Taxonomic and Morphogenetic Description of the Freshwater Ciliate Aponotohymena isoaustralis n. sp. (Ciliophora; Oxytrichidae) Isolated from Sanjay Lake, Delhi, India Author Gupta, Renu Author Abraham, Jeeva Susan Author Somasundaram, Sripoorna Author Toteja, Ravi Author Makhija, Seema Author El-Serehy, Hamed A. text Acta Protozoologica 2017 56 2 93 107 https://www.mendeley.com/catalogue/7cfda465-a022-3360-848e-ade0a01d493b/ journal article 10.4467/16890027AP.17.008.7483 1689-0027 12637854 Morphology of Aponotohymena isoaustralis n. sp. Live cell: Average body size in vivo 148 × 46 µm (n = 25), length: width ratio 4:1, elongated body; dorsoventrally flattened about 2:1, flexible, colourless cytoplasm with a greenish appearance at the margins when observed at low magnifications. Yellowish green cortical granules about 0.8 µm in diameter aligned along the margins and irregularly distributed throughout the cell; they may also be randomly concentrated as clusters along the left margin and posterior end of the cell. Single contractile vacuole about 15 µm in diameter located below the AZM near the left margin. Cell division eve- ry 11 h. Encystment generally takes place within 24 h of starvation; the average diameter of the resting cyst in life is 64.53 µm (n = 12) with smooth ectocyst covered with mucus layer and granulated cytoplasm ( Fig 1A, B, E–H, J, K ). Fig. 1. Photomicrographs of live (A, B, E, F, G, H, J, K), protargol impregnated (C, D, I, L, M) and Feulgen stained (N) cells of Aponotohymena isoaustralis n. sp. A, B – cells in ventral view; C – ventral view of a vegetative cell with 5 transverse cirri arranged in a pseudo row (arrow); D – dorsal view of a vegetative cell; E – ventral view to show the arrangement of cortical granules (arrowheads) and colou- ration; F, G and H – ventral view of different cells showing flexible body; I – anterior portion of the dorsal surface showing dorsal rows (arrowhead); J – anterior portion of the cell showing contractile vacuole (arrowhead); K – cyst; L – anterior hook (arrowhead) of paroral membrane; M – dorsal view showing caudal cirri (2 + 2 + 3) (arrowheads); N – two macronuclei. AZM – adoral zone of membranelles, LMC – left marginal cirri, RMC – right marginal cirri. Scale bars: 20 µm. Nuclear morphology: Two macronuclear nodules each about 20 × 14 µm in size (in protargol preparations), spherical to ellipsoidal, located along the cell mid line, one about 19 µm away from the anteriormost part and the other about 16 µm away from the posterior- most part of the cell; distance between the two macronuclei is about 22.2 µm; micronucleus absent ( Fig. 1N ). Infraciliature characteristics: Adoral zone of membranelles (AZM) occupies about 34% of the body length in protargol preparations and is composed of 32– 40 membranelles. Undulating membrane (UM) with a characteristic hook at the distal end ( Notohymena - pattern); 18 FVT cirri with 3 frontal cirri, 4 frontoventral cirri, 1 buccal cirrus, 3 postoral ventral cirri, 2 pretransverse ventral cirri and 5 transverse cirri; transverse cirri equidistant to each other and usually arranged in a pseudo row. IV/2 and V/4 are closely placed whereas V/3 is distantly placed (distance between IV/2 and V/4 is 3.10 µm and between V/4 and V/3 is 5.14 µm). Marginal rows are separated (nonconfluent) posteriorly with about 30–38 cirri in right and left marginal row ( Figs 1C, L , 2A ; Table 1 ). Table 1. Morphometric characterization of protargol impregnated cells of Aponotohymena isoaustralis n. sp.

Character*	Mean	Min	Max	Median	SD	SE	CV
Body, length	132.3	115.5	161.2	129.4	12	2.4	9
Body, width	34.8	26.7	52.8	33.60	6.0	1.2	17.3
Adoral zone of membranelles, length	44.6	33.8	52.3	44.2	4.1	0.8	9.1
Adoral membranelles, number	36.4	32	40	36	2.1	0.4	5.7
Frontal cirri, number	3	3	3	3	0	0	0
Frontoventral cirri, number	4	4	4	4	0	0	0
Buccal cirri, number	1	1	1	1	0	0	0
Postoral ventral cirri, number	3	3	3	3	0	0	0
Pretransverse ventral cirri, number	2	2	2	2	0	0	0
Transverse cirri, number	5	5	5	5	0	0	0
Caudal cirri, number	7	7	7	7	0	0	0
Left marginal cirri, number	34.4	30	38	35	1.9	0.4	5.6
Right marginal cirri, number	32.9	30	38	32	2.1	0.4	6.4
Dorsal kineties, number	6	6	6	6	0	0	0
DK1, dikinetids number	20.4	18	22	21	1.8	0.4	8.8
DK 2, dikinetids number	20.4	18	22	21	1.8	0.4	8.7
DK3, dikinetids number	16.9	16	18	17	0.9	0.2	5.5
DK 4, dikinetids number	8	8	8	8	0	0	0
DM1, dikinetids number	8	8	8	8	0	0	0
DM 2, dikinetids number	6	6	6	6	0	0	0
Macronuclei, number	2	2	2	2	0	0	0
Micronucleus, number	0	0	0	0	0	0	0
Anterior macronucleus, length	20.8	16.1	38.4	19.5	5.1	1.0	24.5
Anterior macronucleus, width	14.3	10.1	17.5	14.6	2.1	0.4	14.8
Posterior macronucleus, length	19.4	13.8	26.4	19.5	2.6	0.5	13.4
Posterior macronucleus, width	13.6	7.6	18	13.9	2.4	0.5	17.4
Distance between the two macronuclei	22.2	9.3	41.6	18.8	9.0	1.8	40.8
CC in kinety 1, number	2	2	2	2	0	0	0
CC in kinety 2, number	2	2	2	2	0	0	0
CC in kinety 4, number	3	3	3	3	0	0	0

*All measurements are in µm (n – sample size – 25). CC – caudal cirri; CV – coefficient of variation (%); DK – dorsal kineties; DM – dorsomarginal; Max – maximum; Min – minimum; SD – standard deviation; SE – standard error. The dorsal ciliature is of typical oxytrichid pattern with 4 dorsal kineties (DK 1–4) and 2 dorsomarginal rows (DM 1,2 ). Three dorsal kineties (DK 1–3 ) encompass the entire length of the cell whereas DK 4 commences near midline of the cell and extends to posterior end. DM 1 and DM 2 start at the anterior end of the cell and terminate at 1/3 rd of the cell length. Length of the dorsal bris- tles varies from 0.7 to 2.15 µm (average bristle length in DK 1 = 2.15 µm, DK 2 = 1.82 µm, DK 3 = 1.04 µm, DK 4 =1.65 µm, DM 1 = 1.74 µm and DM 2 = 0.7 µm; n = 10 cells). Seven caudal cirri (CC) are arranged in 2 + 2 + 3 pattern at the end of DK 1, 2 & 4 respectively; caudal cirri are about 6.25 µm long ( Figs 1D, I, M , 2B ; Table 1 ).