The Marsupial Frog and a Film from the 50s

The Film

When writing recently about ‘Amo’ (Emmanuel Ciprian Amoroso FRS, 1901-1982) and his interest in amphibians I remembered that that he had been involved in making a film about the Marsupial Frog, Gastrotheca sp, which he had kept and studied at the Royal Veterinary College in the 1950s. Amo’s life’s work was studying viviparity, particularly the mammalian placenta. The question was to what extent the mother provides oxygen and nutrients to the young of other vertebrates that are born alive or may, as in amphibians be stored in the body until they are released as tadpoles or young frogs. He was interested in this species because the eggs after fertilization are manoeuvred by the male into the mouth, just above the cloaca, of a backward-facing pouch on the back of the female. The eggs hatch there and the tadpoles grow are released into water at a stage shortly before development of the hind legs.

Amo was very proud of the film. Although the phenomenon of storing eggs in the pouch in these South American frogs was well documented, it is believed this was the first time the whole process had been observed and filmed. I then wondered if the film still existed and where it had been shown.

The first clue was the list of publications in Roger Short’s biographical memoir on Amo. There it is described as ‘1957 Reproductive phenomena in Gastrotheca marsupiata. R. Soc. Conversazione (23 May)’. Notes and Records of the Royal Society (12, 154-159, 1957) provides more information:

The second film was shown by Professor E.C. Amoroso, F.R.S., and Miss J.H Austin, of the Royal Veterinary College, and Dr. J.F.D. Frazer of Charing Cross Hospital, and was concerned with the reproduction methods of the frog, Gastrotheca marsupiatum, which is partially independent of water for its reproductive processes.

I then found that the film had been shown earlier, at a meeting of the Physiological Society at the Royal Veterinary College on 14-15 December 1956 (Journal of Physiology 135, 38P, 1957). There was no other information other than the title and ‘authors’ since the presenters could choose to have their contribution recorded ‘by title only’. The authors were shown as EC Amoroso, J Austin, A Goffin and E Langford. From the acknowledgements I have found that A.R. Goffin was a technician in Amo’s department of Physiology (he is thanked for taking photographs). Miss J.H. Austin in 1960-61 was then on the staff of the department of anatomy, possibly as a lecturer, at the RVC where she is listed in Scientific Research in British Universities and working on ‘development of gastrotheca’. She was not in the 1962-63 volume and I can find no further information on her or on E Langford.

Eventually I found that the film still exists. It is in the collection of the British Film Institute under the title 'Natural history of the large South American pouched tree frog Gastrotheca [originally listed as Gastortheca] marsupiatum'. BFI Identifier 21716. The entry in the catalogue indicates  the original was a 16 mm silent film of a surprisingly long 1500 feet, i.e. 42 minute running time. It is dated as 1955 with a ‘release date’ of 1954 which is unlikely. There is no indication in the BFI catalogue of who made the film or where it was obtained from.

Given the costs of licensing from the BFI I cannot see it ever being digitised or being made available for viewing.

There are lots of videos of Gastrotheca frogs on YouTube but I have not found one that shows the life cycle. In that important respect it seems that Amo’s film is so far unique. Beware though that in searching for ‘marsupial frog’ the best video is one from a BBC series which shows an Australian species, Assa darlingtoni, that has ‘hip pickets’ for its eggs, not a dorsal sac, and is unrelated to Gastrotheca species from South America.

A Publication

In 1957 Amo’s friend and erstwhile collaborator on reproduction and lactation in the Grey Seal (of which stories of their adventures were often related), Leo Harrison Matthews FRS (1901-1986) then Scientific Director at the Zoological Society of London, published a paper in Bulletin de la Société de France entitled, ‘Viviparity in Gastrotheca (Amphibia, Anura) and some considerations on the evolution of viviparity’. I have not read the paper (it falls into that category of too young to be in online archives and too old to be digital) but it clearly covered the same ground and probably the same frogs as the film. It is the only written record covering the breeding of these frogs in London around 1955-56 and has been referred to in later papers in relation to the identity of the frogs (see below).

Amo referred to his work on Gastrotheca in several of his reviews and conference papers but not in a full paper. In 1959 a photograph appeared in the published version of a talk he had given at a Josiah Macy Jr symposium on gestation in Princeton in 1958—again a paper I have been unable to find online. That was reproduced—and is shown below—in another paper, ‘The evolution of viviparity’, published in Proceedings of the Royal Society of Medicine in 1968.

Amo argued that because the eggs of Gastrotheca contain plenty of yolk, the developing young receive oxygen but little if any additional food from the parent. That may be the case in the species he studied but in another, Gastrotheca excubitor, which retains the young throughout the tadpole stage and in which froglets emerge from the pouch, recent evidence suggests the possible transfer of nutrients from the mother to the young through the wall of the pouch. Definitive evidence, though, is still lacking.

Origin of the marsupial frogs in London

Where did Amo get his frogs? Was it via Deryk Frazer who appeared as presenting the film at the Royal Society along with Amo and Austin? A clue exists in an article written by Bob Bustard for The Aquarist in 1958; he wrote:

…An example of this is Gastrotheca marsupiatum, appropriately called the pouched tree frog. I imported this frog into Britain for the first time in 1955, and it has become remarkably popular among vivarium keepers already. This is possibly because it does so well at about 65°F and will breed readily in a small indoor vivarium.

My bet is that the frogs at the Royal Veterinary College came directly or indirectly from Bob Bustard.

A paper also appeared in British Journal of Herpetology describing the breeding in captivity of ‘Gastrotheca marsupiatum’ in 1957 by a J. Walker. I have not seen this paper but my guess it describes animals obtained from Bob Bustard also.

Marsupial frogs were kept in UK throughout the 1980s and early 1990s at least. I do not know if they were newly imported or had been bred in captivity, or indeed were descendants of those imported by Bob Bustard in 1955. Gillett records captive-bred individuals for sale around 1957 and I knew of somebody with a pair in the early 1990s

Which species of frog?

The frogs kept and bred in Britain and in continental Europe in the 1950s and later were all called Gastrotheca marsupiatum or Gastrotheca marsupiata. Before moving on it is worth noting that the currently accepted name is G. marsupiata was that coined by Duméril and Bibron in 1841. The same species was called Nototrema marsupiatum by Günther in 1859. G. marsupiatum appears to have been mistakenly used as Gastrotheca came to replace Nototrema; there may also have been a little discussion over the gender of the specific name matching that of the genus.

But that is by the by. During the 1970s doubt was thrown on the identity of the frogs studied in the 1950s and beyond as G. marsupiata, notably by Eugenia M del Pino in 1975 and by William Duellman and Scott Maness in 1980. The latter listed a number of papers on the reproductive habits of, supposedly, G. marsupiata. That included the paper by Harrison Matthews and, therefore, by implication those in Amo’s film, although by then awareness of the existence of the film seems to have been lost. ‘All those works in which the origin of the specimens was given cite Quito, Ecuador’, Duellman and Scott wrote, continuing, ‘G. marsupiata does not occur north of Central Peru; the Ecuadorian frogs formerly associated with that species are G. riobambae’. As a result of this statement, the animals in captivity became to be referred to as G. riobambae. That view still obtains: captive-bred animals in the USA, Britain and continental Europe are listed as Gastrotheca riobambae—the Andean Marsupial Frog.

What I do not know is where the frogs Amo used for his film were originally imported from and if Duellman was correct in assuming that the frogs in captivity around and after that time were G. riobambae rather than G. marsupiata.

This is the first photograph of a marsupial frog I remember seeing. It is from Doris Cochran's Living Amphibians of the World, published in 1961 by Hamish Hamilton.
The photographer was the American, John H. Tashjian. Also in that volume were black-and-white photographs by Wilhelm Hoppe. All are captioned G. marsupiata. Are the photographs of G. marsupiata or G. riobambae?

This discussion serves to illustrate the value of ‘voucher specimens’ in research and captive-breeding projects. The same consideration applies to photographs since it is very difficult to know whether the animals has been correctly identified, especially those in captivity. With preserved specimens there would be no doubt about which species was being studied or bred. Does anybody have any preserved specimens from these early days of breeding marsupial frogs?

I will return to marsupial frogs in a future article, because their reproductive biology is so fascinating and because their storage of eggs and tadpoles presents physiological challenges that require further study, not the least of which is how the female’s own young avoid the fate of being rejected as non-self while being held in intimate contact with the mother’s body, a biological problem that haunted Amo and one which drove his interest not only in mammals but in reptiles, amphibians and fish.

I found this photograph of the meeting at which Amo (2nd right, front row) talked about marsupial frogs.
It is from the website on placentation by the late Kurt Benirschke (1924-2018)

For those seeking further information:

Amoroso EC. 1968. The evolution of viviparity. Proceedings of the Royal Society of Medicine 61, 1188-1200.

Bustard HR. 1958. Tree frogs. Aquarist and Pondkeeper 23 (4, July 1958), 81-82.

Duellman WE, Maness SJ. 1980. The reproductive behavior of some hylid marsupial frogs. Journal of Herpetology 14, 213-222.

Gillett L. 1995. The good old/bad old days. A survey of reptile and amphibian species traded during the period 1948-1957. British Herpetological Society Bulletin 1995 (52), 26-29.

Kirk BR. 1985. Observations on the breeding of the marsupial frog, Gastrotheca marsupiata. British Herpetological Society Bulletin 1985 (14), 22-24.

Matthews LH. 1957. Viviparity in Gastrotheca (Amphibia, Anura) and some considerations on the evolution of viviparity. Bulletin de la Société de France 82, 317-320.

Pino EM del, Galarza ML, Albuja CM de, Humphries AA. 1975. The maternal pouch and development in the marsupial frog Gastrotheca riobambae (Fowler). Biological Bulletin 149, 480-491.

Warne RW, Catenazzi A. 2016 Pouch brooding marsupial frogs transfer nutrients to developing embryos. Biology Letters 12: 20160673. http://dx.doi.org/10.1098/rsbl.2016.0673