Scientists love islands because the processes of evolution on islands are simpler than they are on more complex, much larger continents and thus more easily studied. I have made the point that the islands of Sao Tome and Principe are very poorly known, but what we do know is very exciting. One evolutionary pattern that seems to consistently appear on islands is the phenomenon of gigantism; for some reason certain successful colonizers become very large on islands: for instance, think of the tortoises on the Galapagos Ids. or on Aladabra. There are a number of hypotheses that attempt to explain this phenomenon, but none is particularly compelling; nevertheless, the pattern exists and is very evident on the oceanic Gulf of Guinea Islands. The composite image below illustrates just a few of the giants on Sao Tome and Principe.

Some Island Giants

Think of potted plants for a moment… how large is a begonia? The central plant in this composite image is the largest species in the world, Begonia baccata. It is found only on the island of Sao Tome and reaches 10 meters in height! This particular specimen graces the southern shore of Lagoa Amelia at about 1480 m elevation - my head comes up to about flower level on this old friend (I am 6′ tall); these enormous plants are common at higher levels. The two birds figured are also giants: the yellow one on the right is the world’s largest weaver. Ploceus grandis,. and the one on the left is the world’s largest sunbird, Dreptes thomensis; both endemic to the larger island of Sao Tome. This is a good point at which to mention that island dwarfism is also an observable phenomenon  here as well, and the world’s smallest ibis, the Sao Tome Dwarf Ibis, Bostrychia bocagei is also an endemic.  The other critters in the collage, the frogs and the lizards, are all endemic giants but I will deal with them later. It is important to bear in mind that when we call a species a “giant”, we are describing its size compared to all of its other relatives only; such a species may not appear to be a giant at all, in our eyes.

The Sao Tome Giant Treefrog, Hyperolius thomensis, and I go back a long way; back to when I was writing my doctoral dissertation many years ago. This sapo (as all frogs are called on the islands) is endemic to Sao Tome only and is easily the largest member of its genus (Hyperolius)- females reach lengths of nearly 50 mm.from snout to vent!

Sao Tome Giant Treefrog, Hyperolius thomensis.GG I and GG II - D. Lin

Nearly all of the original material from which this species was described in 1886 was destroyed in the fire in Lisbon.  But I managed to find four remaining specimens, two in Vienna and two at the Natural History Museum in Vienna, allowing me to treat them in my dissertation.  In 1988 and again 1990 more specimens were reported by a Swiss worker, but her published locality data are very general, if not vague, and it turns out that most of the material she worked on was collected by locals at her request prior to her arrival.  During GG I, we visited most of her reported localities, finding nothing until we finally got lucky. Now, I can state that this most flamboyant of treefrogs is currently known for certain from only a single locality!  Our work in GG I, II and III has confirmed that this marvelous critter is known only from higher elevations (above 1000 m), inhabiting the canopy of old secondary or primary growth trees on steep slopes.  And it appears to breed only in the water-filled holes in trees with fluted bark or buttresses.  This is a rarity – in Africa, only 9 other frog species are known to breed in phytotelmata (scientific word for treehole). But it makes sense.  Most frogs lay eggs, which develop into free-swimming, gilled tadpoles, which then metamorphose.  Although there are many fast moving rivers on the steep slopes of Sao Tome, these are far to swift for breeding; still bodies of water simply do not exist. So, H. thomensis has adapted to breeding in ephemeral, rain-filled holes in the trunks of very large trees! All of the other frogs native to the islands utilize slow moving or still water for reproduction.

The tree - J. Clara, GG III

This is the only tree in which we have collected the Sao Tome Giant treefrog.  It is at about 1100 m on a high ridge, and we return each expedition to check its status. Adults are usually present but there are always eggs and tadpoles at different stages of development in the holes.  Tom and Rebecca, our botanists, could not identify this tree – it is simply too tall its see its canopy, and moreover it is festooned with epiphytes.

Frogs and eggs in treeholes -  WE, GG III

Wes Eckerman, our photographer tried to climb it, and then tried to climb an adjacent tree to see if there were more holes, but the tree is just too big in girth to handle; with our friend Jose Clara, we tried to erect a crude ladder to examine a hole farther up the trunk but to no avail.

RCD, GG III

I do not mean to imply that this species is restricted to this tree.  We have heard the species calling at night from high up in the canopy and reasonably certain that it is pretty widespread, at least in the high elevation forests we have visited – I suspect it is present on Sao Tome anywhere the trees are large enough and that. of course.  means upslope above the former Portuguese plantations.  What is different about this single documented tree is that it is the only one whose rain-filled holes are within our reach – there are undoubtedly more holes in many more trees that are too high for us to access.  I am left with the notion that given its restricted range and peculiar breeding biology, the Sao Tome Giant Treefrog is a classic indicator species; its presence means healthy mature forest.  If I were to choose an icon to symbolize the dogged persistence of pockets of nature in the face of man’s depredations and at the same time the attitude, beauty and whimsy of the citizens of Sao Tome and Principe, it would be this gorgeous island giant. Josef, my former student, informs me that he has already seen the name of this species on a price list in the pet trade in Europe.  If you  wonder why I have not described the location of this tree is in more detail, now you know. 

In the last posting, I promised you a picture of the cobra jita of Sao Tome. Here are shots of both island forms, which are currently considered to be the same species.

Sao Tome Jita - RCD, GG I

Principe Jita - WE, GG III

Not only do these critters look different from those on Sao Tome (stripes vs. patterned blotches), they act differently as well. On Sao Tome, cobra jita appears to be strictly nocturnal; during GG I and GG II we easily found them at night by first listening for the loud choruses of oceanic treefrogs (more about them later). So far as we know, the Sao Tome jita largely feeds on these frogs while they are breeding and is strictly nocturnal; to see at least ten of these snakes in a single night under the right conditions is not uncommon.

R. Stoelting, my grad student, with her first Jita - GG I, RCD phot. After our week on Principe, however, I am prepared to say that that jita is diurnal and although we will not know until we check stomachs, I think it feeds on lizards and small rodents. We even located a chorus of treefrogs behind Bombom but failed find a jita, nor did we ever find one during our night hunts. Only time and careful study of morphology nd DNA will tell us how closely related these two island snakes really are.Thanks to Caitlin D. for her generous donation. We are doing what we can!

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We are still on Principe and down to the hard corps: me, Wes and Josef. The mushroom and plant folks, Dennis, Brian, Tom and Rebecca are home in San Francisco by now. So it is time to tell you a little about my own research interests. Cobra Jita is a snake and we have been looking for it all week; in order to explain why, I need to tell you a frog story.

Josef Uyeda on Principe. Weckerphoto GGIII

As I have said, the fact that there are amphibians here at all is astounding; amphibians, along with primary freshwater fish, are among the poorest dispersers across saltwater barriers known. They are the last kinds of critters one would expect to find on an oceanic island…. Think of the Hawaiian Islands and the Galapagos, perhaps the two most intensely studied oceanic archipelagos in the world… no frogs or other amphibians, right? But here on Sao Tome and Principe we have seven amphibian species, one of which is the famous caecilian, Schistometopum thomense. How can this be? How did they get here? More on this later, but one of the keys is time: remember that Sao Tome is at least 15 million years old, and Principe is more than double that, perhaps 31 million years. Hawaii and the Galapagos are but 5 million years max.

During GG I, we collected series of little brown frogs of the genus Phrynobatrachus from various locations on both islands; at the time all of them were considered the same species, P. dispar, originally described from Principe over 100 years ago. In 2005, a bright young intern from Willamette University named Josef Uyeda, spent the summer in my lab studying these preserved specimens and concluded that the frogs were quite different. Josef joined GG II and did a lot of collecting on both islands, recorded calls, did dissections and comparisons of DNA from the critters on both islands. The results are that the two island frogs are VERY different; in fact, there is nearly 21% DNA sequence difference between the two; indicating that they have not interbred in many millions of years, possibly predating the existence of Sao Tome (yet they still look virtually identical!). Moreover the two together appear to be more closely related to East African species than to more nearby West African species, but more on that later. In 2007, Josef, I and Breda Zimkus of Harvard described the Sao Tome brown frogs as a new species, Phrynobatrachus leveleve.

Phrynobatrachus leveleve. Sao Tome. Weckerphoto GGIII

Phrynobatrachus dispar Principe. Weckerphoto GGIII

from Uyeda et al. 2007. Proc. Calif. Acad. Sci. 58

This brings me to cobra jita (pronounced “zheetah” – it means snake slow, as opposed to the other Principe snake, cobra sua sua, which means snake fast!). Here we have the same situation as we had with the small brown frogs, Phrynobatrachus. Jita (more properly known as Lamprophis lineatus bedriagae, or lined house snake) has always been considered to be the same species on both islands. After our frog studies, I am not so sure! They look different – regrettably I will have to post a picture of the Sao Tome form later… didn’t bring one in my zip drive—the Principe form is much more obviously patterned than the Sao Tome snake. During GG I and GG II we got very good samples of the Sao Tome population, but for some reason, only one specimen from Principe.

Lamprophis from Bombom Id, Principe. Weckerphoto GGIII

Lamprophis from Sao Tome. D. Lin photo. GGII

Josef is now a PhD candidate at Oregon State University and joined us a couple of weeks ago in our search for Jita (among other things I will describe later). Snakes, as you probably know, are where you find them… as primary predators, they are never very common but always around, and such has been the case here on Principe. It has taken us six days of trekking around in the forest, turning over logs, etc. to find six snakes. But I am delighted. This is certainly enough now to estimate the genetic distance between the two populations, and given the age of these islands, I will not be surprised at all to learn that they are distinct at the species level.

Josef and I looking for Jita on Bombom Id. Weckerphoto. GGIII

We have learned a lot about this critter. On Sao Tome, Jita is primarily nocturnal while the daylight hours on that island seem to be dominated by the endemic Sao Tome green bush snake, Philothamnus thomensis. This is the situation we would predict using island biogeographic theory—no niche overlap – they both seem to eat frogs and skinks, but at different times. But here on Principe, all of the jitas we have caught have been during the daylight hours, as was the single individual caught during GG II in 2006. Moreover, the green snake of Principe (yes there is a green sua sua here as well, but not related to the Sao Tome species) also seems to be diurnal! They are incredibly fast; we have seen two of them and missed both. So until we can look at stomach contents, we seem to have an ecological mystery.

Me, Josef and Ramos on Bombom Id. Weckerphoto GGIII

Our search has been greatly aided by an amazingly bright local naturalist; Jose Ramos Maria Vital Pires, or Ramos for short. Ramos has led us around this island searching for the elusive jita we have been blown away by his keen perception and observations of the local flora and fauna, and his delightful smile and sense of humor. The thing is everyone knows about this snake, most of the locals are to say the least, not exactly fond of snakes and one referred to as a “house snake” frequently comes a little too close for comfort, as you might imagine. But finding a snake when you are looking for it is entirely different matter. Our first success occurred on Bom Bom Island (not really and island, but sort of). I had just commented that the area Ramos was leading us through was too steep to find a snake, when he began excitedly shouting “snake!” only meters away. Within moments we had bagged our first jita.

There have been some rather ignominious moments for me personally. My two young compadres, Wes and Josef are willing to give me credit for catching but one jita, a dead one. The specimen had, in fact, been killed two hours earlier by a local woman who was delighted to have us remove it from along the road. This morning was the last straw. We had been combing Bom Bom Island again; Josef and Wes had taken a lower route than I and about an hour in, I heard Josef yell that they had caught a snake in the act of ripping a tail off a skink. Well and good, I thought, but where’s mine? So I am walking along, seeing snake food like skinks all over the place, when Wes and Josef come down the trail towards me. We stopped, admired the snake Josef had already bagged and the photos Wes took of it eating its skink tail, all three of us turned around…Josef stooped over and grabbed our largest jita of the expedition, about a foot behind me. I must have stepped right over it a moment beforehand. Perhaps it is not necessary to tell you that there has been much snickering among the younger members of this outfit ever since… Argh.

Josef collecting a jita on Bombom. Weckerphoto GGIII

Nova Cuba, near Santo Antonio, Principe. Weckerphoto GGIII

More anon.

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As I mentioned yesterday, the first two botanists to join one our GG expeditions are Dr. Tom Daniels of CAS Botany Department and one of his graduate students, Rebecca Wenk. Both are specialists on a large family of tropical herbs called the Acanthaceae. Can’t give you a common name, sorry.

Rebecca and Tom among the baobabs at Lagoa Azul. Weckerphoto

GGIII.
There is already a book on the flora of the islands written by a man named A.W. Exell many years ago but there are still many groups that are poorly known on Sao Tome and Principe, including Tom’s and Rebecca’s acanths, and there is always the possibility of finding something new. Although these data are old, it is estimated that the flowering plants of Sao Tome and Principe are between 8 and 14% endemic, found nowhere else in the world. The numbers are a range because it depends upon which island and plant family you are talking about, but the endemicity is high.

Brillantasia, Sao Tome. Weckerphoto, GGIII
Tom and Rebecca have been working side by side with the cugumelo team but have been pressing and drying their plants at the small herbarium at Bom Sucesso, which is at about 1000 meters on the island of Sao Tome. The herbarium and delightful botanical gardens of Bom Sucesso were first built with support by ECOFAC, but now run by a local NGO called Monte Pico; their specialty is the endemic orchids, and there are guides for tours of the gardens, as well as guides available for hikes up into the “real” primary vegetation above. Our old friend, Bastien Loulomb, has been an advisor to Bom Sucesso and Monte Pico for a long time and has been of consistent help to me on the GG II and GG III expeditions.

GGIII team at Bom Successo, Sao Tome. Weckerphoto GGIII
I have always teased my botanical colleagues about the funny hats they wear in the field, and the fact that they never seem to get dirty like us herpetologists. Well, funny hats are a given (see the photo) but Tom and Rebecca get just as dirty as the rest of us. So far they seem to have collected whole samples, tissue for DNA and for karyotyping of all of the known endemics of their group, but have also collected great samples of a lot of other peculiar things, including the world’s largest Begonia, B. ebaccata, which grows to nearly 10 meters on Sao Tome. All duplicates collected by our botanists will reside at Bom Sucesso in the Herbarium.

Begonia baccata, largest in the world - Lagoa Amelia, Sao Tome

Weckerphoto, GGIII

Tom at Bom Successo. Weckerphoto GGIII
A high point was when Rebecca finally found an example of her “questing beast,” a tiny little acanth growing along the side of track up Pico Papagaio on Principe. She let out a loud shriek and dove to the ground. I wish I could remember the name of the thing, but Tom and Rebecca are on there way back the US as I write. Apparently, she needed sequence data from this little plant critter in order to “root the tree” of her current MSc thesis (the scientists among you will understand). Here’s a photo of her with her discovery.

Rebecca Wenk with her “questing beast.” Weckerphoto GGIII

Rebecca’s acanth crittter (Elytraria marginata).  Weckerphoto, GGIII

Finally, thanks to SCD a couple of weeks ago, we were offered a boat ride to the inaccessible southwest coast of Principe The southwest exposures of all of the islands in this chain, Bioko, Principe, Sao Tome and Annobon are inaccessible by land because they receive the brunt of the incoming weather, hence erosive force comes from the southwest. For the same reason the Portuguese were unable to cultivate these areas during their 500 years of colonization here and on each island these exposures are pretty much untouched by man. In one sense the trip was a near disaster; our small rubber dingy flipped and a lot of our equipment was compromised, most of it temporarily. But the mushroom guys were able to collect a bunch of stuff on a virtually untouched steep slope, and Tom and Rebecca were able to establish that the dominant plant group in the southwest of Principe is the Rubiaceae, members of the coffee family.

A melastome from Sao Tome.  Weckerphoto GGIII

We are posting a bunch of images, mostly by Wes Eckerman, that are unlabeled. The reason for this is that in many cases we do not know yet what the stuff is. Stay tuned.

Fisherman at Lagoa Azul. Weckerphoto GGIII
Next will be posting on my stuff, the creepy crawlies.

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Hello, folks. The blog is now up, thanks to the gang at WildlifeDirect. These postings will be somewhat retrospective as the first team has been on the islands for nearly three weeks already. Also, internet connections are very slow here (Principe, at the moment), but I will do my best. I notice we already have a response on the forum from a woman named Theresa, but I will have to learn how to respond later.

The GG III team: Perry, Wenk, Desjardin, Eckerman, Drewes, Daniel on Principe.

Macambrara, Sao Tome.  RCD photo GGIII
Six of us arrived about three weeks ago, we were joined last week by a 7th and here’s what some of us have been up to:

As leader of the GG expeditions I have been very excited to have our first botanists join an expedition: Dr. Tom Daniel, and his graduate student, Rebecca Wenck from CAS. Also particularly important to our goals has been the return to the islands of a mycologist (or in this case, two of them): Drs. Dennis Desjardin and post-doctoral fellow Brian Perry of San Francisco State University. I try to recruit scientists who study plant or animal groups that are poorly known in the Gulf of Guinea, and herein lies a story:

At the time of our second expedition (GG II) in 2006, there were only four species of mushrooms known from the Island of Sao Tome, and no one had ever explored the smaller, much older Principe for mushrooms (or cugumelos, as they are known here). Dennis Desjardin, a world mushroom authority was kind enough to join us for the first two weeks of GG II. At the end of his two weeks, Dennis had made 98 collections of at least 80 species of perhaps 40 genera of mushrooms, all from Sao Tome!

Needless to say, I was delighted to find this unanticipated level of diversity! Now, imagine how I felt two weeks later when, sitting in the steamy internet bar in Sao Tome, I read an email message from Dennis telling me that his luggage (and the mushrooms) had first been lost in Lisbon, and then later misdirected to the US through Newark, NJ instead of San Francisco where our institution is located. In Newark an agricultural/customs officer pulled the specimens out and promptly destroyed them (in spite of the permits, conspicuous labels, etc. on all of the packages). A devastating loss. I told this story in a public lecture a year ago, and thanks to the generosity of three private individuals in the audience, a grant from CAS and support from SCD we are back!

Part of our mission has been to recoup our mushroom losses from Sao Tome and to conduct the first survey of cugumelos on Principe. At time of writing, the whole team has walked up and down mountainous jungle trails from sea level to 1280 meters on Sao Tome, and with logistic support we did not have during GG I (2001) and GG II we have explored every accessible habitat type on Principe, once by boat. Turns out mushrooms grow in a lot of different habitats including not far from the high tide line on beaches.



Dennis and Brian tell me that the overall count of mushroom species so far, including both islands, is 220! We have 75 carefully dried and preserved specimens from Principe alone- this will be the first list ever. The number 220 includes some 30 species collected during GG II but not yet recollected during GG III. Every time I get really excited, Dennis and Brian are quick to say, “ Bob, this is only a snapshot in time! A couple of months from now, there may be a whole different group of cugumelos here.” It is way to early to tell what half of this stuff is, but Brain and Dennis were particularly excited about four mushrooms that were not expected in the Gulf of Guinea at all – these are ectomicorrhyzal (sp?); i. e. they form associations with living plants. Stay tuned.

Dr Dennis Desjardin on the hunt. Weckerphoto. GGIII

Dr. Brian Perry also hunting. Weckerphoto, GGIII
Our botanists (Tom and Rebecca), and herpetologists (me and Josef Uyeda, who joined us last week) have our own projects as well and Wes Eckerman has been photographing everything we do, every specimen we collect. More anon.

The Administration.  R. Wenk photo.  GGIII

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