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Biodiversity in Latin America E-mail
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Written by Administrator   
Tuesday, 19 June 2007
Biodiversity in Latin America

EARTHWORM BIODIVERSITY IN LATIN AMERICA: PRESENT STATE OF THE ART

 George G. Brown1, Carlos Fragoso2 and Samuel W. James3

1Embrapa Soybean, C.P. 231, Londrina, PR, 86.001-970, Brazil;

2Instituto de Ecología, A.C., A.P. 63, Xalapa, VER., 91000, Mexico;

3Natural History Museum & Biodiversity Research Center, University of Kansas, Lawrence, KS, 66045, USA.

Around 970 species of earthworms, belonging to 11 families and 125 genera are known from Latin America (LA), although this is less than half the total estimated diversity for the region (>2500 spp.). The most diverse countries are Brazil (306 spp., 260 natives), Ecuador (136 spp., 113 natives), Mexico (133 spp., 83 natives) and Colombia (116 spp., 93 natives). The Caribbean Islands host more than 120 species, of which 95 are native. However, the status of the knowledge on earthworm diversity and ecology in most countries must still be considered poor. For large areas of some countries and several islands in the Caribbean, still nothing is known. Most of the knowledge of the earthworms in LA is due to the work of Gilberto Righi, who described over 220 spp. Other taxonomists (Michaelsen, Cernosvitov, Cognetti, Rosa, Eisen, Beddard, Benham, Cordero, Gates, Sims, Graff, Zicsi, Csuzdi, Fragoso, James, Rodriguez, Borges, Moreno, Jamieson) also contributed greatly to the knowledge of the region’s earthworm diversity.

Most of the known (and still unknown) species belong to the Glossoscolecidae family (533 spp.), endemic to LA, and found from Northern Argentina to Central Mexico (native species range). This family is unique in its multiform manners of reproduction, some of which still remain unknown (e.g., Glossoscolex). Other diversified families include the Acanthodrilidae (269 spp. in 26 genera) and Ocnerodrilidae (91 spp. in 26 genera), that also include many endemic genera and species. One family is endemic to Colombia (Tumakidae).

Exotic species (total ~70 spp.) are common and widespread throughout the region, although the Lumbricidae are mostly restricted to cooler regions. Acanthodrilids such as some Dichogaster spp. and megascolecids such as Amynthas spp. are found in all tropical regions of LA. Some native species have spread widely throughout LA and must be considered peregrine or exotic invaders outside their native range and place of origin. This is the case for Pontoscolex corethrurus, native to the Guyanan Shield, but invasive throughout the tropics and subtropics. Several ocnerodrilids (especially Eukerria spp.) and acanthodrilids (especially Microscolex spp.) also fit in this category. Strategies to curb the spread of exotic species should be studied and adopted to minimize their potential impacts to soils, plants and other organisms. Urgent efforts are also needed to speed descriptions of native earthworms and to promote the study of their biology and ecology, as most studies so far have been performed on exotic or peregrine native earthworm species (very little is known for the vast majority of native species). Given the few trained earthworm taxonomists and ecologists available in LA, the increasing trend in urbanization, intensification of agriculture and pressure on natural resources and native habitats (especially forests and grasslands) throughout LA, this enormous task is daunting!

 
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