I was barely aware of the existence of these salamanders in the years I first became interested in reptiles and amphibians. They do not get a mention in the popular books available in the 1950s and 60s in Britain that were written by Doris M Cochran or Robert Mertens.
About 30 years ago, I was given a few to keep by whom I cannot remember and my records have disappeared. Individuals of one species were beginning to appear on animal dealers’ lists. That species was Bolitoglossa dofleini from Guatemala, Honduras and Belize. At the time there was no commonly used name. Now IUCN list the following: Alta Verapaz Salamander, Doflein's Mushroomtongue Salamander, Doflein's Salamander, Palm Salamander. It was first described and named by Franz Werner (1867-1939) after Franz Theodor Doflein (1873-1924) who collected the salamander on an expedition to Central America in 1898.
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| Doflein's Salamander One of the ones I tried to keep 30 years ago |
Only years later did I learn that my experience of trying to keep this species was the same as everybody else’s. They appeared to live and feed perfectly well but after a few weeks or months they became lethargic, shed their tails and died. I was annoyed and puzzled that I was unable to keep animals that initially had appeared fit and healthy. Had I got something wrong or did they have some disease that developed with time?
In 2004 a note appeared in Veterinary Record. The authors made the general observation that B. dofleini ‘is generally considered notoriously difficult to keep alive; most imported animals do not survive beyond the first two months after importation’. Three males and two females, recently imported into Belgium, became anorexic and apathetic over a one- to two-week period. Then the hands and feet appeared slightly swollen and began to point upwards. Finally, the tail was shed and the salamanders died 2 to 10 days later.
At this time there was growing realisation that the chytrid fungus, Batrachochytrium dendrobatidis, was having devastating effects on amphibian species throughout the world. The authors of the paper found large numbers of chytrid cells in the cornified layer of the skin all over the body. The origin of the infection could not be determined because the salamanders could have been in contact with other animals in transit to Europe or in the dealer’s premises from which they were obtained.
The suggestion the authors made was that proliferation of the chytrid in the skin might have compromised gaseous exchange in these lungless amphibians. Kidney damage in the form of hyaline droplets was also present but whether this was related to the presence of chytrid was not known. A strange finding in three of the animals was the impaction of the stomach with moss and wooden particles.
I remained puzzled after reading the report in Veterinary Record. While clearly demonstrating the presence of chytridiomycosis, I really could not decide if the animals had died OF or WITH the disease.
Around 1990 the only information I could find indicated that Doflein’s Salamander was found in lowland rainforest. I therefore kept them at temperatures appropriate to that low altitude in Central America. However, I began to wonder if the temperature was too high. Later publications showed an altitude range of 50-1500 metres in the wild including premontane to lower montane wet forest. I did not know where the ones I was given had been collected but if they were from, say, an altitude of 1000 metres, I should have tried keeping them 10°C below that of my simulated lowland tropical environment. I have found suggestions in online fora that people attempting to keep and breed these fascinating amphibians had also tried too high a temperature. In this respect, I read there has been controversy in the past over the altitudinal distribution of the largest of the bolitoglossine salamanders, e.g. B. dofleini, that rely on oxygen uptake through the skin. One view was that large lungless salamanders can only occur at relatively high altitude because the oxygen requirements of the tissues at the higher temperatures of lower altitudes cannot be supplied by the relatively small surface area of the skin. Others have contested that view. However, cutaneous oxygen uptake compromised by the presence of chytrid together with a high environmental temperature in captivity might just have created the perfect patho-physiological storm.
I discovered that from their size the salamanders given to me must all have been females; males are much smaller. Collectors apparently searched the leaf litter and because the females tend to live there while the males prefer to clamber in the trees and bushes it was mostly females that were imported into Europe.
The only success at keeping B. dofleini I have come across is at Fort Worth Zoo. It was reported in 2012 that ten (all females) had been kept for 6 years. On arrival, all had been treated for chytridiomycosis. I have not seen any reference to the environmental temperature in their exhibit. I have been unable to find in the various papers, whether or not those exported for research have been kept successfully for any length of time.
Fortunately, no licences are now issued for the collection of any species of Bolitoglossa (which occur in Central and the north of South America). B. dofleini takes 10-12 years to reach sexual maturity. Thus a breeding population could, by uncontrolled collection of adults, be reduced to dangerously low levels very quickly. IUCN classify the species as Near Threatened.
It does, though, concern me that nobody has a method for breeding any species of Bolitoglossa in captivity—or at least if they have, nothing seems to have been published. The radiation in these salamanders has been so great that they represent 40% of all the tailed amphibians of the world. If—perish the thought—a captive-breeding programme became necessary to ‘lifeboat’ a conservationally important species, there would be very little background knowledge with which to start.
The only consolation of my experience with Herr Doflein’s Salamander was that I did get to see but not to record the remarkable tongue in action. It can be projected up to 31% of body-length in that species in under 20 milliseconds. The maximum velocity achieved was 7 metres per second and the maximum acceleration 4500 metres per second per second. In other words the sticky tongue hits the prey at a speed of 25 km per hour, less than 0.02 seconds after launch. The performance of the paired tongue projector muscles ‘exceeds the greatest maximum instantaneous power output of vertebrate muscle by more than an order of magnitude’.
Here is the video made by Stephen Deban, one of the authors of the paper on the high-power tongue projection in another species of Bolitoglossa, B. franklini:
Deban SM, O’Reilly JC, Dicke U, van Leeuwen JL. 2007. Extremely high-power tongue projection in plethodontid salamanders. Journal of Experimental Biology 210, 655-667. doi:10.1242/jeb.02664
Feder ME, Papenfuss TJ, Wake DB. 1982. Body size and elevation in neotropical salamanders. Copeia 1982, 186-188.
Pasmans F, Zwart P, Hyatt AD. 2004. Chytridiomycosis in the CentraI American bolitoglossine salamander (Bolitoglossus [sic] dofleini). Veterinary Record 153, 153.
Scales JA, O’Donnell MK, Deban SM. 2017. Thermal sensitivity of motor control of muscle-powered versus elastically powered tongue projection in salamanders. Journal of Experimental Biology 220, 938-951. doi:10.1242/jeb.145896
Wake DB, Dresner IG. 1967. Functional morphology and evolution of tail autotomy in salamanders, Journal of Morphology 122, 265-306.
The Toledo Zoo and Aquarium actually had a nice history of keeping Bolitoglossa conanti. Named for their curator of herpetology in the early-mid 1900s. Not only do they keep them alive and well, they breed them.
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