The Urostyloidea (= urostyloids) are a group of ciliates (= Ciliophora) whose members occur in all major biotops, that is, freshwater, sea, and soil. The goal of the project was to summarise the present knowledge (supplemented by own data) about these single-celled organisms in a critical revision. The book will have about 1200 printed pages and will be published by Springer.
The classification of the hypotrichous ciliates is basically done according to the arrangement of the cirri, which are compact bundles of cilia on the ventral side of the dorso-ventrally flattened cells. The urostyloids are characterised by the zigzagging arranged ventral cirri which form the so-called midventral pattern. This pattern originates by the longitudinal arrangement of cirral pairs which are produced from oblique cirral anlagen during cell division. In the present review 32 genera comprising 148 species are considered as valid. The urostyloids are divided into four subgroups, the Holostichidae, the Bakuellidae, the Urostylidae, and the Epiclintidae.
The genus Uroleptus is also characterised by zigzagging ventral cirri. Thus, it was included in the urostyloids in previous classifications. However, molecular data suggest that Uroleptus is more closely related to other hypotrich taxa than to typical urostyloid representatives as, for example, Urostyla and Holosticha. To harmonise morphological and molecular taxonomy, we established the CEUU (Convergent Evolution of Urostylids and Uroleptids) hypothesis (Foissner et al. 2004). It suggests that the zigzagging cirral pattern evolved convergently by inserting additional anlagen between the six anlagen which belong to the ground pattern of the Hypotrichs. This hypothesis can also explain some deviating cirral patterns in other groups, for example, that of the oxytrichids Pattersoniella and Territricha. Beside molecularbiological features, the CEUU-hypothesis is supported by at last one good morphological feature (Berger 2006).
The revision should not only serve as standard for ciliatologists, but it should also be a "field guide" for limnologists, soil biologists, and marine biologists.

Berger H. (2006): Monograph of the Urostyloidea (Ciliophora, Hypotricha). Springer. More information

Foissner W., Moon-van der Staay S. Y., Moon-van der Staay G. W., Hackstein J.H.P, Krautgartner W.-D. & Berger H. (2004): Reconciling classical and molecular phylogenies in the stichotrichines (Ciliophora, Spirotrichea), including new sequences from some rare species. – Europ. J. Protistol., 40: 265-281. More information

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