AMPHIBIAWEB
Bolitoglossa occidentalis
Southern Banana Salamander
Subgenus: Nanotriton
family: Plethodontidae
subfamily: Hemidactyliinae

© 2014 Dr. Joachim Nerz (1 of 21)
Conservation Status (definitions)
IUCN (Red List) Status Least Concern (LC)
CITES No CITES Listing
Other International Status None
National Status None
Regional Status Protected by the Mexican Government (category Pr)

 

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Description
Bolitoglossa occidentalis has a snout-to-vent length ranging from 28 – 41 millimeters, with a mean snout-to-vent length of 35.3 millimeters. It has a relatively flat head that is wider than its body. The skin on its head has rudimentary indentations, and the length of its eye is about the same as the length of its snout. The rear part of its eyelids end in a diagonal fold, and there is a groove that starts from the eye and runs down its back. It has grooves on its throat that go a short distance up its neck. The skin on its neck and back is smooth, whereas the skin on its sides is wrinkled. Its body is relatively short, and it has 13 costal grooves which are very faint and do not reach the ventral side. Its digits are fully webbed, and it lacks subdigital pads. The ratio of its tail length to its snout-to-vent length is 0.80 +/- 0.2mm, and it has trace lateral grooves that run down its tail (Alberch and Alberch 1981, Alberch 1983, Green and Alberch 1981, Larson 1983, Taylor 1941).

Bolitoglossa occidentalis individuals are characterized by small body size, fully webbed hands and feet, fusion of the tarsals and carpals, the absence of prefrontal bones, the reduction of phalangeal elements, a relatively short tail, and a reduction in skull ossification (Alberch and Alberch 1981).

The prefrontal bone does not form in Bolitoglossa occidentalis (smaller size permits this), unlike in related species, B. rostrata and B. subpalmata. Similarly, the third phalanx of the fourth digit does not exist in Bolitoglossa occidentalis as it does the two previously mentioned species. The tail of B. occidentalis appears shorter than in other Bolitoglossa because it has a relatively bulkier body (Alberch and Alberch 1981).

The allometric patterns in the rate of increase in foot surface area compared to body weight are analogous for the three species B. rostrata, B. subpalmata and B. occidentalis, despite major variation in foot shape. However, truncation occurs early in development of B. occidentalis, accounting for the webbed condition found in this species (Alberch and Alberch 1981).

In life, the dorsal coloration can range from gray to dull brown with dark lavender-brown markings present above the eyes and crossing the neck. The lower half of its body and its tail are streaked with cream and light brown spots. The sides of the head, body and tail region are the same as dorsal coloration. The ventral surfaces are generally lighter in color, and may be punctuated by tiny spots of pigment (Taylor 1941).

Color patterns vary considerably, however lines above the eyes and neck are typically distinct. The backsides of the neck and base of tail are generally lighter than the rest of the back. Some individuals may have a darker vent with noticeably lighter flecks (Taylor 1941).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Guatemala, Mexico

 

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This species has been found in Mexico, Guatemala, and Honduras, and resides along the Pacific versant of Mesoamerica to the Vulcan Atitlan in southern central Guatemala. Local distributions in Guatemala and Mexico include San Marcos and Chiapas, respectively, with an elevation of about 600 – 1050 m asl. Its predicted existence in Comayagua, Honduras is based off of the discovery of one specimen, so its occurrence there now is unlikely. They occur at altitudes between 10 – 1,600 m asl (Acevedo et al 2008, Feder 1983, Papenfuss 1983).

Life History, Abundance, Activity, and Special Behaviors
Bolitoglossa occidentalis are direct developers that rely on chemoreception for attracting potential mates. Reproductive activity occurs year-round in females and males, as a result this species is spermatogenetic throughout the year. Males have a large variation in testicular composition, and they have primary spermatocytes at the anterior portion of the testes. Spermatocyte density decreases in a linear pattern from anterior to posterior. The density of primary spermatocytes varies with temperature, typically from March through July. Changes in the testes occur between May and June. Females deposit eggs in decaying logs, under rocks, and in bromeliads (Chan 2003, Taylor 1941).

They live in lowland wet forest with high seasonality, residing in an arboreal microhabitat of bromeliads in the outermost leaves of banana plants and pine-oak forests. Bolitoglossa occidentalis occupies bromeliads in higher densities during the dry season due to the seasonally dry climate. The mean temperature of their habitat hovers from around 28 – 30 degrees Celsius (Chan 2003, Feder 1983, Taylor 1941).

Other larger vertebrates prey on them, and although they are not toxic, they use tail autotomy as a defense mechanism (Shaffer 1978).

Trends and Threats
Densities of neotropical, arboreal salamanders have declined in the last several years. Individuals from Guatemalan populations tested positive for chytrid fungus, but the implications of this are unknown (Chan 2003, Papenfuss 1983).

Relation to Humans
N/A

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Disease
Climate change, increased UVB or increased sensitivity to it, etc.

Comments
The species authority is: Taylor, E. H. 1941. New Amphibians From the Hobart M. Smith Mexican Collections. The University of Kansas Science Bulletin 27:141-167.

Bolitoglossa occidentalis is a sister species to B. rufescens; both are characterized by an inflated nasal region, the absence of folds under the tongue, and webbed hands and feet (caused by the absence of the gene that causes apoptosis in salamander toes). However, they do differ somewhat in general coloration and the presence of maxillary teeth (Taylor 1941).

“Bolito” is derived from the Latin term “boletus” meaning mushroom, ultimately stemming from the ancient Greek word “bolos” -- a lump or clod. “Glossa” stems from the Greek word “glosso”, meaning tongue. “Occidentalis” is a Latin adjective mean “western” (Online Etymology Dictionary).

The partial fusion of the ascending processes of the premaxilla was observed in one specimen of Bolitoglossa occidentalis in 1983. This type of fusion is not typical for Bolitoglossa, but is present in other plethodontid genera. It is unable to move its digits independently, and instead the entire foot acts as one fused “plate” (Alberch 1983, Alberch and Alberch 1981).

References

Acevedo, M., Wake, D., Rovito, S., Papenfuss, T., Vasquez, C., Castaneda, F. 2008. Bolitoglossa occidentalis. The IUCN Red List of Threatened Species. Version 2014.3. www.iucnredlist.org. Downloaded on 14 January 2015.

Alberch, P. (1983). ''Morphological variation in the neotropical salamander genus Bolitoglossa.'' Evolution , 37, 906-919.

Alberch, P., Alberch, J. 1981. Heterochronic Mechanisms of Morphological Diversification and Evolutionary Change in the Neotropical Salamander, Bolitoglossa occidentalis (Amphibia: Plethodontidae). Journal of Morphology 167.2: 249-264.

Chan, L. M. 2003. Seasonality, Microhabitat and Cryptic Variation in Tropical Salamander Reproductive Cycles. Biological Journal of the Linnean Society 78.4: 489-496.

Feder, M.E. (1982). ''Thermal ecology of the Neotropical lungless salamanders (Amphibia: Plethodontidae); Environmental temperatures and behavioral responses.'' Ecology, 63(6), 1665-1674.

Green, D.M., and P. Alberch (1981). ''Interdigital webbing and skin morphology in the Neotropical salamander genus Bolitoglossa (Amphibia, Plethodontidae). .'' Journal of Morphology , (170), 273-282.

Harper, D. 2015. Online Etymology Dictionary. www.etymonline.com. Downloaded on 15 Feb. 2015.

Larson, A. 1983. ''A Molecular Phylogenetic Perspective on the Origins of a Lowland Tropical Salamander Fauna I. Phylogenetic Inferences from Protein Comparisons.'' Herpetologica 39.2: 85-99.

Papenfuss, T. J., Wake, D. B., Adler, K. 1983. Salamanders of the Genus Bolitoglossa from the Sierra Madre Del Sur of Southern Mexico. Journal of Herpetology 17.4: 295-307.

Shaffer, H. B. 1978. ''Relative Predation Pressure on Salamanders (Caudata: Plethodontidae) along an Altitudinal Transect in Guatemala.'' Copeia 1978.2: 268.

Taylor, E. H. (1941). ''New amphibians from the Hobart M. Smith Mexican collections.'' University of Kansas Science Bulletin, 27, 141-167.



Written by Hanna Kirkorian, Kelsey Nelson (hkirkorian AT ucdavis.edu, kelnelson AT ucdavis.edu), University of California, Davis
First submitted 2015-06-10
Edited by Gordon Lau (2015-06-22)

Species Account Citation: AmphibiaWeb 2015 Bolitoglossa occidentalis: Southern Banana Salamander <http://amphibiaweb.org/species/3996> University of California, Berkeley, CA, USA. Accessed Oct 20, 2017.



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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 20 Oct 2017.

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