Classification and distribution of South Atlantic Recent polycystine Radiolaria

Abstract

This paper presents a review of the current knowledge on the identification and distribution of Recent polycystine Radiolaria so far recorded, or presumed to occur, in the South Atlantic Ocean (0° to 60°S, from the South American coasts to the coasts of Africa). However, because the area concerned covers from equatorial to Antarctic waters, and since polycystine radiolarians are geographically (but not environmentally) cosmopolitan, the review covers most common species worldwide. Illustrations, short diagnoses, bibliographic references and distributional data (both geographic and vertical) are included for 164 polycystine morphotypes (species-groups, species, and subspecific categories). Introductory remarks offer general data on radiolarian anatomy, biology, ecology, and reproduction. Methodological aspects are dealt with in some detail, with special emphasis being placed on comparative aspects of the environmental and paleoenvironmental information conveyed by planktonic materials, sediment trap samples, and sedimentary deposits. Known or assumed geographic and vertical species-specific distribution ranges are summarized, as well as available information on absolute abundances in the water-column (plankton and sediment trap samples) and in the surface sediments. The illustrated glossary aimed at the less experienced student defines the terms and morphological details useful for diagnostic purposes.