Optical micrographs of Tetrakeronopsis silvanetoi after protargol-impregnation.

A. Holotype specimen viewed from dorsal side, showing the disposition of nuclear figure; B. Detail of nuclear apparatus shown from ventral side; C. Specimen showing macronuclear DNA replication bands (arrowheads); D. Proter of a late divider. Arrowheads show fronto-ventral set of juvenile cirri; E. Dorsal side of late divider opisthe showing juvenile dorsal kineties (arrowheads); F. Late divider showing morphogenesis of nuclear apparatus. Black arrowhead points to dividing micronucleus; white arrowheads show dividing macronuclei; G. Ventral side of reorganizer. Arrowheads indicate newly formed transverse cirri. Legend: AZMp – adoral zone (of membranelles) of proter; AZMr – adoral zone (of membranelles) of reorganizer; FTCp – frontoterminal cirri of proter; FTCr – frontoterminal cirri of reorganizer; LMRp – left marginal cirral row of proter; LMRr – left marginal row of reorganizer; Ma – macronuclear nodules; Mi – micronucleus; PTCr – pretransverse cirri of reorganizer; RMRp – right marginal cirral row of proter; RMRr – right marginal cirral row of reorganizer. Scale bars: A. 100 µm; B–D., G. 20 µm.