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.
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.