The Moral of this Story: Do Not Keep Frogs in the Bedroom if You Want to Sleep

Writing about Edward J. Bles and his breeding of Xenopus laevis in Cambridge and Glasgow, I was reminded that more than 55 years ago I received from Kenya a small batch of Xenopus. Over the years I realised they could not have been the species the man who sent them described them as. My frogs were collected in an around Nairobi and he thought they were Müller’s Clawed Frog, Xenopus muelleri. However, with the benefit over 50 years of research, more observations and the description of new or resurrected species lumped into X. laevis, it is now clear that this species does not occur around Nairobi. Local naturalists described finding X. laevis in that area in the 1960s and 70s. However, present distribution maps show two species might be encountered around Nairobi: the Marsabit Clawed Frog, X. borealis and, less commonly, the Mwanza or Lake Victoria Clawed Frog, X. victorianus. Both of these have been included in X. laevis in the past. But which ones were sent to me?

Xenopus borealis
from here

Comparing the rather poor descriptions and photographs available on internet searches, my best guess is that they were X. borealis. I remember that they were smaller and darker in colour than X. laevis, with darker markings on the back. The call of both X. victorianus and X. borealis appears to be different from X. laevis, the latter likened to the winding of a watch. One keeper of X. borealis noted that their call is like ping pong balls hitting the bat. I haven’t been able to find a sound recording of that species on internet searches. However, I did find a recording of X. victorianus, and that was very much as I remembered it. I find that I described it in print as ‘hitting an empty cup with a tea spoon’.

The reason I have a vivid memory of the call is that I installed a small group in a tank in my room in Sheffield. Sustained sleep was impossible. Shortly after the light went out, several started calling. It was impossible to see which individuals were responsible since they produce their call without an external sign of movement. The loud calling went on night after night—matching the reports that the call of X. borealis is louder than X. laevis—so that by the end of the week the frogs were moved to pastures new.

Little did we know in the 1960s, of course, that the movement of Xenopus around the world for pregnancy tests, for developmental biology research and for amphibian keepers would be implicated in the spread of the chytrid fungal disease of amphibians, Batrachochytrium dendrobatidis. throughout the world, causing devastation to populations of some species that lack resistance. I find all sorts and ‘ifs’ and ‘buts’ about the chytrid disease story but I do note with interest that the fungus has recently been detected in preserved specimens of X. borealis collected in Kenya in 1934.