Soil Ciliates (Protozoa, Ciliophora) from Namibia (Southwest Africa) with Emphasis on Two Contrasting Environments, the Etosha Region and the Namib Desert

• Description

A highly diverse ciliate community was found in 73 samples from terrestrial and semiterrestrial habitats of Namibia, Southwest Africa, one of the world's driest countries. The ciliate, respectively, their resting cysts, were re-activated from air-dried samples using the non-flooded Petri dish method. Species were determined by combining live observations, silver impregnation, and scanning electron microscopy.

A total of 365 species were identified, of which 128 (35%) were undescribed, including a new order and suborder, three new families, and 34 new genera and subgenera. These new and many insufficiently known taxa, altogether more than 200 species and subspecies and over 300 populations, are described in the present monograph (see chapter 3.2.1 for a summary of names and nomenclatural acts); 800 type slides have been deposited in (LI). Further, ontogenesis was investigated in 20 species. The Namibian soil ciliate community shows some remarkable differences to the world community. Specifically, raptorious gymnostomatids and filamentous cyanobacteria feeding nassulids are over-represented, while hypotrichs and peritrichs are underrepresented. Nassulids obviously profit from the cyanobacteria covering wide areas of the Etosha region and the crust soils in the arid areas. Hypotrichs are more k- than r-selected and thus cannot develop optimally in the harsh Namibian climate. Likewise, the sandy soils are disadvantageous for sessile peritrichs. Generally, however, the Namibian soil ciliate biota are unexpectedly rich, that is, more diverse than those from central Europe, likely because they had at least 55 million years to evolve adapted populations and species.