144.

Variegated Butterfly Bat

Glauconycteris variegata

French: Glauconyctere réticulé / German: Genetzte Schmetterlingsfledermaus / Spanish: Glauconicterio reticulado

Other common names: Butterfly Bat, Leaf-winged Bat

Taxonomy. Scotophilus variegatus Tomes, 1861,

“Otjoro,” Namibia.

Analysis of mitochondrial genes by A. Hassanin and colleagues in 2018 retrieved G. variegata as sister to all other species of Glauconycteris . Two subspecies recognized.

Subspecies

and Distribution.

G. v. variegata Tomes, 1861 — widely but patchily distributed throughout much of sub-Saharan Africa, from Atlantic coast of Senegal E to Ethiopia and S to NE Namibia, N Botswana, and NE South Africa.

G. v. phalaena Thomas, 1915 — SC Sudan and Somalia.

Descriptive notes. Head-body ¢.48-62 mm, tail 40-53 mm, ear 11-14 mm, hindfoot 7-10 mm, forearm 38-45 mm; weight 5-14 g. Females are apparently larger than males in body dimensions but not body weight. Pelage is dense and soft, with 7-10 mm middorsal hairs. Dorsal fur lacks markings and ranges from pale creamy buff to yellowish fawn, paler on head and neck in some individuals. Hairs are pale creamy buff or yellowish fawn with paler bases or creamy white with brown bases and yellowish fawn tips. Ventral fur ranges from yellowish cream to pure white, suffused with pale gray particularly on throat in some individuals. Ears are light brown, separated, and shortfor a vespertilionid, with outer margins connecting with fleshy lobe near corner of mouth and inner margins with moderately long backward-pointing lobe at base. Tragus has straight anterior margin and convex posterior margin, with inconspicuous lobe at base. Eyes are very small. Nostrils are subcylindrical and open laterally. Well-developed glandular protuberances separate nostrils by deep groove,giving swollen appearance to muzzle. Flight membranes are conspicuously reticulated. Wings and uropatagium are pale yellowish orange, with dark brown pigment outlining bones and venation. Tibia is long (18-21 mm). Baculum is very small and triangular. Skull is moderately large and has high broad braincase, short obtuse rostrum, and domed cranium without sagittal crest. Profile of forehead region is weakly concave compared with other species of Glauconycteris . Supraoccipital crest is poorly developed, and frontal region of skull is not hollowed. Basisphenoid pits are shallow and indistinct. I* is longer than I’, and they vary from unicuspid to tricuspid. I° is almost rudimentary. I is trifid or rudimentary quadrifid, with moderately developed cingulum. Incisors are pressed tightly between canines. I, and I, are much smaller than I, and coneshaped with broad, evenly developed cingula. P* is large, well developed, and carnassial. P is absent. P, and P, are small and conical, with prominent cingula that form anteroposterior cusps. Dental formula for all species of Glauconycterisis 12/3, C1/1,P 1/2, M 3/3 (<2) = 32. Chromosomal complement has 2n = 18 and FN = 32, with two pairs of metacentric, five pairs of submetacentric, and one pair of subtelocentric autosomes. X-chromosomeis medium-sized subtelocentric, and Y-chromosomeis small metacentric.

Habitat. Mainly savanna habitats, including open woodland savannas and open bush country known from elevations up to ¢. 1000 m. One female Variegated Butterfly Bat was caught in riverine forest near hot, humid, marshy grassland in Ethiopia, and another individual was caughtin dense riparian forest in Pafuri, north-eastern South Africa.

Food and Feeding. The Variegated Butterfly Bat forages by moderately fast hawking, high aboveground, mainly in uncluttered habitats, but also between trees, around lights, close to the ground, and over water. It eats airborne prey, primarily soft-bodied insects.

Breeding. The Variegated Butterfly Bat seems to be monoestrous, but seasonal reproductive cycle might vary acrossits distribution. Sexually active males were reported in July and Octoberin southern Uganda. In north-eastern DR Congo (3-4° N), three of ten females were pregnant in March, with parturition predicted in March-April. In Nairobi, Kenya (1°17° S), a lactating female was recorded in April. In Zimbabwe (16— 20° S), two pregnant females each carrying one fetus were recorded in August, and six females each with a newborn were recorded in early November. Breeding season varies across latitudes, ranging from an early boreal cycle (parturition in March-April) in the north to a late austral cycle (parturition around November) for southern populations. In northern latitudes, gestation lasts ¢.3 months, parturition occurs in April, and young are weaned through May. Litter size is 1-2, but usually one.

Activity patterns. During the day, the Variegated Butterfly Bat roosts mainly in dense clusters ofleaves in trees. It also roosts in thatch of abandoned huts. It has been found in lychee trees (Lutchi, Sapindaceae), in a Natal mahogany tree ( Trichilia emetica, Meliaceae) 7-5 m aboveground, and on a low branch of a mango tree ( Mangifera, Anacardiaceae). The species remains motionless and is reluctant to fly when disturbed. It has been observed leaving roosts in daylight (two hours before sunset) or in the beginning of the night. Aspect ratio is low, wing loading is low to very low, and wingtips are long and pointed, suggesting efficient low speed flight, but they can fly moderately fast, with moderate maneuverability. Minimum and maximum power speeds are 3-3 m/s and 4-4 m/s, respectively, and mean foraging flight speed is 4 m /s. Variegated Butterfly Bats can take off from ground. They emit audible squeaks (social calls) during flight. Echolocation vocalizationsare highintensity FM calls sweeping from 70 kHz to 30 kHz, sometimes including a second harmonic and rarely a third. Two foraging bats from Zimbabwe had smooth steep-shallow FM search-phase call shape, with mean start frequency of 53-4 kHz, mean end frequency of 33-7 kHz, mean peak frequency of37-7 kHz, mean bandwidth of 19-7 kHz, and mean call duration of 5-3 milliseconds. Approach-phase calls are shorter and broader in bandwidth.

Movements, Home range and Social organization. Variegated Butterfly Bats roost alone, in pairs, or in groups of 3-12 individuals.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Happold, M. (2013cb), Fenton (2001), Hassanin et al. (2018), Hayman & Hill (1971), Koopman (1971a, 1993), Rambaldini (2010), Simmons (2005), Thomas (1905a).