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A
view of the islands
The
cocoa islands as known in the past are located just north of the Ecuatorian
line, north is found Bioko a former Spanish colony (Fernando Poo), now
Equatorial Guinea, and south the tiny island of Annobon, belonging to
this same country. These are heavily mountainous islands of volcanic
origin, covered still in pristine forests.
The
Democratic Republic of Sao Tome and Principe is the official name of
the country these two small islands share today, their background as
of all these new countries is colonial, Spanish and later Portuguese
settled down here attracted to the immense natural resources of the
area. Unhabited, (unlike Bioko that was home to ethnic groups as the
Bubas etc...) slaves were taken from the mainland to work. Cocoa and
copra were the main products of the different plantations founded there,
and even today, many villages keep the former names given to these Roças,
to say large orchards, that were the islands.
Great
colonial manors are to be found all around, many eaten by the jungle
and forgot, but a hope for the expected turistic future. Today the prices
of cocoa and copra have dropped and the only profitable item is coffee
as an export good, fishing is practiced in a low scale mainly for personal
use although rich is their sea in quantity and species, major factories
are unexistant, in fact most of the goodies are brought from Portugal.
As
happened in all these former colonies the zoological/botanical diversity
was researched during the 18th and 19th century the most, rich owners
of plantations were amused to receive and help different famous scientists
of their times; Exell for example as botanist, and F.Newton, Fea, Rang,
Dohrn and Greeff among others were the first ones to classify and show
the world the malacological wonders of this area.
Anyone
may wonder how was it possible in their times to make such a magnificient
accounts of their travels and findings, specially F.Newton was specially
metticulous and his collections had the best locality/ecological datas
of the time. Others as Fea were not so clear and many of the species
found are still lost.
No
doubt there is a great debt of admiration and gratitude towards all
these fearless travellers that sailing around, discovered and described
what was to be found in the further hidden corners of their, by then,
inmense world. They illuminated the minds and dreams of generations
of scholars and nature lovers. They gave a value for things that in
those times were taken as granted; it is possible that thanks to them
all this marvels are still with us, or sadly some times their accounts
are the only way to know about extinct plants and animals or seeing,
through their eyes, the pristine state of nature they encountered all
over.
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A
malacological portrait
Unlike
all these oceanic islands (as Madeira or the Canaries) the number of endemic
landsnail species found in this area is low..... most of the genuses are
shared with the other islands and the mainland. The most important thing
in a malacological point of view is the existance of an own family: Thyrophorellidae
(more research is done in this field and soon we will be able to know
if this family is going to stay), with just one known species: Thyrophorella
thomensis (Greeff).
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as Achatinidae are well represented as in all this African ecuatorial
area. Archachatina bicarinata is the larger endemic (Being introduced
Archachatina marginata), scientist are not sure of the original
island where this species evolved as due to human interactions it is now
found in both , I anyway I try to think it is Sao Tome, as the other island
curiosity of the other island, Principe, the endemic genus Columna
lives in the same kind of habitat being I think difficult sharing the
same resources. It is interesting to know that all these species are normally
sinistral being this an extraordinary event not so often seen in this
family. As the former species where ground dwellers, there are also a
few species adapted to arboreal conditions. Lignus alabaster and
Atopocochlis exaratus; both have when immature emerald green coloured
organs, allowing to see this colour through their translucent shell. Also
Streptaxids, many Helicarionidae as Thomeonanina hepatizon and
Thomeonanina welwitschi, a diversity of uncommonly shaped and sized
Subulinidae as Bocageia massoni, covered with a periostracums showing
rows of hairs, Bocageia clava, and Bocageia monticola ,besides
a couple of prosobranchs of the family Maizanidae.
The
size of the snails here also is remarcably larger compared to the minute
Bioko/ Annobon species (overall, not just Achatinidae), and there are
many curious adaptations as thick hairy periostracum covers that make
the animals almost not visible in their enviroment to predators (included
passionate collectors)..
The
main problem for locating colonies of the endemic species is finding the
original forest covers, where the human action has not been perceived,
as many plantations are now closed there are often deep forests all around
but until the 60's all these areas were heavily farmed, someone visits
such places with good expectations to find species and you are most likely
to found just A.marginata as everywhere.
The
actual situation of these islands malacofauna is good although as the
use of the land is changing, species that found shelter in plantations
are being driven away and nothing is known about their former distribution
, for example Archachatina bicarinata was in the past found all
around both islands now colonies are just restricted to the southern and
higher mountain areas, more humid and better for them as new crops are
being tried for their dislike, the introduced Archachatina marginata
has been taking all these drier sites and now is widespread. The higher
mountains are supposed to be the last home to many unknown species, much
more work is needed to understand the different chains that form these
islands.
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