Fig. 3

a–h Early and middle stages of morphogenesis in Parasincirra sinica n. sp. after protargol staining. a, b Ventral views of early dividers, showing oral primordium of opisthe and frontoventral-transverse cirral anlagen. Note parental undulating membranes start to dedifferentiate (b). c, d Ventral views of later dividers, to show the development of oral primordium, frontoventral-transverse cirral anlagen and undulating membranes anlagen (arrows). Note the dedifferentiation of membranelles at the proximal end of the old adoral zone of membranelles (arrow in c), and the intrakinetally formed anlagen for the marginal rows (d). e–h Ventral (e, g) and dorsal (f, h) views of middle dividers, to show stretched marginal anlagen and dorsal kineties anlagen, the posterior membranelles of the parental adoral zone of membranelles renewed (g) and the macronuclear nodules fusing into a single mass. Note the old dorsal dikinetids are not absorbed (arrows). OP oral primordium, LMA left marginal anlagen, Ma macronuclear nodules, Mi micronuclei, RMA right marginal anlagen, 1–3 dorsal kineties anlagen 1–3. Scale bars: a, g, h = 60 μm. The images of this figure we have used are freely available to use