Tripartiella obtusa Ergens & Lom, 1970

Tang, Fahui, Zhao, Yuanjun & Liu, Chunning, 2013, First records of three Tripartiella species (Ciliophora, Oligohymenophora, Peritrichida) from freshwater fishes along Yangtze River in China, Zootaxa 3681 (2), pp. 169-174 : 170

Tripartiella obtusa Ergens & Lom, 1970

Host: Rhinogobio typus

Locality: Qu County, Sichuan

Site: Gills

Date of sampling: April, 2012

Description ( Figs. 1, 2 , 7 ). The following morphological description was based on 25 specimens measured (n = 25). Small to medium freshwate r Tripartiella with a compressed body, diameter 21.5–30.5 (25.6 ± 2.7); adhesive disc 17.0–23.5 (20.5 ± 1.9); width of border membrane 1.5–3.0 (2.1 ± 0.2); diameter of denticle ring 10.0–13.0 (11.5 ± 0.9); number of denticles 21–24; number of radial pins per denticle usually 4–5; span of denticle 5.5–8.0 (6.8 ± 0.7); length of denticle 2.5–4.0 (3.0 ± 0.2); blade length 2.5–4.0 (3.1 ± 0.4), generally elongated and slanted obliquely backwards; distal blade surface straight, in parallel to border membrane, and a little higher than the sharp tangent point; anterior and posterior surfaces straight, but not in parallel with each other with anterior surface blade apophysis present, prominent just touching the Y +1 axis; blade apophysis absent or invisible. Central part relatively developed with a sharp point fitting loosely into preceding denticle and far away from the Y-1 axis. Shapes of the central part above and below the X-axis not symmetrical and 1.2–2.2 (1.5 ± 0.2) in width. Ray connection inconspicuous and barely distinguishable from the ray. Ray relatively long when compared to other Tripartiella species, and tip of ray directed slightly forward; ray apophysis absent and length of ray was 1.5–2.5 (1.9 ± 0.3); ratio between denticle above and below X axis less than two. Macronucleus U-shaped, external diameter 16.5–24.0 (18.2 ± 1.2) and internal diameter 12.0–18.5 (14.8 ± 1.5). Micronucleus elliptical, 1.5–2.5 (2.0 ± 0.5) in length and 1.0–2.0 (1.6 ± 0.5) in width, situated in + Y position. Adoral ciliary spiral turns about 180° - 230° around peristomial disc.

Remarks. In 1970, Tripartiella obtusa was originally found from gills of Gobio gobio by Ergens & Lom, the Czechoslovakia scientists ( Ergens & Lom, 1970). Later, it was found regularly but exclusively on the gills of the same host from Czechoslovakia by Lom and Haldar (1977). In terms of body size, it is very close to Tripartiella copiosa Lom, 1959 , but these two species can be easily distinguished by the morphological features of the denticles, especially the shape of denticles ( Lom, 1959). The morphology and morphometric data of the present population from the gills of Rhinogobio typus are well within the range of the original description by Lom & Haldar (1977). This finding has established a new host record, Rhinogobio typus , for Tripartiella obtusa , and this is also the first report in Asia, which extends the known host and geographic range for Tripartiella obtusa .

Figures

FIGURES 1 – 6. Photomicrographs of silver impregnated adhesive disc of Tripartiella species. 1 - 2. Tripartiella obtusa Ergens & Lom, 1970; 3 - 4. Tripartiella orthodens Basson & Van As, 1987; 5 - 6. Tripartiella macrosoma Basson & Van As, 1987. (Scale bars = 20 µm).

FIGURES 7 – 9. Diagramatic drawings of the denticles of three Tripartiella species. 7. Tripartiella obtusa Ergens & Lom, 1970; 8. Tripartiella orthodens Basson & Van As, 1987; 9 Tripartiella macrosoma Basson & Van As, 1987.