by Greg Mayer
As an Everton supporter, I am loath to praise anything Mancunian, but Andrew Johnson, a Manchester zoology graduate, has a marvelous website on the Amphibians of Borneo, which was brought to my attention by Matthew (yet another praiseworthy Mancunian).
The site contains excellent photographs of many species of Bornean frogs. What struck me most is the resemblance of many of the depicted species to Central American frogs, especially the Costa Rican ones with which I am most familiar. Our toad friend above reminds me of the gracile-limbed Central American toads of the genus Atelopus. (Superb photos of the various Costa Rican frogs mentioned can be found in Jay Savage’s magisterial The Amphibians and Reptiles of Costa Rica [see references] and at Costa Rican Frogs, a site I just discovered.). The following one is a more typical-looking toad, resembling various Central American Bufo.
The following species resembles the Central American toad Bufo haematiticus in its cryptic forest-floor dress, but is in fact not a true toad, but a member of a different family.
The resemblances between the Bornean and Central American frogs is a mixture of convergence (in this case, adaptation to the varied niches of tropical rain forest) and common ancestry (in some cases, a toad is a toad is a toad). Convergence is indicated when similar species are in different families, but it’s also possible within families. Both American Atelopus and Bornean Ansonia are members of the family Bufonidae (true toads), but their gracile form may have evolved independently from more squat ancestors (that’s why phylogenetic studies are so important for elucidating evolutionary phenomena– we need to know who’s related to who, and what the likely ancestral conditions were).
Here are several other of my favorites. The first resembles Central American Leptodactylus, especially pentadactylus.
Our friend above is named in honor of my esteemed colleague Robert Inger of the Field Museum, the dean of Bornean amphibian studies (see references below). The following species, in the same genus, Limnonectes, resembles various Central American Eleutherodactylus, a very species-rich genus with more than 40 Costa Rican species.
We’ll finish with some treefrogs, none of which are in the “true” treefrog family, Hylidae (which has many genera and species in Central America), but rather the Old World Rhacophoridae. The first resembles some of the the Central American Smilisca.
The next resembles various Hyla.
And finally, a flying (actually gliding) frog; note the large webs. Some Costa Rican hylid treefrogs of the genus Agalychnis are capable of gliding, too.
A more academic site devoted to Bornean frogs, also beautifully illustrated and with a great range of useful information, is Frogs of Borneo, by Alexander Haas and Indraneil Das. The American Museum of Natural History is currently hosting a traveling exhibition entitled Frogs: a Chorus of Colors, featuring live (not preserved) frogs, which I saw when it was at the Milwaukee Public Museum, and is worth seeing if you’re in the New York area.
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Behler, J. and D. Behler. 2005. Frogs: A Chorus of Colors. Sterling Publishing, New York. (book to accompany the exhibition)
Inger, R.F. 1966. The systematics and zoogeography of the amphibia of Borneo. Fieldiana Zoology 52:1-402. (downloadable as pdf)
Inger, R.F. and R.B. Stuebing. 2005. A Field Guide to the Frogs of Borneo. 2nd ed. Natural History Publications (Borneo), Kota Kinabalu, Sabah, Malaysia. (available here)
Inger, R.F. and F.L. Tan. 1996. Checklist of the frogs of Borneo. Raffles Bulletin of Zoology 44(2): 551-574. (pdf)
Savage, J.M. 2002. The Amphibians and Reptiles of Costa Rica | A Herpetofauna between Two Continents, between Two Seas. University of Chicago Press, Chicago.
I was going to ask are the gliding frogs all related or have they evolved after the break up of Pangaea then thought – ‘look it up you twit!’ – and blow me, evolution works in familiar ways – they evolved gliding independently. Thanks Greg!
Here we go again. It’s a frog, it lives in a tree, but it’s not a “true” treefrog?
“True” obviously means something different to taxonomists than it does to ordinary mortals.
The problem is not so much taxonomic as it is linguistic. There is not a very great diversity of members of the order Anura in Europe, and especially in Britain. Thus, the English language does not contain enough vernacular words for all the varied types of anurans that occur throughout the world. Britain has only two sorts of anurans, members of the genus Rana (1 species) and Bufo (2 species), and these received the English common names “frogs” and “toads” respectively. Nick Arnold expresses it well in his Reptiles and Amphibians of Europe (Princeton Univ. Press, 2002):
The terms “true frog” and “true toad” are used to differentiate the two families to which the original English frog and toad apply, the Ranidae and Bufonidae, respectively (Arnold uses “Typical” instead of true). “True treefrogs” are members of the family Hylidae which contains the genus Hyla, to which the European treefrog (found in France, but not Britain) belongs.
If we spoke a language which had developed in an area with many distinctive anurans, we’d probably have more words for the many families of anurans, and would not need to use modifiers such as “true” or “spadefoot” or “narrowmouthed” to give vernacular names to them all.
GCM
Actually Greg, the Pool Frog Pelophylax lessonae is I think now considered to be a British native – http://www.herpconstrust.org.uk/animals/pool_frog.htm
but that is quite recent, & I suppose not without arguments against it…
I mean that adds a second ‘native’ species! (There are alien bullfrogs & marsh frogs).
Arnold equivocated a bit about lessonae, suggesting that it was possibly native, but that the native population was wiped out, and current populations are introduced. It’s neat that the site you link to notes that a captive East Anglian lessonae survived until 1999. I suppose that the question is whether the East Anglian frogs might have been an early introduction. (Who knows what the Angles, Saxons, Jutes, and Danes had in their ships, not to mention the Romans and Britons?) The fossil record might help decide. I don’t know of a good compilation for British fossil herps, but there’s a nice book on The History of British Mammals by D.W. Yalden that reviews the fossil evidence for the origin, including by introduction, of British mammals. If you like that sort of thing (I do!) it’s well worth a read.
But I’m glad to have two native British frogs, rather than just one. (It’s a nice balance with the two native toads.)
GCM
Wow – looks like a great book – thanks! [I am a bit biased, being a British mammal myself…]
If introduced my money is on the Romans – they probably introduced the edible snail and fallow deer…
#4 looks tasty but I have no idea if it’s edible beyond the truism that everything is edible, once.
#3 hides its functional features with flat overhanging surfaces facing up — like Tacit Blue hides its functional features with flat overhanging surfaces facing down.
(Subscribing)