Fig. 4

Morphology of Frontonia paravernalis sp. nov (Italian population - IPSal + sm). a Schematic drawing of the ventral side; b live cell bearing Chlorella-like (Ch) endosymbiotic algae; c nuclear apparatus after Feulgen stainining, showing the macronucleus (Ma), several micronuclei (Mi) and the old macronuclear fragments (MaF); d closer view of Ma and “compact type” Mi after Feulgen staining; e detail of Mi morphology and location in living condition; f detail of trichocysts (Tc) in living cell; g closer view of contractile vacuoles (CV) and collecting canals (CC); h detail of the single pore of contractile vacuole (PCV) in living condition; i detail of Chlorella-like endosymbionts (Ch) after F. paravernalis cell disruption. CC – collecting canals; Ch – Chlorella-like endosymbiont; CV – contractile vacuole; Ma – macronucleus; MaF – macronuclear fragment; Mi – micronucleus; OA – oral aperture; P – phagosomes; PCV – pore of contractile vacuole; PrS – preoral suture, PtS – postoral suture; Tc – trichocysts. Bars stand for 50 μm (a-c), 20 μm (f-h), 10 μm (d, i), 5 μm (e)