Photomicrographs of <i>Apoamphisiella vernalis</i> from Minad Gerais after protargol-impregnation, showing stages of divisional morphogenesis.

<p>(A) and (B) Ventral side of middle-to-late divider showing anlagen for proter (A) and opisthe (B). Arrowheads mark surplus transverse cirri in the proter (notice that surplus transverse cirri are also present in the opisthe, but out of focus in the image). (C) Middle divider showing dorsal kineties anlagen for the proter (white arrowheads) and opisthe (black arrowheads). (D) Fragmentation of right dorsal anlagen (arrows) and formation of caudal cirri (arrowheads). Anlagen labeled with roman numbers, where “o” names the opisthe and “p” names the proter.</p

Photomicrograhps of <i>Apoamphisiella vernalis</i>, from life with DIC (A, D, E) and bright field (B, C).

<p>(A) Cortical granules on dorsal side of body. Arrowheads show dorsal bristles. (B) Clusters of cortical granules near caudal cirri (arrowheads). (C) Aculeate crystals of specimen from a mineral water culture, after cell rupture. (D, E) Cytoplasmic crystals (arrowheads) inside specimens from raw samples of Tucunduba river (D) and from a ruptured cell from a culture made with mineral water (E); black arrowheads show lipid droplets, white arrowheads mark aculeate crystals, and arrow shows a polygonal crystal. Scale bars: 10 μm.</p

Photomicrograhps of postdividers of <i>Apoamphisiella vernalis</i>, after protargol-impregnation.

<p>(A) Ventral side of proter postdivider. Black arrowhead points to terminus of left marginal row. White and black arrows show parental left and right marginal cirri, respectively. (B) Ventral side of opisthe postdivider. Black arrowhead shows postperistomal cirrus, which did not yet reach its final position behind buccal vertex. White arrowhead shows parental transverse cirri. White and black arrows show parental left and right marginal cirri, respectively. (C) Dorsal side of specimen from A, with black arrowhead showing terminus of left marginal row. (D) Dorsal side of specimen from B. Asterisks in C and D mark scattered dikinetids between dorsal kineties 3 and 4, possibly resulting of late multiple fragmentation of rightmost dorsal anlage. CC = caudal cirri; DK(n) = dorsal kinety.</p

Photomicrograhps of <i>Apoamphisiella vernalis</i> after protargol-impregnation, showing stages of divisional morphogenesis of ventral side.

<p>(A) Opisthe of middle divider showing left (white asterisk) and right (black asterisk) marginal rows anlagen and dorsomarginal kineties anlagen (arrow). (B) Detail of juvenile dorsomarginal kineties (arrow) of opisthe. (C) Proter of late divider showing juvenile fronto-ventral-transverse cirri linked according to anlagen. Black arrowhead shows transverse cirrus formed by extra anlage. (D) Late divider showing distribution of juvenile macronuclear nodules in proter (white asterisks) and opisthe (black asterisks). Ma = macronuclear nodule; Mi = micronucleus.</p

Diagram showing homologies among ventral cirri of <i>Cyrtohymena</i>, European and North American <i>Paraurostyla weissei</i>, and <i>Apoamphisiella</i> on stylized drawings.

<p>*The rightmost ventral cirral row of European <i>P</i>. <i>weissei</i> corresponds to the posterior segment of an amphisiellid row. Fronto-ventral-transverse anlagen are numbered in romans. IV_? = anlage supposedly related to IV; V_i … V_j = serial homology of anlage V, where “i” is the leftmost and “j” the rightmost in the series; aAR = anterior segment of the amphisiellid cirral row; B = buccal; F = frontal; FV = frontoventral; Pp = postperistomal; PT = pretransverse; T = transverse; VR = ventral cirral row; - = inapplicable.</p

Uncorrected <i>P</i>-distances among the terminals in the cluster of the “non-stylonychine dorsomarginalians” in which <i>A</i>. <i>vernalis</i> was placed.

<p>Uncorrected <i>P</i>-distances among the terminals in the cluster of the “non-stylonychine dorsomarginalians” in which <i>A</i>. <i>vernalis</i> was placed.</p

Morphometric data on <i>Apoamphisiella vernalis</i> from Belém-PA, Brazil.

<p>Morphometric data on <i>Apoamphisiella vernalis</i> from Belém-PA, Brazil.</p

Bayesian inference (50% majority rule consensus) tree of Hypotricha, emphasizing the relationships within the Dorsomarginalia (uroleptids, stylonychines and “non-stylonychine dorsomarginalians”) and some <i>incertae sedis</i> representatives.

<p>Values associated to nodes are Bayesian posterior probabilities / maximum-likelihood bootstrap support. * = full support; ? = node contradicted in the maximum-likelihood tree. Scale bar = substitutions per 100 nucleotide positions.</p

Scanning electron micrographs of <i>Apoamphisiella vernalis</i> on dorsal side.

<p>(A) Anterior region. Black arrowhead points to dorsomarginal kinety with relatively wider-spaced kinetosomes, thus possibly a retained parental structure. White arrowheads show typical dorsomarginal kineties. (B) Posterior region. Asterisks mark spaced dorsal bristles, possibly parental structures, at the field of scattered dikinetids. (C) Specimen with one dorsal bristle (white asterisk) between dorsal kineties 3 and 4. Black asterisk marks kinety 4. (D) Anterior region of specimen with three typical dorsomarginal kineties (arrowheads). (E) Detail of dorsal dikinetid showing that anterior basal body is ciliated. (F) Detail of caudal cirri to show barren basal bodies (arrowheads). Scale bars: A, B, D. 10 μm; F. 3 μm.</p

Diagrammatic representations of protargol-impregnated specimens of <i>Apoamphisiella vernalis</i> showing stages of divisional morphogenesis.

<p>(A) Ventral side of middle divider. White arrowhead shows left frontal cirrus segregating from undulating membranes anlage; black arrowheads show formation of transverse cirrus by each of the extra anlagen of proter and opisthe; white and black asterisks mark left and right marginal rows anlagen, respectively, for proter and opisthe. Dorsomarginal anlagen shown by arrows. The double arrowhead shows macronuclear nodules fused into a single mass. (B) Dorsal side of same divider, showing juvenile caudal cirri of proter (white arrowheads) and opisthe (black arrowheads), fragmentation of rightmost dorsal anlage (arrows), and dividing macronucleus and micronuclei. E = endoral; Ma = macronucleus; Mi = micronucleus; P = paroral. Scale bars: 50 μm.</p