Furipterus horrens, F. Cuvier, 1828

Don E. Wilson & Russell A. Mittermeier, 2019, Furipteridae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 412-417 : 417

2.

Thumbless Bat

Furipterus horrens

French: Furiptere hérissé / German: Gemeiner Stummeldaumen / Spanish: Murciélago sin pulgar

Taxonomy. Furia horrens F. Cuvier, 1828 ,

“la Mana,” French Guiana .

R. F. Tomes in 1856 was the first to use the current name combination. Relative to DNA barcoding studies, F horrens showed a 2:5% mean intraspecific sequence divergence, which according to criteria of R. J. Baker and R. D. Bradley in 2006 could represent cryptic speciation but not distinct mitochondrial lineages or phylogroups. Monotypic.

Distribution. S Central and N South America from SW Nicaragua (Refugio Bartola), S throughout Costa Rica and Panama to Colombia, Venezuela, Trinidad I, the Guianas, Brazil, E Ecuador, E Peru, and N Bolivia.

Descriptive notes. Head-body ¢.34-41 mm (males) and 33-36 mm (females), tail 20-28 mm (males) and 21-38 mm (females), hindfoot 7-8 mm (males) and 7-9 mm (females), forearm 35-37 mm (males) and 36-5-38-5 mm (females); weight 3-1-3-6 g (males) and 3-2-4-2 g (females). Tail of the Thumbless Bat extends a little less than two-thirds the length of uropatagium, in which it is completely encased. Intraspecific divergence in measurements of Thumbless Bats in samples from Espirito Santo and the Guianas varied 2:1-2-5%. Zygomatic breadths are 7-3-7-8 mm, and maxillary tooth rows are 4:7-4-8 mm (females). Specific name horrens refers to bristly hair on this bat. Thumbless Bats are small and delicate, with soft, thick, bluish gray to slate-gray fur on dorsum; venteris slightly paler. Height of braincase, including auditory bullae, is much less than distance from frontal angle to most posterior point of occipital region; muzzle and lips nearly simple. Rostrum is short, ¢.50% the length of braincase. Dental formula is 12/3, C 1/1, P 2/3, M 3/3 (x2) = 36; upper incisors are paired, outerslightly smaller than inner; space between two inner incisors and that between outer incisor and canine are distinct; C' is small, and its shaft is about equal in height to the large P% P! is ¢.50% the size of canine and second premolar; lower incisors have trifid cutting edges, forming continuous row between canines; C is as high as P, and P,, which are about equal in size; and P| is ¢.50% the height of canine. Chromosomal complement has 2n = 34 and FN = 62; Gand C-band data have not been published.

Habitat. Humid tropical and subtropical forests in lowlands at elevations of 250-1200 m. Although Thumbless Bats have been associated with caves, they also use other shelters such as buildings (empty or occupied), tunnels, among boulders, hollow logs, and within or under fallen decomposing trees.

Food and Feeding. Thumbless Bats are insectivorous and fly close to the ground, especially in search of moths. Species of Lepidoptera are more abundant in diets than species of Diptera or Coleoptera.

Breeding. In Colombia,five females were caught in September: one gravid, three nongravid, and a young. Fifty-nine males were found on a fallen tree in Costa Rica in May, and there were isolated males in a cavern in Panama in February. In the most comprehensive study of the Thumbless Bat in Brazil, W. Uieda and colleagues in 1980 reported lactating females with young in January-February, and the young were ready to start flying. On an October night, three young (two males and one female) were hanging on a cliff inside a cave in Brazil. Female reproductive system has short, partially bicornuate uterus; while ovaries typically have abundant stromal type intersticial gland tissue. The placenta is discoidal; large vascular channels are hemodichorial, with widely scattered maternal endothelial cells; and smaller vascular channels are endotheliodichorial (somite stage embryo) (light microscopy). There was a developing discoidal chorioallantoic placenta in a female Thumbless Bat captured in a road culvert in the Western Andes Range of Colombia. Although she carried only a somite stage embryo, most maternal endotelial cells had already been eliminated from the larger vascular channels (establishing a hemodichorial condition) but were still common in the smaller channels.

Activity patterns. It often occurs in small groups of 4-10 individuals but has recently been found in large aggregations (e.g. 59 males roosting inside a tree in Costa Rica and 150-250 mixed-gender individuals in a few grottos in Brazil). Thumbless Bats begin to fly at twilight but do not leave their shelters until after dark. Echolocation calls have low-duty cycles, dominated by sounds less than 100 kHz.

Movements, Home range and Social organization. Thumbless Bats are known to cooccur with several other bat species such as the Woolly False Vampire Bat (Chrotopterus auritus), the Common Vampire Bat (Desmodus rotundus), Pallas’s Long-tongued Bat (Glossophaga soricina), Geoffroy’s Tailless Bat (Anoura geoffroyi), Seba’s Short-tailed Bat (Carollia perspicillata), the White-lined Broad-nosed Bat (Platyrrhinus lineatus), the Lesser Dog-like Bat (Peropteryx macrotis), the Hairy-legged Vampire Bat (Diphylla ecaudata), Little Big-eared Bat (Micronycteris megalotis), and the Greater Spear-nosed Bat (Phyllostomus hastatus). Thumbless Bats could be preyed on by carnivorous bats in caves, and remains of Thumbless Bats have been found in stomach contents of the Fringe-lipped Bat (Trachops cirrhosus), the Greater Spear-nosed Bat, and the Woolly False Vampire Bat.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Thumbless Bat is listed as least concern in the Ecuadorian Red Book of Endangered Species but vulnerable in the Brazilian Red Book of Endangered Species. The Thumbless Bat was long considered one of the most rare Neotropical bats, butit has been discovered recently in relatively large aggregations.

Bibliography. Albuja (1999), Badwaik & Rasweiler (2000), Baker & Bradley (2006), Brosset & Charles-Dominique (1991), Duda et al. (2012), Falcao et al. (2015), Fenton, Whitaker et al. (1999), Gardner (2008h), Husson (1962), LaVal & Fitch (1977), Leal et al. (2014), Medina-Fitoria et al. (2015), Miller (1907), Nowak (1994), Portella et al. (2017), Rasweiler & Badwaik (2000), Reid (2009), Reis et al. (2017), Salles et al. (2014), Simmons & Voss (1998), Tirira et al. (2012), Tomes (1856), Uieda et al. (1980).

Figures

Distribution. S Central and N South America from SW Nicaragua (Refugio Bartola), S throughout Costa Rica and Panama to Colombia , Venezuela , Trinidad I, the Guianas, Brazil , E Ecuador , E Peru , and N Bolivia .