greyish with an indistinct dark line running along the midline of the top of the muzzle, which is partially devoid of hair or covered by very short hair. There is a small dark patch at the base of each long hair on the pale muzzle, giving a spotted appearance. Shoulder epaulettes are absent in both sexes. The ears have a patch of white fur at their base.
The skull is massive with moderate zygomatic arches. In lateral profile, the rostrum is deep, slightly rounded, and greatly elevated above the dental line. Sexual dimorphism in this feature is pronounced, with males having a much deeper rostrum than females. The sagittal crest is moderately to well developed, while the lambdoid crest is well developed. There are 10 or 11 palatal ridges present; the first five are thick, while the rest are thinner and somewhat irregular. The dental formula is 2121/2132 = 28. The first lower premolar is minute (Rosevear 1965).
Key identification features: The combination of large size (FA > 110 mm) and shape of muzzle clearly distinguishes Hypsignathus monstrosus from all other African bats.
Echolocation call: This bat does not echolocate.
Distribution, habitat and roosting: Hypsignathus monstrosus is a common rainforest inhabitant of Central and West Africa, but is marginal to southern Africa. So far, it has only been recorded from the southwestern DRC and northern Angola. However, it may be more widely distributed in the far northern parts of Angola and southwestern DRC than shown in the map. The type locality is not known for certain, but may be in Gabon (Happold 2013g).
The southern African population of this species is poorly represented in museums, with only eight records examined for this book.
Nothing is known about its roosting habits in southern Africa, but in West Africa it roosts singly or in small groups in trees (Rosevear 1965). It is associated with closed forest and riverine habitats, but may venture into orchards to feed on fruiting trees that are situated close to forest.
Extralimital: Hypsignathus monstrosus is widespread in tropical African forests in Kenya, Uganda, southern Sudan, DRC, Congo, Central African Republic, Gabon, Cameroon, Equatorial Guinea, Nigeria, Benin, Togo, Ghana, Côte d’Ivoire, Liberia, Burkina Faso and Sierra Leone (Bergmans 1989).
| External and cranial measurements (mm) and mass (g) for Hypsignathus monstrosus, males and females presented separately | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean | Min | Max | SD | N | Mean | Min | Max | SD | N | ||
| Males | Females | ||||||||||
| Mass 1 | 393.0 | 374.0 | 412.0 | - | 2 | Mass 1 | 232.0 | 208.0 | 256.0 | - | 3 |
| FA 1 | 131.0 | 128.0 | 134.0 | - | 2 | FA 1 | 114.0 | 108.5 | 118.5 | - | 3 |
| Total 2 | - | 220 | 275 | - | - | Total 2 | - | 195 | 220 | - | - |
| Tail 2 | 0 | - | - | - | - | Tail 2 | 0 | - | - | - | - |
| Tibia 1 | - | 54 | 60 | - | - | Tibia 2 | - | 52 | 55 | - | - |
| Ear | - | - | - | - | - | Ear | - | - | - | - | - |
| CI 3 | 59.1 | 57.3 | 60.8 | - | 2 | CI 3 | 68.7 | - | - | - | 1 |
1 Wolton et al. (1982) based on specimens from Liberia 2 Rosevear (1965) 3 Specimens measured by the authors; males were juveniles, while female was adult
Figure 61. Skull and teeth of Hypsignathus monstrosus: (a) dorsal view, (b) ventral view, (c) lateral view, and (e) lateral mandible view of male (P 3079, Makerere University, Kampala), and (d) lateral view of female specimen (unnumbered, Makerere University, Kampala).
Foraging ecology: Hypsignathus monstrosus has broad wings with high wing loading (36.3 N .m-2) and low aspect ratio (6. 7) (Norberg and Rayner 1987). There is no information on the diet of this species for southern Africa, but elsewhere it feeds on the following plants: Mangifera indica, Annona spp., Ceiba spp., Musanga cecropioides, Anthocleista spp., Chlorophora spp., Ficus lyrata, F. ovata, F. scott-elliotii, Musa spp., Psidium guajava, Adenia cissampeloides, and Solanum spp. (Fujita and Tuttle 1991). Soft fruit is plucked while hovering and taken to a nearby perch where the juice is squeezed out and the rest discarded (Rosevear 1965, Kingdon 1974).
Reproduction: No reproductive information is available for southern Africa. In East Africa, males form leks in which several individuals will call within the same tree (Bradbury 1977). One, or rarely two, young may be born throughout the year (Kingdon 1974).
Figure 62. Hypsignathus monstrosus: (a) roosting female showing dark line along midline of muzzle, and (b) close-up of male showing the enormous muzzle (Liberia, © A. Monadjem).
SYSTEMATIC NOTES
1862.Hypsignathus monstrosus H. Allen, Proc. Acad. Nat. Sci. Philadelphia 13(11): 157. ‘West Africa’ (= Gabon).
The diploid number in H. monstrosus is 2n = 36 and FN = 68 (Haiduk et al. 1980).
1 Wolton et al. (1982) based on specimens from Liberia
2 Rosevear (1965)
3 Specimens measured by the authors; males were juveniles, while female was adult
