Fig. 1. Hypothetical evolution of oligotrichid somatic ciliary patterns (0–IV, VI, VII, after Agatha 2011b; V, VIII–XIV, originals; protargol impregnation). Small arrows mark orientation of kineties (posterior to anterior). Arrowheads denote dorsal breaks in girdle kinety. Dotted arrows mark the tontoniid evolution. Dotted circles denote position of oral primordium in early dividers. Type 0 – dorsal kineties of hypotrich-like ancestor; Type I – strombidiid Parallelostrombidium; Type II – strombidiid Novistrombidium and tontoniid Tontonia; Type III – strombidiid Spirostrombidium; Type IV – strombidiid Omegastrombidium; Type V – strombidiid Strombidium, pelagostrombidiid Limnostrombidium, and tontoniid Pseudotontonia; Type VI – tontoniid Paratontonia; Type VII – tontoniids Laboea and Spirotontonia; Type VIII – strombidiid Foissneridium; Type IX – strombidiid Opisthostrombidium; Type X – cyrtostrombidiid Cyrtostrombidium; Type XI – strombi- diid Williophrya; Type XII – strombidiid Apostrombidium; Type XIII – hypothetic stage; Type XIV – strombidiid Varistrombidium. EX – extrusome attachment sites, GK – girdle kinety, OP – oral primordium, VK – ventral kinety.