Soil ciliates from Namibia (Southwest Africa) with special regard to the Etosha Pan: a contribution to tropical protozoan biodiversity

Ciliates are single-celled organisms ("Protozoa") inhabiting a great variety of biotopes. Those living in soil have been very poorly studied, especially in the tropics. In 1994 1 financed privately an expedition to one of the most interesting and nice places on the earth, the Etosha Pan in Namibia (Southwest Africa), to collect soil samples along two transects and from several special habitats. A preliminary analysis of 12 samples showed that they were inhabited by 150 species of ciliates, 50 (!) of which were new to science. Obviously, the Etosha Pan is a ,`Biodiversity Centre" as concerns soil ciliates. The research objectives and perspectives of the proposed project can be summarized- as follows: 0to obtain reliable information on soil ciliates from tropical Africa, especially from the ,`biodiversity centre" Etosha Pan; 0to describe the many new species discovered in the pilot study and those to be expected when the rest of the samples (40 all together) will be investigated; 0the Etosha Pan then will be the locus classicus of many new ciliate species which could provide further reasons for its protection, especially of the highly saline pan centre, which is often considered as useless; 0to obtain information on geographical distribution and endemism of soil ciliates; 0to educate young scientists in biodiversity studies and taxonomy of ciliates. The results will be published as individual papers in scientific journals and as a summary in a book (we already have a publisher). We have great experience in studying soil ciliates and my laboratory is in this respect unique worldwide. The project is planed for three years, and the financial support needed amounts to about 3 million Austrian shillings, mainly to finance a full-day post-doc, a graduate student, and a half-day technician.

Biodiversity and geographical distribution of soil ciliates (Protozoa, Ciliophora) from Namibia (southwest Africa) were investigated. 380 taxa were identified, of which the enormous number of 136 were undescribed, showing that there are much more ciliate species than the 3000 supposed by Finlay and Fenchel. Further, many of these new species likely have a restricted geographical distribution. One new order, one new suborder, three new families, 26 new genera, and 6 new subgenera were established for a proper classification of the new species found. Our study is the most detailed and comprehensive investigation ever has been made on ciliates from a certain biotope and country, and is thus of central importance of future biodiversity studies. 73 samples were taken from a great variety of terrestrial biotopes with special interest in the Namib Desert and the Etosha Pan, whose soil is a peculiar mixture of salt, clay, and lime showing a steep increase in pH (~7.0 9.0) and salinity (0 50) horizontally and vertically. The air-dried soil samples were put in a Petri dish and saturated, but not flooded, with distilled water. The ciliate species developed were determined from life, after silver impregnation (to reveal the ciliary pattern and nuclear apparatus), and scanning electron microscopy. A conservative species concept was applied, that is, new species were classified as such only when populations could be separated from their relatives by at least one distinct morphological feature. The morphology of 225 new or poorly known species, and cell division (ontogenesis) of 16 "difficult" species were thoroughly investigated, described and illustrated by about 3500 line drawings and 2350 micrographs. The faunistic lists provided information about the geographical distribution of the ciliate species. Some of the findings have been published in peer-reviewed journals, while the main part, that is, the description of the 225 species mentioned above, is in press as a book (1500 pages in English; "Denisia" series of the Oberösterreichische Landesmuseum in Linz). Considerable biodiversity was found in the saline soils of the Etosha Pan, where nearly half of the species were undescribed. Although there was a clear tendency that the percentage of new, probably a-selected species increased with salinity and pH, the soil microstructure and plant community also influenced the ciliate assemblage. Compared to the Etosha Pan, the Namib Desert contained "only" 13 new species, but most are likely restricted to this area. The richest sample was from road puddles near the Bambatsi Guest Farm in the Mopane savannah at the Namib Escarpment. It contained 141 species, of which circa 34 were undescribed. The discovery of so many new species and the re-discovery of several poorly known species in the Etosha Pan, often considered as useless, provide strong reasons for its protection. Samples were collected with permit from the Namibian Ministry of Wildlife, Conservation, and Tourism.