Island Biodiversity Race

Category: Biodiversity, Gulf of Guinea, Island endemics, Sao Tome, barnacles, centipedes, coral, invertebrates, principe, snakes | Date: Nov 20 2009 | By: islandbiodiversityrace

It has been a busy couple of months, hence no posts on THE RACE.  In my last one, I hope I made it clear that scientists have senses of humor (my favorite ones do, anyway).  Here’s another fact you might not know; regardless of what he or she studies, there is probably not a single field biologist anywhere who does not have a secret dislike or even fear of one sort of critter or another.  With me, it has always been centipedes– even when I was a child.  I can’t bear the things!  And, naturally, there are some real monsters common on São Tomé.  The creatures in the shots below are about 10 inches long, sometimes they get larger!

Scolopendra subspinipes. D. Lin phot. GG II

S. subspinipes - Weckerphoto, GG III

These arthropods are more properly known as scolopendras, and they are voracious predators; the upper one is devouring a slug.  The two above are Scolopendra subspinipes, are native to Southeast Asia and thought to have been brought to the islands accidentally.  The Academy was just visited by Dr. Rowland Shelley, a specialist on millipedes from the North Carolina State Museum, who had a look at some of our critters.  He and his colleague, Dr. John Lewis of the UK identified these but, more exciting, the one pictured below.

Otostigmus productus DLin phot- GG II

This is a different species that was originally described from São Tomé over 120 years ago.  It is thought to also occur in West Africa; if this is the case, O. productus  is not an endemic species but it is probably naturally occurring.

Photo shoot on Sao Tome. Dong Lin, Fabio Penny and Ricka Stoelting -RCD GGI

Ricka Stoelting (above at right), my grad student and GG I participant, is putting the finishing touches on her manuscript on the fabulous São Tomé, “cobra bobo.” After submitting it for publication, she will pursue her PhD at the University of Wisconsin.

Schistometopum thomense - Weckerphoto, GG III

Ricka’s research has shown that this remarkable legless amphibian, Schistometopum thomense is indeed a true endemic species, having gotten to the island by natural means.  By studying the genetics of these bright yellow burrowers, she has learned that there are two different genetic groupings of the caecilian on the island and this is possibly related to volcanic activity within the last million years.

Principe Jita. Lamprophis sp. Weckerphoto GG III

Our snake project on “cobra jita” (Lamprophis - see earlier blogs) is ongoing; my intern, Lisette Arellano (above) has returned from the University of California, Santa Barbara and is working down in our molecular lab as I write.  Last summer we learned that although they are very similar in appearance, the snakes on São Tomé and Príncipe are genetically distinct from one another based on Lisette’s analysis of the cytochrome b gene.  We think that analysis of an additional nuclear gene will be useful.

Lisette Arellano at the Academy.  RCD

The big issue lies with the status of jita’s relatives on the mainland.  While we are now reasonably sure that the two island populations are separate species, we do not know what their relationships are to the at least 12 species of Lamprophis distributed widely in Africa; it is possible that either or both of our island snakes could belong to one these mainland species. Unfortunately  the relationships (systematics) of this whole group in Africa are poorly understood.  Dr. Chris Kelly of Rhodes University who is working on the entire complex has kindly sent us a number of tissue samples of Lamprophis from some West African localities, and these are what Lisette is analyzing now.  In June, Lisette is off to the University of Colorado to pursue her PhD.  Hopefully, we will have figured out our island snakes by then.

Dana Carrison off Principe.  Pola-Perez phot.  GG III B

Dana Carrison is an MSc candidate at San Francisco State University and was part of marine phase of GG III (see Send In the Marines).  She is the graduate student of Dr. Bob Van Syoc, a participant of both GG II and III marine expeditions.  Dana is nearing completion of her research on the barnacles she and Bob study and has this to say:

“So my latest findings are that we have not one, but two new species from the Gulf of Guinea. They are both found on Principe and Sao Tome. One only settles and lives on one species of gorgonian and the other is found on many different species of gorgonian. My DNA analyses are pretty much finished and they’re very agreeable.”

I should mention that the gorgonians to which Dana refers are studied by Dr. Gary Williams, also a Gulf of Guinea veteran of two expeditions.  Here are Dana’s new species:

Conopea new species #1   phot. D. Carrison

Conopea new species #2  D. Carrison phot

More anon and before our return to the islands.

Here’s the parting shot:

Chaplin, Executive Director, BomBom Island, Principe. Weckerphoto GG III

PARTNERS

We gratefully acknowledge the support of the G. Lindsay Field Research Fund, Hagey Research Venture Fund of the California Academy of Sciences, the Société de Conservation et Développement (SCD) for logistics, ground transportation and lodging, STePUP of Sao Tome http://www.stepup.st/, Arlindo de Ceita Carvalho, Director General, and Victor Bomfim, Salvador Sousa Pontes and Danilo Bardero of the Ministry of Environment, Republic of São Tomé and Príncipe for permission to export specimens for study, and the continued support of Bastien Loloumb of Monte Pico and Faustino Oliviera, Director of the botanical garden at Bom Sucesso. Special thanks for the generosity of private individuals, George G. Breed, Gerry F. Ohrstrom, Timothy M. Muller, Mrs. W. H. V. Brooke and Mr. and Mrs. Michael Murakami for helping make these expeditions possible.

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Category: Biodiversity, Sao Tome, biogeography, snakes | Date: May 05 2009 | By: islandbiodiversityrace

Snakes are not great over-ocean dispersers; they are certainly better than frogs or freshwater fish but not as successful as spiders, geckos and skinks. For instance there are no native snakes in the Hawaiian Islands although they do occur in the Galapagos, but these are much closer to a source continent. In spite of their small size and isolated nature, São Tomé and Príncipe have a rather surprising snake fauna; there are at least seven species, five of which we know to be endemic - they are found nowhere else. This group includes three species of “lower snakes” or scolecophidians; these are small, blind burrowing forms, two of which are endemic to São Tomé and one to Príncipe.

Rhinotyphlops newtonii, a burrowing scolecophidian from Sao Tome. (D. Lin phot. GG I)

The more advanced snakes (caenophidians) are represented by one endemic, diurnal (daytime) species on each island (belonging to two unrelated genera) and a nocturnal subspecies which is currently thought to be the same on both islands.

Hapsidophrys principis- (cobra sua sua:“snake fast”)- the endemic diurnal  species of Principe (D. Lin phot. GGI).

The nocturnal snakes are known as cobra jita (“snake slow”). I have mentioned these in earlier blogs, and my suspicions are that the two island populations are distinct endemics—we are beginning a molecular study this summer to test this hypothesis.

Cobra jita (”snake slow”), the nocturnal species from both islands?  (Weckerphoto. GG III)

But here I want to talk about the remaining snake found on São Tomé which the islanders call cobra preta (“snake black”); this is the only dangerous species on the islands, and it is a bit of a mystery to me.

The black and white, or Forest cobra - Naja melanoleuca. Ethnobiomed phot.

Widely distributed on the African mainland, this species is known as the forest cobra, or black and white cobra (Naja melanoleuca), and it is quite a venomous and formidable animal. In some parts of its range it can exceed 3 meters in length (10’).

Forest cobra distribution.  map by Nils Boyson

Head of Forest or Black and White cobra, Naja melanoleuca.

This snake, like most true cobras, displays a hood as part of its defense system, essentially making itself look larger in order to warn of its presence. Like all members of family Elapidae, cobra preta has erect front fangs that are hollow and syringe-like, and it injects prey animals with venom that attacks the nervous system (neurotoxin).

[l.]  C. melanoleuca fang showing aperture (Bruce Young) [r.] direction of venom injection (E. Jose)

All of the São Toméans know of cobra preta and fear it, although I have no idea how frequently citizens are bitten. Based  on a dead-on the-road specimen at nearly sea level in the south of the island, we know it occurs in lowlands, but I suspect it is more common in the mid-level forests; during GG I, we purchased a number of skins from farmers at Bombaim, which is at middle elevation.

Dead on the road, south Sao Tome. (RCD phot. GG recon 2000)

Joel Ledford with Bom Sucesso specimen. (J. Ledford phot. GG I)

The 2- meter specimen above was killed by locals near the Botanic Gardens and Herbarium of Bom Sucesso at about 1000 m, and we were able collect it during the GG I expedition.

During GG II in 2006, we encountered a very large specimen while collecting along an aquaduct in the Contador Valley on the west side of the island at 700 m; in fact, several of us nearly stepped on it before we were aware of its presence.

On our most recent foray, GG III A, we were again on the Contador Aquaduct when a middle-sized snake was killed by locals around a bend in the road, less than 100 m from where we were working.

Contador Valley specimen (Weckerphoto GG III)

Regrettably, they had beheaded the specimen, and so it was of no value as a voucher specimen; however, we were able to photo-document the animal and I removed some liver tissue for future analysis.

Liver tissue removal. (Weckerphoto. GG III)

The presence of the cobra on São Tomé Island is widely considered to be the result of human introduction, most likely accidental (it is hard to imagine an individual bringing a deadly snake on purpose!). Physically it appears to be identical to the widespread Naja melanoleuca of the mainland. Accidental introduction makes ecological sense to me as well because the species does not really fit into this old ecosystem as we are beginning to understand it. We know that the other higher snakes feed on endemic prey species such as frogs and lizards. But aside from some birds, there do not seem to be endemic prey species that are of sufficient size to sustain a large, heavy-bodied snake like cobra preta; on the other hand, plenty of rats, chickens, etc. have been brought over by humans since the 15^th Century.

Two of the top African cobra experts are Drs Wolfang Wuster of the University of Wales and Donald Broadley of Zimbabwe. They are currently working on this species, and we have been sending them our tissue samples for DNA analysis. Soon, we should know whether or not this large cobra drifted out to the islands on its own and has since been genetically diverging, or whether it was brought to the island through human agency. Wuster and Broadley are currently describing a new species from Ghana that was long thought to be the species Naja melanoleuca.

Our parting shot:

Roadside enterprise on Principe(Weckerphoto GGIII)

PARTNERS

We gratefully acknowledge the support of the G. Lindsay Field Research Fund, Hagey Research Venture Fund of the California Academy of Sciences, the Société de Conservation et Développement (SCD) for logistics, ground transportation and lodging, STePUP of Sao Tome http://www.stepup.st/, Arlindo de Ceita Carvalho, Director General, and Victor Bomfim, Salvador Sousa Pontes and Danilo Bardero of the Ministry of Environment, Republic of São Tomé and Príncipe for permission to export specimens for study, and the continued support of Bastien Loloumb of Monte Pico and Faustino Oliviera, Director of the botanical garden at Bom Sucesso. Special thanks for the generosity of private individuals, George F. Breed, Gerry F. Ohrstrom, Timothy M. Muller, Mrs. W. H. V. Brooke and Mr. and Mrs. Michael Murakami for helping make these expeditions possible.

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Category: Biodiversity, Gulf of Guinea, Island endemics, Sao Tome, frogs, gigantism, principe, snakes | Date: May 27 2008 | By: islandbiodiversityrace

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!

PARTNERS We gratefully acknowledge the support of the Research Investment Fund of the California Academy of Sciences, the Société de Conservation et Développement  (SCD) for logistics, ground transportation and lodging, STePUP of Sao Tome http://www.stepup.st/ and especially the generosity of three private individuals, George F. Breed, Gerry F. Ohrstrom and Timothy M. Muller, for making GG III possible.

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Category: Biodiversity, Gulf of Guinea, Sao Tome, biogeography, frogs, principe, snakes | Date: May 03 2008 | By: islandbiodiversityrace

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

PARTNERS We gratefully acknowledge the support of the Research Investment Fund of the California Academy of Sciences, the Société de Conservation et Développement  (SCD) for logistics, ground transportation and lodging, STePUP of Sao Tome http://www.stepup.st/ and especially the generosity of three private individuals, George F. Breed, Gerry F. Ohrstrom and Timothy M. Muller, for making GG III possible. More anon.

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