Divisional morphogenesis in Uroleptus caudatus (Stokes, 1886), and the relationship between the Urostylidae and the Parakahliellidae, Oxytrichidae, and Orthoamphisiellidae on the basis of morphogenetic processes (Ciliophora, Hypotrichida).

Morphogenetic processes during division in Uroleptus caudatus (Stokes, 1886) are described using protargol impregnation. As is typical for the family Urostylidae Bütschli, 1889, zigzag midventral cirri develop, but contrary to most species of this family the adoral membranelles of the proter are not renewed during division and two dorsomarginal kineties develop. These two atypical features occur in only two other species of the Urostylidae (Uroleptus musculus, Holosticha diademata), and in all species of the family Parakahliellidae Eigner. 1997, and in many of the Oxytrichidae Ehrenberg, 1838. Membranelles are also not renewed in the Orthoamphisiellidae Eigner, 1997. This shows that these three atypical members of the family Urostylidae are those which are most closely related to the other three hypotrichous families named above. The highly distinct zigzag midventral cirri clearly separate the family Urostylidae from the other three hypotrichous families. These cirri are used together with new morphogenetic features for a revised family diagnosis. The analysis of the Urostylidae revealed that during division all species of the family Urostylidae develop their cirral patterns, including the two rightmost ventral anlagen, in separate areas for each proter and opisthe. Thus, "long primary primordia" are absent in the Urostylidae. This is similar to the morphogenetic pattern by which the family Parakahliellidae is defined ("neokinetal 1") indicating that the Urostylidae are more closely related to the Parakahliellidae than to either the Oxytrichidae or to the Orthoamphisiellidae. All 68 detailed descriptions of divisional morphogenesis in species of the Hypotrichida are analyzed now in this and two former papers. As a result all these species can be assigned or at least recognized to be closely related to one of the following four families: to the Orthoamphisiellidae ("within-row" anlagen), to the Oxytrichidae ("neokinetal 3" anlagen), to the Parakahliellidae ("neokinetal 1" anlagen), and to the distinctly different Urostylidae ("midventral" anlagen). Thus, all Hypotrichida can most probably be assigned after morphogenetic investigation to one of the four families.

Divisional morphogenesis in Bakuella pampinaria nov. spec, and reevaluation of the classification of the urostylids (ciliophora, hypotrichida).

A new hypotrichous ciliare, Bakuella pampinaria nov. spec, colonizing vineleaf and pear-tree litter, is described. Bakuella pampinaria differs from the other species of the genus by having distinct rows of yellowish cortical granules. Several morphogenetic differences separate Bakuella pampinaria from Bakuella edaphoni and other congeners, especially in that the transverse cirri do not participate in the formation of the oral primordium. The type population of Pseudourostyla cristata was reinvestigated. Two frontoterminal cirri are recognizable in dividing specimens indicating that this genus is valid, i.e. different from Urostyla, which very likely lacks such cirri. The urostyline hypotrichs are recognized as a monophyletic taxon by two apomorphies, viz. the midventral cirri and the partial or complete reorganization of the proter's adorai zone of membranelies during cell division. Phylogeny and evolution within the urostylids are much less clear since character states (apomorphies, plesiomorphies, convergencies) are uncertain and morphogenetic data are still too sparse or inaccurate. This is exemplified on a selected set of genera using Hennig's phylogenetic method.