Trichodina jenynsii, S. MARCOTEGUI & Basson & R. MARTORELLI, 2016

S. MARCOTEGUI, Paula, Basson, Linda & R. MARTORELLI, Sergio, 2016, Trichodinids (Ciliophora) of Corydoras paleatus (Siluriformes) and Jenynsia multidentata (Cyprinodontiformes) from Argentina, with Description of Trichodina corydori n. sp. and Trichodina jenynsii n. sp., Acta Protozoologica 55 (4), pp. 249-257 : 253

Trichodina jenynsii n. sp. ( Figs 3A–D , 4C ; Table 1)

Description. Medium to large freshwater trichodinid: body diameter, 62.6–76.3 (65.5±4.5); adhesive disc diameter, 54.6–66.9 (57.8±3.9); denticulate ring diameter, 29.9–41.5 (34.3±3.6); width of border membrane, 2.8–6.7 (4.4±1.2); denticle number, 23–26 (25); number of radial pins per denticle, 14–16 (16); denticle span, 16.1–22.0 (19±2.0); denticle length, 6.2–8.4 (6.9±0.6); central zone of adhesive disc dark; blade length, 4.7– 7.7 (5.9±0.9). Blade large, filling large part of space between Y-axes. Distal blade margin almost parallel to border membrane, where-after it slants sharply towards apex. Tangent point narrow, almost on same level as distal margin. Apex of blade prominent, extending beyond Y-axes and clearly distinguishable from anterior blade margin. Anterior blade margin with a prominent apex that shows a clear notch proximal to apex in most denticles of some specimens. Notch present in all specimens, but not equally prominent in all. Blade apophysis present. Posterior blade margin deeply rounded, mostly L-shaped with deepest point lower or at same level as blade apex. Posterior projection well developed, present in majority of denticles. Section connecting blade and central part robust, indistinguishable from thinnest part of blade. Central part well developed, characteristically squat and short, with broadly rounded point that fits tightly into preceding denticle. Central part extends halfway to Y-1 axis. Shape of central part above and below X-axis not similar, upper part with indentation, slanting towards posterior projection, with lower portion more angular. Central part, 3.8–5.7 (4.3±0.6) wide. Section connecting central part and ray very robust. Ray apophysis present, but weakly developed. Ray base projecting from ray connection very robust. Ray tapers rapidly to a narrow, rounded point. Rays strongly developed and prominent, but show irregularities in shape and in smoothness along their length, as well as in amount of slanting. Some rays prominently slanted posteriorly, others slanted anteriorly, all crossing Y axes (either Y-1 or Y+1 respectively), while others are straight, either running along Y-axes or between them. No matter the angle of rays, all are straight, none showing a curved nature. Ray length, 6.8–11.5 (8.7±1.6). Ratio of denticle above to denticle below X axis less than 1 (0.66–0.69). Macronucleus horseshoe-shaped, external diameter 43.7–45.4 (44.5±0.9). Adoral ciliary spiral 380–410°.

Figures

Fig. 3. Photomicrographs of Trichodina jenynsii n. sp. from Jenynsia multidentata. A–C – Adhesive disc after dry silver impregnation. D – Macronucleus with methylene-blue staining. Scale bars: 10 μm.

Fig. 4. Diagrammatic drawings of denticles of trichodinids. A – Trichodina corydori n sp. from Corydoras paleatus. B – T. cribbi from Jenynsia multidentata. C – T jenynsii n sp. from J. multidentata. D – T. pediculus redrawn from Kazubski and Migala (1968). E – T. pediculus redrawn from Gaze and Wooten (1998). F – T. pediculus redrawn from Kazubski (1991c).