Tintinnoinea
Geographic worldwide patterns

Scarcity of information and the overall state of disarray of the classification of marine tintinnids (see Ti. 15 Classification scheme based on morphologically similar groups of species) precludes a detailed analysis of their distribution in the South Atlantic. A few broad generalizations, however, seem possible. Table ti-Table summarizes the distribution of the 41 genera and 129 species encluded in this review (see Taxonomy in Suborder Tintinnoinea). Most of the surveys available report only presence or absence. Only a few supply quantitative species distributions (e.g., Barría de Cao, 1992; Alder, 1995). The 4 broad distributional patterns recognized are described as follows.

—Tropical and subtropical waters
Characterized by the genera Rhabdonella, Xystonella, Xystonellopsis, Epiplocylis, Climacocylis, Dadayiella, Epiplocyloides, Petalotricha, Cyttarocylis and Amphorides. These genera may be present in both neritic and oceanic waters.

—Coastal waters
The genera Codonellopsis, Codonaria, Codonella, Stylicauda, and Tintinnopsis complex are restricted almost exclusively to coastal environments; they agglutinate (mainly arenaceous) particles on their lorica (see Taxonomy, Group 1). Although tintinnids with agglutinated loricae are present at virtually all latitudes in the South Atlantic, from the tropics to the Antarctic, their abundance and diversity are highest in transitional waters. In the Bahía Blanca estuary (Argentina, ca. 39°S, 61°W), for example, the Tintinnopsis group reaches 73% of all specimens (Barría de Cao, 1992). Hyaline neritic transitional tintinnids include the genera Favella (Favella taraikaensis), Helicostomella, Eutintinnus, Metacylis, Amphorellopsis, Dictyocysta and Clevea?

—Subantarctic waters
Characterized by Acanthostomella, Steenstrupiella, Cymatocylis antarctica, Eutintinnus rugosus and Codonellopsis pusilla, all of them inhabiting both neritic and oceanic areas.

—Antarctic waters
Characterized by the genera Laackmanniella and Codonellopsis (see Biogeographic Zonation, Antarctic Oceanic below) which, together with Cymatocylis, are here the most abundant tintinnids. It should be noted that the Tintinnopsis complex, widely distributed elsewhere, is absent from the Southern Ocean.

Some tintinnid species characteristic of a given area may often be found outside its boundaries: Cymatocylis convallaria, forma affinis and Laackmanniella naviculaefera, forma naviculaefera, typically Antarctic taxa, have been recorded also in subantarctic waters; transitional species, such as Dictyocysta elegans, were found in typically Antarctic waters; the tropical species Ascampbelliella armilla, Brandtiella palliata and Xystonellopsis paradoxa have been recorded also in the Subtropical Convergence. This expatriation, attributable to advection by surface or deep currents and subsequent resurfacing, or to entrainment in eddies, is very common in tintinnids.

As shown in worldwide distribution, although North Atlantic tintinnids have been intensively studied, large sectors of the South Atlantic (especially the Central Gyre and the subantarctic latitudes) still remain virtually unknown. Neritic zones have been more intensively surveyed in the Southwestern Atlantic than off the African coast. According to Pierce and Turner (1993), the 53 tintinnid genera recognized in the World Ocean can be grouped into six overall distribution patterns: warm water (43.4%); cosmopolitan (30.2%); neritic (13.2%); boreal and austral (3.8% each); and endemic tropical Pacific (5.6%). The authors point out that the tropical Pacific differs from other oceans in that it hosts three endemic genera: Amplectellopsis, Cricundella and Codonopsis. However, the former two were synonymized with genus Amplectella (for illustrations see species listed for genus) by Balech (1975), a genus well-represented in deep-sea layers of the Atlantic; while the systematic position of Codonopsis is dubious, and it includes the single species Codonopsis olulla (C. sp. aff. C. olla), originally described by Brandt (1906-1907) in the genus Cyttarocylis and very rarely found thereafter. Thus, with the exception of the Indian Ocean, the largest oceanic areas of the world host practically identical generic assemblages. Available specific information is scarce and contradictory, and does not permit precise identification of endemic species.