Biotic interaction between spionid polychaetes and bouchardiid brachiopods: Paleoecological, taphonomic and evolutionary implications

Shells of Bouchardia rosea (Brachiopoda, Rhynchonelliformea) are abundant in Late Holocene death assemblages of the Ubatuba Bight, Brazil, SW Atlantic. This genus is also known from multiple localities in the Cenozoic fossil record of South America. A total of 1211 valves of B. rosea, 2086 shells of sympatric bivalve mollusks (14 nearshore localities ranging in depth from 0 to 30 m), 80 shells of Bouchardia zitteli, San Julián Formation, Paleogene, Argentina, and 135 shells of Bouchardia transplatina, Camacho Formation, Neogene, Uruguay were examined for bioerosion traces. All examined bouchardiid shells represent shallow-water, subtropical marine settings. Out of 1211 brachiopod shells of B. rosea, 1201 represent dead individuals. A total of 149 dead specimens displayed polychaete traces (Caulostrepsis). Live polychaetes were found inside Caulostrepsis borings in 10 life-collected brachiopods, indicating a syn-vivo interaction (Caulostrepsis traces in dead shells of B. rosea were always empty). The long and coiled peristomial palps, large chaetae on both sides of the 5th segment, and flanged pygidium found in the polychaetes are characteristic of the polychaete genus Polydora (Spionidae). The fact that 100% of the Caulostrepsis found in living brachiopods were still inhabited by the trace-making spionids, whereas none was found in dead hosts, implies active biotic interaction between the two living organisms rather than colonization of dead brachiopod shells. The absence of blisters, the lack of valve/site stereotypy, and the fact that tubes open only externally are all suggestive of a commensal relationship. These data document a new host group (bouchardiid rhynchonelliform brachiopods) with which spionids can interact (interestingly, spionid-infested sympatric bivalves have not been found in the study area despite extensive sampling). The syn-vivo interaction indicates that substantial bioerosion may occur when the host is alive. Thus, the presence of such bioerosion traces on fossil shells need not imply a prolonged post-mortem exposure of shells on the sea floor. Also, none of the Paleogene and Neogene Bouchardia species included any ichnological evidence for spionid infestation. This indicates that the Spionidae/ Bouchardia association may be geologically young, although the lack of older records may also reflect limited sampling and/or taphonomic biases.

The outlook for agriculture and rural development in the Americas: a perspective on Latin America and the Caribbean, 2010

Includes Bibliography

Gestión social: cómo lograr eficiencia e impacto en las políticas sociales

Incluye Bibliografía

Recent trade performance of Caribbean countries

Includes bibliography

Growth versus development: different patterns of industrial growth in Latin America during the 'boom' years

Includes bibliography

Productivity growth in Latin American manufacturing: what role for international trade intensities?

Includes Bibliography

Regional interdependencies and macroeconomic crises: notes on MERCOSUR

Includes bibliography

Los regímenes de la inversión extranjera directa y sus regulaciones ambientales en México y Chile

Incluye Bibliografía

Mejores prácticas en materia de defensa de la competencia en Argentina y Brasil: aspectos útiles para Centroamérica

Incluye Bibliografía

Antidumping and the global financial crisis: the impact on Latin America and the Caribbean

Includes bibliography

Fertility and female labour supply in Latin America: new causal evidence

Includes bibliography

Situación y perspectivas de la minería metálica en Argentina

Incluye Bibliografía

Políticas e instituciones para el desarrollo económico territorial. El caso de Argentina

Incluye Bibliografía

How optimal are the extremes?: Latin American exchange rate policies during the Asian crisis

Includes bibliography

Reconfigurando la canción, reinventando la nación: La folclorización de la música popular en brasil y en chile en los años cuarenta y cincuenta

At the middle of the twentieth century, between the forties and the fi fties, especially after the Second World War, the endless debate concerning national identity was taken up again in Latin America with a new focus. Mass culture, especially popular music with ties to the music industry, was shaped by its great capacity to spreadshown through its assorted forms of production, circulation and consumption- as one of the main areas of dispute related to the question of what is considered to be national. During that period there were important debates in Brazil and Chile about the selection, preservation and perpetuation of a certain repertoire of popular urban music as being representative of national folk music. These debates, which are analyzed starting from discursive representations driven by the written press, in both the specialized academic and the large-circulation press, constitute the central focus of this article.