Glossophaga soricina - Pallas’ Long-tongued Bat​

Physical Description:

Glossophaga soricina is medium sized when compared to the rest of the genus. G. soricina has a large procumbent first upper incisor. The lower incisors are relatively large which fill the gap between the canines. The premaxillae elongate anteriorly; the pterygoid “wings” are usually present and are usually well developed. The presphenoid ridge is evident and prominent throughout. A combination of these features can help distinguish G. soricina from the rest of the genus Glossophaga (Alverez 1991). The dental formula of Glossophaga soricina is as follows: I 2/2, C 1/1, P 2/3, M 3/3= 34. The incisors are well developed and the molars “retain much of the primitive insectivorous ectoloph pattern.” The coat of G. soricina is a shade of black dorsally and a buff color ventrally. Palla’s long-tongued bat has a stomach that is larger and more specialized than any other phyllostomine. G. soricina has an ear morphology which is consistent with its feeding behavior by having no extreme modifications. G. soricina and other Glossophagines have short wings when compared to other phyllostomids (Alverez 1991); this may be due to their behavior which includes hovering while feeding on nectar and short flights because of a relatively small home range. 

Distribution:

Glossophaga soricina is found from Mexico, west in Sonora and east in Tamaulipas, to South America from Paraguay to northern Argentina. G. soricina has also been documented in Jamaica, the Tres Marias Islands, and other islands adjacent to the northern areas of South America. G. soricina frequents a wide variety of habitats, including arid-subtropical thorn forest, tropical rainforests, and savannas. G. soricina can be found up to 2,600 m, but is usually found in lowland areas (Alverez 1991). There are five subspecies of Glossophaga soricina which include G. s. antillarum, G. s. handleyi, G. s. mutica, G. s. soricina, and G. s. valens. G. s. antillarum is limited to Jamaica. G. s. handleyi is found in western and eastern Mexico, except for most of the Mexican Plateau, permeating south through Central America to the northwestern areas of South America. G. s. mutica is constrained to the Tres Marias Islands. G. s. soricina inhabits most of the South American range of the species east of the Andes Mountains, as well as Trinidad and Isla Margarita (Alvarez 1991).

Ontogeny and Reproduction:

Glossophaga soricina has a reproductive pattern and development that was studied extensively during the 1970’s. The ovulation of G. soricina is spontaneous and typically only one ovum is released per cycle. Ovulation usually alternates between the two ovaries. Ovulation and menstruation usually take place around the same time. After fertilization occurs, the embryo has reached the two-cell stage of development by day 2 or 3. The eight-cell stage happens within 5- 7 days. It divides to the 32-cell stage by day 8, and reaches the blastocyst stage by the 10th day. The blastocyst is implanted in the uterotubal junction during days 12- 14(Alverez 1991). Alverez states, “The occurrence of menstruation and interstitial implantation suggests that G. soricina might possess considerable potential for development as an animal model in human reproductive research.”

            Alverez accounts that early reproductive research efforts suggested that G. soricina was monoestrous (Hamlett 1934), but more recent work has shown aseasonal ployestry in Mexico (Cockrum 1955) and Columbia (Tamsitt 1966), and bimodal polyestry in Panama (Fleming 1973), Costa Rica (Heithaus et al. 1975), and northern Brazil (Willig 1985). G. soricina is polyestrous in captivity and has a reproductive cycle of 22- 26 days (Rasweiler 1972). Also, research shows that copulation does not precede ovulation, but most likely happens at the same time (Hamlett 1935b).

Ecology and Behavior:

Glossophaga soricina inhabits caves, tunnels, abandoned mines, hollow trees and logs, buildings, culverts, and beneath bridges. Their colonies usually host both sexes, but the females and their offspring form maternity colonies during certain times of the year. G. soricina roosts in association with many different types of bats in these dwellings. Alverez states, “In the Peruvian Andes, 60% of the roosting sites of G. soricina were shared with Carollia perspicillata…this suggests a beneficial association between the two kinds of bats by reducing the costs of thermoregulation.” There has been data from recaptures in Costa Rica and Mexico which would suggest that G. soricina inhabits a small home range as compared to larger species that were in the same area; this could point to a possible relationship between their body size and their home range (Alverez 1991). The diet of G. soricina is mainly nectar and pollen from April to June, and then it prefers to feed exclusively on insects. G. soricina is host to several bacterial, mycotic, protozoan, and viral diseases, two of which are yellow fever in Brazil and rabies in Mexico (Alverez 1991).

            Glossophaga soricina has a night activity pattern that is bimodal; its peak activity time is right after dark and right before dawn. G. soricina can feed on the flowers of gourd trees by hovering over them or landing on them, which is most common method. They also help pollinate because the pollen sticks to their wings, body, and head and is transferred between plants. G. soricina displays territoriality toward other bats by flying straight at them on a “collision course.” The intruding bats, for the most part, leave immediately being pursued by the territorial bat. These aggressive displays increase as food becomes harder to find. Research also showed that females shared their feeding areas with their immature offspring.

Remarks:

Except for primates, most mammals have dichromatic vision, which limits color perception. Only a short time ago ultraviolet vision was found to be possessed by mammals, in certain marsupials and rodents. Bats mainly use echolocation, but also use color vision sometimes. Recently, in research done by Winter, Lopez, and Von Helversen they showed that Glossophaga soricina is color-blind but sensitive to ultraviolet light readings down to 310nm. They discovered that the excitation of the beta-band of the visual pigment is thought to cause ultraviolet sensitivity (Winter 2003). Winter states, “This is a mechanism for ultraviolet vision that has not previously been demonstrated in intact mammalian visual systems.” The use of ultraviolet vision is thought to help G. soricina feed during these low light conditions by finding certain flowers that emit the ultraviolet light within their vision spectrum. 

Literature Cited:

Alverez, J., Willig, M.R., Jones, J. K., Jr., Webster, D. W.  Mammalian Species, No.379: 1-7. November 1991.   

Cockrum, E.L., Reproduction in North American bats. Transactions of the Kansas Academy of Science, 58:487-511. 1955.   

Fleming, T.H., The reproductive cycles of three species of opossums and other mammals in the Panama Canal Zone. Journal of Mammalogy, 54:439-455. 1973.

Hamlett, G.W.D. Uterine bleeding in a bat, Glossophaga soricina. Anatomical Record, 60:9-13. 1934

          -- Breeding habits of the phyllostomatid bats. Journal of Mammalogy, 16:146-147. 1935b.

Heithaus, E.R., T. H. Fleming, and P.A. Opler. Foraging patterns and resource utilization in seven species of bats in a seasonal tropical forest. Ecology, 56:841-854. 1975.

Rasweiler, J.J., IV. Reproduction in the long-tongued bat, Glossophaga soricina. I. Pre-implantation development and histology of the oviduct. Journal of Reproduction and Fertility, 31:249-262. 1972.

Tamsitt, J.R. Altitudinal distribution, ecology, and general life history of bats in the Andes of Columbia. American Philosophical Society Yearbook, pp. 372-373. 1966.

Willig, M.R. Composition, microgeographic variation, and sexual dimorphism in Caatingas and Cerrado bat communities from Northeast Brazil. Bulletin of the Carnegie Museum of Natural History, 23:1-131. 1983.

Winter,Y., Lopez, J., Von Helversen, O., Ultraviolet vision in a bat. Nature, 425:612-614. October 2003. doi:10.1038/nature01971.

Reference written by Richard Ash, Biology 378 (Mammalogy), University of Wisconsin – Stevens Point.  Edited by Chris Yahnke.  Page last updated August 8, 2005.