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Bromeliads are mainly epiphytic rosette plants occurring only in Central and South America. They collect rain water and particulate materials in tanks (cisterns) formed by the coalescing leaf axils. These tanks form an extensive, highly compartmentalized water and humus body above the ground and are inhabited by many ordinary and endemic organisms. We discovered at least 10 new ciliate species in the tanks of about 15 bromelian species from the Dominican Republic, Ecuador, and Brazil. Since there are 2000–3000 bromelian species with very different lifestyles, they are likely to contain hundreds of novel ciliate species. Two of the new species described here are real “flagships”, that is, they have such a large size that they would have been found in Europe, if they were there. Consequently, these species must have a restricted geographical distribution, disproving the old hypothesis that microscopic organisms are cosmopolitan. Also the smaller ciliates described here represent new genera and families, arguing for a long-lasting, independent evolution driven by ecological constraints and spatial isolation. Almost half of the new species can switch from bacteriophagous, microstome morphs to a predatory, macrostome lifestyle, likely due to the strong competition in these peculiar habitats. The high morphological and ecological diversity of tank bromeliad ciliates is only partially recovered by small-subunit (18S) ribosomal RNA (rRNA) gene sequences. |
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