Phyllostomus discolor
Pale spear-nosed bat
Description:
Phyllostomus discolor is known to be one of the smallest species of the genus
(Redford and Eisenberg 1999). Its coloration is dark brown to tan with white tips and
short, soft pelage. P. discolor is stout-bodied and has a short tail that pierces the tail
membrane. The tail length ranges from 10-25mm (Norwalk 1999).
P. discolor has an average forearm length of about 61mm. In males, the head and
body length averages 83.6mm and the average weight is 38.2g. Females have an average
head and body length of 84.2mm and an average weight of 35.4g. (Redford and
Eisenberg 1999)
The dental formula of Phyllostomus discolor is as follows: 2/2, 1/1, 2/2, 3/3=32
(Redford and Eisenberg 1992). It has a long and narrow muzzle, a noseleaf, and widely
separated ears. Many species of this genera are polymorphic (absent or one vibrissa), in
P. discolor the interramal vibrissae are absent (Wetterer et al 2000). The lower lip has a
V-shaped groove edged with wartlike protuberances (Nowak 1999).
Geographic Range:
The pale spear-nosed bat occurs from southern Mexico south to southeastern
Brazil, Peru, and northern Argentina (Redford and Eisenberg 1999). It has also been
recorded in eastern Paraguay (Redford and Eisenberg 1992).
Koopman (1982) recognizes a series of faunal provinces for phyllostomid bats in
South America. The provinces recognized by Koopman for P. discolor are: Eastern
Brazilian highland and coast, Amazon Basin, Northern coast and islands, Pacific coast of
Columbia, Ecuador, and extreme northwestern Peru, and Middle America (Figure 1).
Figure 1. Distribution of Phyllostomus discolor in South America (Koopman 1982).
Ontogeny and Reproduction:
Phyllostomus discolor may have a sex ratio of one male to twelve females in
breeding roosts, suggesting harem formation (Redford and Eisenberg 1999). This species
may be acyclic or a continuous breeder in some areas. In Costa Rica, it could be
monoestrous (one reproductive bout per year) (Nowak 1999).
Ecology and Behavior:
P. discolor is found in mature and secondary rainforest, gardens and plantations,
gallery forest, dry forest, and cloud forest (Emmons 1990). Most specimens taken in
Venezuela were below an elevation of 500m (Redford and Eisenberg 1999).
Phyllostomus discolor roosts in groups of 25 in hollow tree trunks (Redford and
Eisenberg 1999). Emmons (1990) found that several P. discolor fly single file to forage.
Neuweiler (2000) also found that P. discolor, depending on food availability, will go in
groups of 2-15 individuals to visit flowers and fruit bearing trees. Phyllostomus discolor
is known to mainly eat fruit, pollen, nectar, and insects (Nowak 1999).
Remarks:
Most species in the Subfamily Phyllostominae retain the tail and a well-developed
uropatagium, but others show tail reduction and varying degrees of reduction of the
uropatagium. Small phyllostomids are unable to maintain a constant body temperature in
extreme cold. The New World phyllostomid bats are convergent with patterns shown by
the Pteropodidae with their relatively large brains. (Redford and Eisenberg 1992)
The Phyllostomus genus is found to be omnivorous, but captive P. discolor is
known to feed on fruit and to refuse meat (Nowak 1999). In Phyllostomus, pelage is
clearly differentiated into fine wavy under hairs and thicker, straighter longer over hairs
(Wetterer et al 2000). The inferior border of the horseshoe is defined by a thin, free flap
of skin in many phyllostomines such as Phyllostomus (Wetterer et al 2000).
Neuweiler (2000) found in eight mother-infant pairs of P. discolor, each mother’s
directive calls were distinctly different, and the isolation calls of the young gradually
adapted to the time-frequency structure of the mothers call.
There is a need for conservation of mammalian diversity on the extensive
drylands of southern South America as they harbor more endemic species, genera, and
families than the Amazon Basin. In both central and southern South America, human
land-use practices have caused considerable habitat fragmentation and desertification,
which may have affected distributional limits of some mammals. There is heightened
concern about the status of the bat fauna in arid portions of the southern cone from
desertification and throughout Paraguay because of increased economic development
(Willeg et al 2000).
Literature Cited:
Emmons, L. H. 1990. Neotropical Rainforest Mammals, a field guide. The University
of Chicago Press, Chicago, Illinois. 58-59.
Koopman, K. F. 1982. Biogeography of the bats of South America. Pages 273-302, in
Mammalian biology in South America (M. A. Mares and H. H. Genoways, eds.).
Special Publications Series, Pymatuning Laboratory of Ecology, University of
Pittsburgh 6: 1-539.
Koopman, K. F. 1993. Order Chiroptera. Pages 137-241, in Mammalian species of the
world: a taxonomic and geographic reference (D. E. Wilson and D. M. Reeder,
eds.). Smithsonian Institution Press, Washington, D.C.
Neuweiler, G. The Biology of Bats. 2000. Oxford University Press, New York. 258,
275-276.
Nowak, R. M. Walker’s Mammals of the World. 6th Edition, Volume 2. 1999. John
Hopkins University Press. 362-364.
Redford, K. H. and J. F. Eisenberg. Mammals of the Neotropics: the southern cone.
Volume 2: Chile, Argentina, Uruguay, Paraguay. 1992. The University of
Chicago Press, Chicago, Illinois.
Wetterer, A. L., M. V. Rockman, and N. B. Simmons. 2000. Phylogeny of Phyllostomid
bats (Mammalia: Chiroptera): data from diverse morphological systems, sex
chromosomes, and restriction site. Bulletin of the American Museum of Natural
History Number 248: 1-200.
Willeg, M. R., S. J. Presley, R. D. Owen, and C. Lopez-Gonzalez. 2000. Composition
and structure of bat assemblages in Paraguay: a subtropical-temperate interface.
Journal of Mammalogy 81: 386-401.
Reference written by Aimee Wiese, Biology 378 (Mammalogy), University of Wisconsin –
Stevens Point. Edited by Christopher Yahnke. Page last updated August 15, 2005.