Trichodina cf. heterodentata Dunkan, 1977

Yuryshynets, Volodymyr, Ondračková, Markéta, Kvach, Yuriy & Masson, Gérard, 2019, Trichodinid Ectoparasites (Ciliophora: Peritrichia) of Non-native Pumpkinseed (Lepomis gibbosus) in Europe, Acta Protozoologica 58 (2), pp. 69-79 : 71

Trichodina cf. heterodentata Dunkan, 1977

( Figs. 2 A, B )

Locality. D6 borrow pit, Danube river drainage, Czech Republic

Comparative description: Medium-sized trichodinid with saucer-shaped body, 53.9–56.3 (54.5, 3) in diameter. Adhesive disc concave, 43.2–47.2 (45.6, 3) in diameter; surrounded by finely striated border membrane 3.6–4.6 (4.2, 3) wide. Diameter of denticle ring 28.7– 29.9 (29.3, 3). Centre of adhesive disc with texture identical to rest of adhesive disc, diameter of central area 9.3–14.0 (11.6, 3). Number of denticles 23–25. Number of radial pins per denticle: (10–11, 2). Length of denticle 6.8–7.4 (7.1); span 12.1–15.4 (14.1); length of ray 6.3–8.0 (6.2); width of central part 1.9–3.0 (2.8); length of blade 5.0–5.2 (5.1). Individuals with visible adoral spiral were not observed. Blade is narrow and sickle-shaped, apex does not extend beyond the Y+1 axis. Apophysis of the blade is well-developed and prominent. Tangent point sharp, with distal margin at same level or slightly higher than tangent point. Posterior margin forming deep curve with deepest point in lower half of curve, slightly lower than blade apex. The central part is delicate, with no visible posterior projection, tapering to rounded point fitting tightly into pre- ceding denticle. Central part extends more than halfway to Y axis. Section above and below X axis similar in shape. Ray connection short and broad. Ray apophysis distinct.

Base of ray broad, tapering to sharp point. Ray mostly straight, parallel to Y-axis or slightly directed posteriorly or anteriorly. Section of denticle above X axis to section below, <1 (ratio 0.75 to 0.85).

Comments: The biometric data and denticle shape of Trichodina cf. heterodentata generally corresponds with T. heterodentata from other localities ( Van As and Basson 1989) and Trichodina pediculus Ehrenberg, 1838 , with a wide range of biometric variation described by some authors ( Bauer 1984). In accordance to Kazubski and Migala (1968), T. pediculus is characterised by large size (adhesive disc 48.8–59.4), numerous denticles (28–29) and long rays. Differences in blade shape (“broad” in most part of species descriptions) can be connected with relatively “younger” age of descripted not adult individuals. Among the trichodinids, T. heterodentata is a cosmopolitan species and more than 35 species of fishes in 14 families have now been recognised as hosts for this parasite ( Martins et al. 2010) since it was first described by Duncan (1977). It is believed that this species originated from the African continent and has been dispersed to other countries together with shipments of cichlids destined for aquaculture ( Van As and Basson 1989). Some congeneric species ( Trichodina paraheterodentata Tang et Zhao, 2013 and Trichodina pseudoheterodentata Tang et al., 2017 ) with similarities in denticle morphology have recently been described (Tang and Zhao 2013, Tang et al. 2017).

Figures

Fig. 2. Trichodina cf. heterodentata Dunkan, 1977. A – silver impregnated photomicrograph; B – dentical diagram. Scale: 20 μm.