Sorry, I love titles like this… and I have more! Actually, there are no toads (Bufonidae) on São Tomé and Príncipe; interesting in itself because seven other amphibian species of five different families have survived the ocean crossing during the many millions of years since the islands first emerged. Moreover, toads are common in almost every conceivable terrestrial mainland habitat.

My last two blogs have been a bit academic. Having laid the biogeographical ground work, it is probably time to get back to the unique, endemic island critters. The tiny, 31-million year old island of Príncipe is the only home of Africa’s largest treefrog, Leptopelis palmatus – the Príncipe Giant Treefrog. It is one of the world’s rarest frogs, as well.

L. palmatus – D. Lin phot. GG I

Let me be quick to point out that the Príncipe critter is not Africa’s largest frog; that title belongs to Conraua goliath (below), which is found on the mainland in southern Cameroon and Gabon. In fact, the goliath frog is the largest in the world but it is not related to any on São Tomé and Príncipe– no members of its family have made it across the saltwater gap to the islands, or if they ever did, they have not survived.

Conraua goliath—J.-L. Perret phot.

Leptopelis palmatus is the largest African treefrog (emphasis on “tree”) — frogs that are adapted for climbing with, among other features, enlarged finger and toepads. As I have pointed out in earlier blogs, gigantism is a relative thing; the giant endemic plants, frogs, birds and lizards of São Tomé and Príncipe are bigger than all of their relatives but they are not necessarily so large you trip over them (like Galapagos or Aldabra tortoises); they are simply larger than all of their relatives. The two images below put this frog in some perspective, and I think you will agree that this is one BIG treefrog.

Me, with the first female. R. Stoelting phot. GG I

The frog on Dong Lin, our photographer. R. Stoelting phot GG I

This species was first described in 1868 on the basis of a single female specimen, housed in the Berlin Museum. At the time of GG I in 2001, the Príncipe giant treefrog was known only from this single type specimen and seven additional specimens, all females, collected by local Príncipeans for a Swiss colleague named Catherine Loumont. The largest of Loumont’s specimens is 110 mm from snout to vent (we do not include legs when we measure frog sizes), and even after our years of work, this specimen remains the largest ever found – it is nearly 30 mm longer than its nearest mainland relative, Leptopelis macrotis, distributed from central Sierra Leone to Ghana. One of several differences between the two species is the striking deep-red eyes of our island endemic.

The eye of the Príncipe giant treefrog. D. Lin phot. GG II

This first specimen we found during GG I (first three treefrog images, above) was yet another female, 108 mm in length. Our mammalogist, Doug Long, was led to the critter by some kids from the now-defunct plantation of Sundi in northwest Príncipe. Sundi may no longer function as a plantation but it is still inhabited by the descendents of former workers—lots of them, there is even a mayor.

Doug Long and the Sundi kids. RCD phot. GG I

The arrival of this frog was greeted with great enthusiasm by yours truly; here in my hands one of the rarest frogs in the world! And it was huge! I was not surprised to learn that it had been found on the ground, as it is hard to imagine something so bulky climbing around in bushes and trees. The male of this species was completely unknown, so far as we knew at the time,. None had ever been collected, photographed nor described in the scientific literature. So we also knew nothing about the species’ breeding biology, male advertisement call or tadpole. At the time, we were unaware of a blog posted two years before our visit by Jonathan Bailey on the Gulf of Guinea Conservation Group website, entitled “One month in the Forest of Príncipe.” Jonathan (now Dr.) Baillie described hearing the calls of male L. palmatus as “like a pop bottle being continuously opened.” He heard them high up on Pico do Príncipe near a small stream at about 700 m and actually collected two of them which had been deposited in the Natural History Museum in London. But during GG I, the male giant treefrog was terra incognita, so far as we were concerned.

Second female from Rio Papagaio. J. Ledford phot.. GG I

During a second GG I visit to Príncipe a few weeks later, my then-graduate student, Ricka Stoelting, collected another female along the Rio Papagaio, a large-ish river that flows through Príncipe’s only town, Santo Antonio. It was also of a rather dull in color but with white spots. We have since learned that this is about as brightly colored as females get.

Rio Papagaio in town, downstream. RCD phot. GG III

Ricka Stoelting, my graduate student on Sao Tome. RCD phot. GG I.

During this second visit, Ricka and Dr. Sarah Spaulding ascended Pico do Príncipe to the top and camped at nearly the same spot where Jonathan Baillie had been two years before. There she found the males, lots of them, calling from bushes and branches at night near a very small creek.

Tiny creek on the Pico. J. Uyeda phot. GG II

Ricka brought the series of males back down the mountain, and they were astounding. Unlike the females they were very brightly colored and highly variable, in pattern, as well; this variability is rather unusual in frogs, although there are some species that are sexually dimorphic for color. And they were much, much smaller than the females, though we knew they were full-sized breeding adults. During later analysis we learned that the largest breeding males are only about 41% of the size of the largest females, a size disparity that is striking.

First series of live males (far right is a juvenile). J. Ledford phot. GG I

Ricka never heard them calling and anyway she had no way of recording them if they had. One of the parameters we use in establishing relationships among frog species is analysis of the voice (or advertisement call.). Males call to attract females, and at the same time to advertise their presence and territory to other males. The advertisement call is species- specific and obviously adaptive when there are other species utilizing the same water for breeding. To really define Leptopelis palmatus, I needed a recording of the voice, and this was to become a priority in the future. Below is a preliminary analysis of the call of another Gulf of Guinea frog species which we think is present on both islands. Here, we are comparing the advertisement calls of males from two different localities on both islands, and we can see that they are basically the same.

Preliminary sonograms of Oceanic treefrog. Marshall/Drewes construct.

Back at the Academy, Ricka and I prepared the first formal description of male Príncipe giant treefrogs. Now aware of Baillie’s blog, we read his word description of the advertisement call. Although the Principeans insisted the frogs did call, it remained an open question, especially when I learned from anatomical study that the male frogs lack vocal sacs and vocal sac openings, features that most calling frogs possess (including other members of the genus Leptopelis). GG II in 2006 included Josef Uyeda as my student (now a PhD candidate at Oregon State University). Josef was working on a different group of island endemics called puddlefrogs (see earlier blog: “We Find Jita”) but when we were on Príncipe, I sent him up the Pico with his friend Mac and the same guide, Manona, who had led Jonathan Baillie and Ricka years before. They were armed with my old Sony cassette recorder (my iPod had failed). Bear in mind that the only known localities for males were at nearly 700 m, high on the Pico and while this made no biological sense, that’s where my stalwarts had to go. This is no small matter given the topography of the island, but graduate students are good at this sort of thing and anyway, they tend to be younger and more vigorous than their advisors!

Principe terrain. Pico do Príncipe is in the clouds to the left of the large Pico Papagaio. R. Wenk phot. GG III

Josef Uyeda hunting for caecilians on São Tomé. D. Lin phot. GG II

While in the same general area as earlier workers at about 700 m, Josef got a lot done but the party was caught in heavy rains. He heard males and saw them calling but only managed some rather distant, poor-quality recordings (the conditions were miserable), but now at least we knew that the frogs did, indeed, call. GG III, last spring, provided some answers, thanks in part to our friend Ramos of Bom Bom Island. Ramos is assistant manager of the resort, a native Principean and a keen, observant naturalist. See the photo of Ramos in the “We Find Jita” blog. I described our past difficulties in trying to record the voice of the Príncipe giant treefrog to him, and he grinned and said, We will go to my roça (farm) on Pico Papagaio and at 5:30, we will get them! I was highly skeptical…

Roça Papagaio, Ramos’s farm at 250 m. R. Wenk phot. GG III

Ramos’s farm is in the forested area on the northern flanks of Pico Papagaio at about 250 m. Just before you reach it on a dirt steep uphill road, you cross a tiny creek; this is where Ramos took us – about 30 m up that small creek, thick with dense undergrowth, and there we sat, waiting for the forest cacophony of grey parrots, mona monkeys to subside. Nothing much happened. I had my iPod with recording head at the ready. We waited in the gathering gloom for about 20, maybe 30 minutes, Ramos grinning throughout and occasionally exclaiming, Just wait. We will get them!

Me waiting, iPod in hand, for the giants to call. T. Daniel phot GG III

And sure enough, we began to hear frogs calling. I looked at my watch. It was 5:30.The call is certainly a strange one; it lacks resonance (remember males don’t have a vocal sac) and thus it is rather flat and unmelodius. Rather than my trying to describe it or arguing with earliler descriptions, you can listen to it yourself:

 

 Frog Calls [0:05m]: Play Now | Play in Popup | Download

And here are a couple of photos of the male that was calling, taken by Wes. These are un-posed and before we collected it as a voucher specimen for the voice:

Weckerphoto GG III

Weckerphoto - GG III

There are still great gaps in our knowledge of this most unique frog. Obviously, the males are well-distributed in the lower elevations; we just have not been in right place at the right time. We still cannot explain why females are dull and rather cryptic in coloration and usually found on the ground, while there appears to be no selection for color in males. The dull color of females seems consistent, as a couple of months ago I found six additional females (no males) collected in 1988 at the Doñana Institute in Seville and they were clearly drab in life; my colleagues at Donana tell me they were collected on the ground in lowland localities at Rio Papagaio and Bela Vista.

Six female Seville specimens at Donana Institute. RCD phot.

We still have not observed breeding, nor have we ever seen tadpoles. In this genus, Leptopelis, they are very distinctive, and I would predict the tadpole will look like this:

A Leptopelis tadpole. Image courtesy of Dr. R. Altig

Here’s the parting shot:

Nezo, of Angolares, Sao Tome: artist, musician, restaurateur and worthy man - Weckerphoto GG III

PARTNERS We gratefully acknowledge the support of the G. Lindsay Field Research Fund, Academy 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 Sao Tome and Principe 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 four private individuals, George F. Breed, Gerry F. Ohrstrom, Timothy M. Muller and Mrs. W. H. V. Brooke for making these expeditions possible.

First, I thought it would be useful to illustrate, in one place, how many scientists have been involved in the Gulf of Guinea expeditions since 2001 including the folks going in January 2009 (Gulf of Guinea III B). 

In Part I of this blog, I suggested that it is not just the high numbers of plants and animals that are endemic to these islands that is striking; it is also the fact that many of them are particularly poor dispersers over salt water and, according to dogma, they just shouldn’t be there! A scientist would never predict the presence critters like amphibians on oceanic islands. Don’t believe me? Even Darwin himself made the observation:

 Courtesy Dr. M. Vences, University of Braunschweig.

Amphibians and burrowing reptiles are among the most obvious of the unlikely inhabitants on the two islands but there are more subtle oddities as well.  The plant group Acanthaceae (shrimp plants), which are the specialty of Dr. Tom Daniel (GG III – see May 2, “News From the Flower People”) is another group whose presence is surprising.  

Dr. Tom Daniel. Lagoa Amelia, Sao Tome (RCD phot. GGIII) 

Heteradelphia  paulowilhelmina– an endemic genus? Weckerphoto GGIII  

The seeds of this group have no “wings” or other morphological adaptations allowing them to be blown by winds (wind dispersal is very common among plants – think of dandelions).  They do not float, they are too heavy, and anyway they are not salt-tolerant. If that were not enough, shrimp plant seeds do not have endosperm; i.e. they are not nutritious and thus are very unlikely to be routinely eaten by birds or mammals, then transported as stomach contents.  In fact, seed dispersal in this group is accomplished by the capsule that bears the seeds “exploding” and casting the seeds a matter of a few meters away from the parent plant.  Yet, there are 15 species native to the islands (non-introduced), two of which are endemic.  How did they get there across the water? 

I think the most likely answer to this question is that in the distant past these species crossed the marine barrier between Africa (the source) and the islands by floating on rafts.  My colleagues and I published this “rafting hypothesis” about a year and a half ago, largely based on the study of one group of frogs; however, the more I learn about the island endemic fauna, the more I am convinced that this is the most likely scenario.  

The first thing to remember is that two of the mightiest rivers on earth feed directly into the Gulf of Guinea - the Congo and the Niger. The Congo especially has an enormous drainage from deep within the African interior, and we know that the Niger flowed from current Lake Chad not so long ago; these might be considered amphibian freshwater highways from the interior to the coast.  It is not difficult to envision rafts of matted vegetation, tree trunks etc., floating downstream on one of these great rivers and being discharged into the Gulf of Guinea.  But we propose rafts composed of huge chunks of riverbank, chunks large and diverse enough to harbor burrowing forms and amphibians. 

Illustration by Richard E. Cook, San Francisco.

Such rafts might be many acres (hectares) in size such as in this painting by my artist friend, Richard E. Cook. Rafts of this size might be expected to have rotten logs, trees, bushes rocks etc.  Does this actually happen? Yes, such huge rafts containing all manner of wildlife are fairly common breaking off and floating down the Amazon and the La Plata (they are called Camalotes); however, in the case of the Amazon, they are not often discharged into the Atlantic. Rather, they tend to accrete together at the delta, forming large masses. 

Satellite image, from World Wide Web.  

In the satellite image above, the red star indicates a large accretion island in the Amazon Delta called Marajó – it is about the size of Belgium! I can think of two possible explanations for why islands formed in the Amazon accumulate at the delta rather than float out to sea. 

RCD phot. 

First, notice above that the water remains relatively shallow for a great distance seaward from the Amazon Delta; this is because the continental shelf is about 200 miles wide before dropping off into great depths.  By contrast, the continental shelf off the Niger and Congo Rivers is much narrower (arrows on the right); moreover, just offshore from the Congo Delta is a deep abyss called the Congo Canyon.   Second, I think the water velocity in the Amazon is significantly lower in the Amazon than it is in the Congo, at least.  In fact the Congo is only navigable for about 80 miles inland.  The yellow star in the image below is the town of Matadi, which is far inland as one can get by boat.

 Matadi, D.R.C., as far as you can go.  (RCD phot. 1984 

Upstream from Matadi are a series of rapids or cataracts formed as the river cuts though the African coastal uplift. 

Congo cataract. Google Earth image.

Rapids below Stanley Pool, D.R.C. -  Souljah phot.  WWW.

 These rapids increase the water velocity so that I suspect the river is much swifter overall than the Amazon, and it is far more likely that floating objects would be ejected out over deep water from the mouth.  How such floating objects would survive the cataracts themselves is an open question.  Given a large chunk of riverbank being ejected out into the Atlantic Ocean from the mouth of the Congo, what happens next?

Google Earth, RCD composite.

 The image above shows the mouths of the Congo and Niger (yellow stars) and the directions of the dominant ocean currents in the region.  Note that any floating object ejected from the Congo River will immediately encounter the Benquela Current and be carried north; such an object from the mouth of the Niger will be carried East by the Guinea Current.  It so happens that these two major currents converge to form the South Equatorial Current which flows due west, right through the central Gulf of Guinea Islands!  Conditions being perfect, we estimate that a floating object would take less than two weeks to reach São Tomé or Príncipe from the mouth of the Congo.     But, given our knowledge of the physiology of amphibians, what about the effects of the saltwater during the voyage.  Well, it seems that at predictable times of the year, the surface water of the Gulf of Guinea is not all that salty. 

From Measey, et. al. (2007). Journal of Biogeography

Notice that during the rainy season (around February) the surface salinity around the islands drops to around 31 parts per thousand of salt (technically it is brackish). Recall that because of differences in density, freshwater floats upon salt water. This sharp decrease in surface salinity is due to massive freshwater discharges of both the Congo and the Niger into the Gulf, plus the extremely high precipitation in the area as a whole.  And of course, with high flow rates and the two mighty rivers in spate, this would be the time of year when pieces of riverbank would be most likely to break off and flow downstream.  So a combination of factors, the locations of the rivers, the directions of the dominant ocean currents and periodic surface salinity changes, all point to rafting as the most likely way the amphibian ancestors of the current endemics actually arrived on the islands. We cannot prove this happened; we simply claim it is possible and likely.  Moreover, , one must bear in mind  that there has been a 13 million year period during which it might have in the case of São Tomé; as for Principe, it has been sitting out there “available for colonization for over 30 million years! 

Here is the parting shot: 

Angle of Repose on Principe. Weckerphoto, GG III.

PARTNERS We gratefully acknowledge the support of the G. Lindsay Field Research Fund,  Academy 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 Sao Tome and Principe 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 four private individuals, George F. Breed, Gerry F. Ohrstrom, Timothy M. Muller and Mrs. W. H. V. Brooke for making these expeditions possible.             

Our research on the unique flora and fauna of São Tomé and Príncipe Islands is allowing us to document the different kinds of critters that are endemic; i.e., found there and only there. And there are many of all kinds. It is important for us to do this so that the citizens of the islands are aware of how different these islands are from the rest of the world so they can make informed decisions in the future.  I have already stressed how poorly known the biota of these islands is, and a good example lies in our mushroom work which you can read about in “May Day Mushroom Madness“, below.  Prior to our work, only four species had been listed from São Tomé and no one had ever looked at Príncipe. Now, as a result of our most recent expedition (GG III (A), we have 225 species, 75 of which are listed for the first time from Príncipe—and our mycologists Dennis Desjardin and Brian Perry tell me many of these are new to science. 

Cross-section of G of G Islands and mainland highlands (RCD compiled image)

As I established in the first blog below, “Islands at the Center of the World,” São Tomé and Príncipe, and also tiny Annobón are classic oceanic islands; they have never been attached to mainland Africa.  This is obvious from the island cross-section above – you can see that the first island, Bioko, is separated from the mainland by very shallow water (arrow), and it was clearly connected to the mainland perhaps numerous times during the Holocene as sea levels rose and fell.  However our oceanic islands are surrounded by water depths of up to 4,000 meters and could never have been connected to the mainland.  This means that everything living on the islands had to get there from the mainland (or somewhere else?) across several hundred kilometers of deep salt water.  As described in the first blog, this happens by random chance and  we call it dispersal. In the case of the Gulf of Guinea, there has been a lot of time for this to happen: São Tomé and Príncipe are very old as islands go (the Seychelles are a special case).

Island ages. (RCD  combined image)

Once established, colonist species begin to accumulate genetic changes and ultimately become endemic, that is physically and genetically isolated from their ancestors on the distant source continent.  We are able to predict the sorts of plants and animals we are most likely to find present and established on oceanic islands.  Distance from the source is a limiting factor and, of course, so is island area— the larger and more diverse the island the greater the array of suitable niches for colonizers.  But for an individual species the most important parameter has to do with behavior, morphology and physiology in determining “who gets there successfully.”  It is a fact that some species are better able survive crossing broad saltwater barriers than others; these, we call good dispersers.  Good dispersers include many plant species with either resistant seeds (e.g. palms) or seeds that are wind-dispersed. Spiders, notably species that disperse by “ballooning,” are also good dispersers; as tiny juveniles, they spin a single long strand of silk that is caught by air currents, enabling them to be carried great distances. Some lizards such as geckos and skinks commonly make good dispersers and successful colonizers of oceanic islands. 

A salticid spider of the genus Eris. (B. Marlin phot. on www)

Plants like dandelions have wind-dispersed seeds and are good colonizers. (C. Higgins phot. www) 

Hemidactylus greefi, a gecko endemic to both islands (D. Lin phot. GG II)

Conversely, there are poor dispersers, species we would never expect to cross expanses of salt water; a classic example is primary freshwater fish (species that evolved in freshwater, as opposed to some groups that are anadromous, spending part of their life cycle in both) There are groups that evolved in saltwater but have members that readily adapt to freshwater; these are called secondary freshwater fish. All of the fish we have found in the many streams of Sao Tome and Principe are secondary freshwater fish, mostly gobis.

 Sicydium bustamanei, a secondary freshwater fish from Rio Micondo, Sao Tome. (RCD phot. GG I)

São Tomé and Príncipe are remarkable for the large number of endemic species that live there, but it is the nature of some of these species that is even more fascinating to me.  Some of these endemics fall into the category of “poor dispersers”; I mean really lousy dispersers.  Amphibians, because of the structure of their skin, freshwater aquatic larvae and unshelled eggs, are second only to primary freshwater fish in their lack of tolerance to saltwater. They are never predicted as successful colonizers of oceanic islands.  Think of it: there are no native amphibians whatsoever on either the Hawaiian or the Galapagos Islands.  Prior to our work in the Gulf of Guinea, the only other frog group shown to have crossed saltwater barriers are populations of rocket frogs (Ptychadena) on Madagascar; this was not dicovered until genetic work was completed in 2004.  But São Tomé and Príncipe are not limited to just one amphibian endemic colonizer; there are fully seven species there belonging to five families, each of which must have somehow crossed the broad expanse of saltwater separating these islands from Africa.

The Amphibians of Sao Tome and Principe. (RCD compliled photos of D. Lin (GG I, II, Weckerphoto, GG III; light green=Sao Tome only; light blue=Principe only; white=both islands)

The fact that there are any amphibians at all on these islands is surprising enough, but that such a diverse fauna exists there which also includes a legless burrowing caecilian, the cobra bobo (found only on São Tomé), is truly mind-boggling.  How does such a creature get across the ocean?  

“Cobra bobo,” Schistometopum thomense. Sao Tome. (Weckerphoto - GG III). 

Before we try to answer this question, there are some other endemic species on the islands whose presence we would not  predict.  Except for bats (especially of the Family Vespertilionidae), mammals are considered very poor dispersers, largely for physiological reasons.  We mammals have to continually eat (stoke the fire, so to speak) in order to maintain our constant body temperatures; for this reason, mammals cannot tolerate long periods of exposure and are unlikely to survive long ocean passages before succumbing to hypothermia (unless, of course, there is food available).   And among mammals, the critters that have the largest heat loss problems are the shrews; these tiny creatures have such a large surface area relative to their mass that they lose heat constantly and rapidly, to the point that an individual shrew has to eat continuously just to avoid dying by hypothermia.  These would be the very last sorts of mammals we would predict to successfully colonize an oceanic island; yet there is an endemic shrew on São Tomé, Crocidura thomensis (we have not yet seen it, although I am informed there are scientists currently looking for it), and an species assumed to be from the mainland, the White-toothed shrew (C. poensis) inhabits Príncipe.  We have to consider the possibility that this latter species was brought in by man, but if not and if C. thomensis is a naturally occurring endemic, how on earth do such fragile creatures survive an ocean crossing?

Crocidura suaveolens, an Old World Shrew.

Crocidura poensis (?). A dead-on the road shrew on Principe Id. (J. Uyeda phot. GG III)

Newborns found on Principe, near Santo Antonio. (D. Lin phot. GG II) 

There are a number of ways species can be naturally dispersed across saltwater barriers: some can fly (bats, birds, many insects), they can be carried by winds and storms (seeds, insects, birds); some salt-tolerant species can float or swim (palm seeds, tortoises to Galapagos and Aldabra, the ancestors of the marine and land iguanas of the Galapagos).  Darwin postulated that amphibian eggs might be dispersed on the feet of wading birds, but to my knowledge this has never been demonstrated.   A mechanism of dispersal that is frequently invoked by biogeographers is rafting.  I remember as a student that it was not difficult to imagine a gecko or its eggs, being carried out to sea on a floating palm tree or chunk of riverbank and then ultimately washing up on an island shore.  This no doubt has occurred many times throughout history, but it of course requires that the hitchhiker have certain tolerances to exposure, potential starvation, etc.  My colleagues and I suggest that rafting is the most likely scenario for the colonization of the Gulf of Guinea Islands by the amphibians and reptiles, but on a much grander scale than a few pieces of floating matter over time.  I say “much grander” because along with the caecilian, Schistometopum thomense, nearly half of the endemic reptiles on the islands are also fossorial, legless, burrowing species.  Their continental relatives are all fossorial as well, so we know that loss of limbs has not occurred since these species arrived.  It is extremely difficult to imagine a mechanism by which burrowing species can cross a saltwater barrier unless they are floating on and carried by really large rafts.  

Legless endemic Reptiles of Sao Tome and Principe. (D. Lin phots. GG I, II)

The celebrated endemic “Cobra bobo”, a legless burrowing amphibian found only on Sao Tome Island (Weckerphoto - GG III)

I will explain our hypothesis in more detail in Strange Bedfellows, Part II. 

Here’s the parting shot: 

Willing helpers at Sao Nicolau, Sao Tome Id.  (Weckerphoto - GG III)

 PARTNERS 

We gratefully acknowledge the support of the G. Lindsay Field Research Fund,  Academy 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/ the staff of the Ministry of Environment, Republic os Sao Tome and Principe and especially the generosity of three private individuals, George F. Breed, Gerry F. Ohrstrom and Timothy M. Muller, for making these expeditions possible.   

Having read my previous blogs, you might have the impression that all of our efforts of discovery on these unique islands are limited to the high forests and other habitats of the terrestrial environment, and that most of the neat unknown and undescribed stuff is to be found on land.  Such is definitely not the case.  The marine and freshwater realms have not escaped our attention, and they probably contain as many biological mysteries as the land does, maybe more.  Let’s not forget that the inshore marine communities, just like the aerial parts of the islands, have been isolated for millions of years. 

 M. Campbell (Willamette Univ.) and Dr. Iwamoto on Sao Tome GG II (Photo. RCD)

The offshore fisheries of São Tomé and Príncipe are very rich but poorly protected; I have been told that the government cannot afford to monitor the trawling of other countries within their exclusive economic zone, and this is a tragedy not only for economic reasons. The fact is that we still do not fully understand the inshore marine fauna of this unique archipelago.

Tomio off  the Jockey’s Bonnet, Principe. GGII (Photo RCD) 

Dr. Tomio Iwamoto, chair of the CAS Ichthyology Department was a member of both GG I and GG II.  Much of his work in 2001 and 2006 involved sampling the many freshwater rivers of both islands (which I will describe later); but he made some of his most interesting discoveries simply by interacting with the local fishermen.  

Fisherman way offshore, Principe. GG I (RCD Photo).

Fishermen off Ilhéu das Cabras, Sao Tome.  GGII (photo: R. Van Syoc)

For instance one day during GG I , Tomio and I watched a group of fishermen seining from Praia Lagarto on the northwest cove of São Tomé island.  Tomio asked them if he could examine their catch and discovered several species of fish not known to occur in São Tomé and Príncipe. He bought them from the fishermen on the spot and preserved them as specimens.

 [Beach seining, Sao Tome.   GGI (RCD photo)

 Each day in the afternoon , the fishing boats arrive on the beach of Baia de Ana Chavez, directly adjacent to the central market of São Tomé city. Many of the city’s citizens flock to the beach to buy directly from the fishermen.  

Arrival of the fishing fleet.  GG I (J. Ledford phot) 

  Buying directly off the boats. GG I (J. Ledford phot.)

 We discovered that the fishermen would allow us to examine the contents of their nets while they were sorting through their catch for sale and would sell us whatever we wanted.  Tomio employed the same “field technique” on Príncipe during in 2006 and as a result, he was able to add more than sixteen species of marine fishes to the current list of species known from the islands! 

 Tomio heads for the beach and the boats.  GG I (J. Ledford phot.)

 In 2006 (GG II), the team was joined by Drs. Gary Williams and Robert Van Syoc, both of the Academy’s  Department of Invertebrate Zoology and Geology.  Bob is a specialist on the world’s barnacles and Gary is one of the foremost authorities on various groups of corals. Together the two surveyed the waters of São Tomé with the expert help of Jean-Luis Testori, owner, divemaster and skipper of Club Maxel on the big island.  

Dr. Gary Williams. GG II B Van Syoc photo) 

[Gary (left) and Jean-Luis collecting, Sao Tome.  GGII (B.Van Syoc phot.)

Eunicella, a sea fan of Sao Tome.  GG II (B. Van Syoc phot.)

Gary collected twelve species of octocorals including eleven sea fans, also known as gorgonians; all of these species are endemic to the eastern tropical Atlantic.  At the same time, Bob Van Syoc made a synoptic survey of the São Tomé barnacles.  All of the barnacle species so far identified are known from oceanic islands (see the first blog on oceanic vs continental islands), none of the intertidal genera or species commonly associated with continental shores have been found on Sao Tome.  Bob and Gary will return to São Tomé and Príncipe on GG III(B) in January, 2009 and both are eager to sample and compare the same kinds of organisms inhabiting the much older inshore marine communities of Príncipe. 

Dr. Bob Van Syoc, barnacle specialist (R. Van Syoc phot!)

Stony coral with barnacle (arrow) Sao Tome.  GG II (B. Van Syoc phot)

One of the most exciting events during GG II was the discovery by Bob of what appears to be an undescribed species of barnacle of the genus Conopea, which may be symbiotic with one or more of Gary’s sea fans.  Dana Carrison, Dr. Van Syoc’s graduate student at San Francisco State University, is in the process of describing this new species for her MSc. degree and will join GG III(B) on the expedition to Príncipe to search for similar species and relationships. 

Gorgonian (sea fan) with Conopea (arrow).  GG II B. Van Syoc phot) 

Dana Carrison, Bob’s graduate student from San Francisco State U. (NOAA phot)

Dr. Marta Pola-Perez is an authority on nudibranchs, or sea slugs, and will be along on GG III (B) as well. Marta is a post-doctoral fellow of the Department of Invertebrate Zoology and Geology and will be making the Academy’s first survey of these spectacular creatures in the Gulf of Guinea. 

Dr. Marta Pola Perez in Cuba 

Tambja tentaculata, a nudibranch from Guam (M. Pola-Perez phot) 

Finally, the Gulf of Guinea III marine expedition of early 2009 will include two additional new scientists:   Dr. John McCosker, Chair of Aquatic Biology at the Academy, is perhaps most famous as an authority on great white sharks; in reality he is one the world’s leading experts on eels, his real love. After the group finishes work on Príncipe, John will probably return to São Tomé to look for eels.

  Dr. John McCosker, eel specialist (P. McCosker phot)

 Brachisomophis, a snake eel described from Principe. (P. Wirth phot)

Dr. McCosker will be joined and assisted by David Catania, Collections Manager of our Ichthyology Department.  David has collected fish all over the world, and while accompanying Dr. McCosker during SCUBA operations, he also plans to continue combing the São Tomé fish market and meeting the fishing boats as did Dr. Iwamoto during GG I and GG II. 

 Catania electroshock fishing  in Yunnan (D. Lin phot)

Who knows how many undescribed species are caught each day by the hard-working fishermen of the Republic of São Tomé and Príncipe?  The islands continue to amaze and enchant– There is much more coming.

 The parting shot: 

 Nova Cuba, Principe.  GG III (Weckerphoto)

PARTNERS 

We gratefully acknowledge the support of the G. Lindsay Field Research Fund and 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 these expeditions possible.

A recurrent theme in our work in the Republic of São Tomé and Príncipe is the continuous reminder of how little we and the 160,000 citizens of these fragile little islands know about the unique biology found here.  I have already told you that when we first arrived, there were but four species of mushrooms listed from São Tomé and none from Príncipe; we now have at least 180, and the first ever recorded from Príncipe (75), the older of the two islands. Many of these are species new to science and are being described for the first time; this is a huge jump in the island biodiversity list and there is much more to come. 

During our first expedition in 2001 (GG I), we were interviewed twice by the local television station in São Tomé.  In the second interview two weeks after our arrival, I had the whole gang prepared to show some of the specimens we had collected.  When we showed him the scorpions, the reporter, Gui Gui, went nuts!  Neither he nor any other citizen we have spoken to since, has ever seen nor heard of a scorpion.  And yet they are quite common at night (along with numerous geckos and crabs) on the basalt cliffs of the northwestern shore of the island near Laguna Azul.

Isometrus, widespread tropical. Sao Tome (D. Lin phot) GG I

Basalt Cliffs near Laguna Azul, Sao Tome.  GG I  (J.Ledyard phot)

Jens Vindum confronts crab on basalt cliffs. Sao Tome.  GG I (RCD phot)

   I am told that if the new hotel project at Laguna Azul becomes a reality, the coastal area will become inaccessible to local traffic, and the road will be re-routed higher, some 3 km through the dry, north end of the island from Laguna Azul to Neves.   What we call “Shipwreck Cove” (Praia Mutamba), one of our favorite study sites and the location of some remnant dry forest will become the marina for the new hotel.  

Praia Mutamba, Sao Tome. note basalt cliffs in background. GG III (weckerphoto)

Dr. Tomio Iwamoto negotiates old dry forest. Praia Mutambo, Sao Tome GG I (RCD phot)

 Yet another example of how little we know about these islands can be found in the insect order Neuroptera.  Neuropterans are world-wide and include the lacewings, mantis flies and antlions.  As kids, we western North Americans know antlion larvae as “doodlebugs”, the little critters that form funnels in the ground. One of the world’s leading experts on the Neuroptera is the Academy’s Dr. Norm Penny,who was with us on both GG I in 2001 and GG II in 2006. 

Dr. Norm Penny with a malaise trap, Principe. GG II (D. Lin phot)

 Prior to GG I, there were only four species of neuropterans known from São Tomé and Príncipe from as many specimens. All were lacewings; antlions had never been recorded from either island.  At the end of GG I, Norm had about 370 specimens, representing 14 species in three families! 

Apochrysa  leptalea  Sao Tome. GG I (D. Lin phot)

Borniochrysa squamosa Sao Tome.  GG I (D. Lin phot)

Ceratochrysa sp.  Sao Tome. GG I (D. Lin phot)

Glenochrysa sp. Sao Tome. GG I (D. Lin phot)

The distribution of these critters throughout the Gulf of Guinea archipelago refelects an old island biogeographic principe: the number of species supportable on an oceanic island can be predicted by the island area and its distance from the mainland.  As you can see below, island area seems more important in this case. One might predict that because Príncipe is closer to the mainland, it should support more species than São Tomé. But, put simply, the larger, more variable an island’s topography, the greater number of niches (read “jobs”) are available to be filled by colonizers.

As I mentioned above, antlions (Myrmeleon) are close relatives of lacewings and had not been recorded on either island prior to GG I.  Antlion larvae dig funnel-shaped pits and hide at the bottom, partially buried in sand and waiting for an unsuspecting ant or other arthropod to slide into the pit, whereupon the larva or “doodlebug” kills and eats it. We first noticed these pits across the road from where we were staying in São Tomé in 2001. 

Antlion (doodlebug) pits. Sao Tome GG I (D. Lin phot)

antlion larva (doodlebug) exposed (J. Robinson phot)

A doodlebug lies in wait at the bottom of his pit. (WWW phot) 

Now, the curious thing is that one does not have to capture the winged adults in order to study antlions.  It turns out that the larvae are very hardy, and you only need to winkle them out of the pits, put them in a small vial of sand, and they become quiescent, surviving for long periods of time.  Norm can then raise them to adulthood later in his doodlebug lab.  

Dr. Penny in his antlion lab (note cups) (RCD phot.)

First adult Sao Tome antlion raised in lab. New record for Sao Tome. (D. Lin phot)

Norm puts the newly arrived larvae in styrfoam cups, they revive, feed on tiny crickets he provides, and then pupate. He then covers the cup, because, obviously, the adult will be winged.  We have been quite excited because we brought back the first ever Príncipe antlion larvae and one pupated in Dr. Penny’s lab.  

First Principe antlion locality. Bombom Island. GG III (weckerphoto)

Note the doodlebug has pupated.  (RCD phot)

The hatching! Note hole in the old pupa ball.  (RCD photo)

First Principe antlion hatched in our lab and a new record for Principe (RCD phot)

Very exciting.  Norm says both are species of Myrmeleon but whether they are the same species or different species has yet to be determined… This baseline work we do takes time.  But again, our job is to discover, analyze (understand) and describe.  We cannot preserve what we do not know.  

Dr. Norm Penny on Praia Agulhas, Principe. GG I (RCD phot)

Here is our usual “parting shot”: 

The “race” on Sao Tome

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.