Bad News for Brazilian Land Snails
by Jose Coltro
During the last eighty or ninety years, Brazilian land shells have been almost forgotten by most biologists and collectors. Abbott listed most of them as "extinct" in his Compendium of Landshells. Since the 1910 papers by von Ihering, or even before, with Pilsbry's work, the studies on many species were done through an occasional expedition to the Atlantic Rain Forest - probably the richest forest in the world.
When the Portuguese arrived in Brazil, in 1500, almost all the Brazilian coast from Rio Grande do Norte to Rio Grande do Sul were densely covered by an incredible forest. There they found a tree that they called "pau-brasil" (pau=wood, brasil=fire) and they used this name for the new land. The trees were perfect for boats and to produce a kind of pigment. Immediately the Portuguese and others (especially French pirates) started to export large quantities of this "pau-brasil," plus mahogany, jacaranda, and others. It was the beginning of the destruction of the Atlantic Forest. In the 1500's the Portuguese colonization brought thousands of people for agriculture. They planted sugar cane widely all along the coast and took down more of the forest. In the next centuries others crop -- coffee or corn, even wood exportation -- destroyed more than 2 million square kilometers of this rich forest.
Today less than half million square kilometers resist man's destruction. Most of this forest was preserved in state parks in Sao Paulo State and in large cacao farms in Bahia State.
Bahia is the most important landshell province in all Brasil, and one of the richest in the world. There are a large number of species, most of them in plentiful in terms of specimens. But since the beginning of this century, species like Neobeliscus calcarius (Born, 1778) and Polygyratia polygyrata (Born, 1778) have not been found. In 1990 we decided to try to explore some cacao farms and we found a live specimen of the "extinct" Obeliscus obeliscus (Moricand, 1833). On the following year we sent an expedition to this area; our people were able to find a large quantity of the "extinct" species after decades of their being unobtainable to collectors worldwide. We sent specimens also to two of the best Brazilian Malacological Museums - our National Museum, in Rio de Janeiro, and the Zoological Museum of the University of Sao Paulo. Finally the anatomy of most of these species was studied. We felt they were securely protected because most of these species live in forest that protects the cacao farms. The cacao tree needs a lot of shade to produce the fruits, so farmers try to protect the natural forest to provide this shade.
But since last year a plague has been attacking the cacao tree - the local farmers call it "vassoura de bruxa" ("witch broom"), a fungus that destroys the tree; there are no easy treatments for it, except to cut the tree! Large number of farms are losing the cacao trees and farmers have begun exchanging cacao culture for that of bananas or sugar cane. The original forest that protects the cacao, and the flora and fauna besides, is being cut down every day.
Some of our people are not finding many of the good spots for collecting now - where they found a wonderful forest two years ago, now they encounter only sugar cane or bananas. Even worse, the area has been treated by agricultural poisons to protect the new crops and thousands of dead shells were found, no live ones!
The Brazilian government is setting scientists to the task of eliminating this plague, so that the cacao culture can maintain this part of Brasil as a nice link between man and nature. If the cacao trees disappear, the interdependence of the forest and the cacao crop will vanish too, new crops will continue to be planted and the forest will no longer be needed. About 5 million people live in this area -- most of them owe their survival to this cacao crop. To solve their social problem the farmers will have to choose between a new crop or the forest. The government knows that it is very important to keep the forest, but they also know that they have to help the people who live in this area. If in these next few years a solution does not appear, the forest will disappear and Abbott will be right to use "extinct" for these species.