Rhabdochona cotti Gustafson, 1949

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 71-73

Rhabdochona cotti Gustafson, 1949

Description (after Gustafson 1949, and Moravec & Arai 1971). With characteristics of the genus. Slender worms, attenuated at both ends. Pseudolabia rudimentary. Prostom funnel-shaped, without basal teeth, with 14 teeth projecting anteriorly from longitudinal ridges. Oesophagus comparatively short, divided into anterior muscular and posterior glandular portions. Deirids small (“shape of deirids not determined”), lateral, opposite mid-portion of buccal cavity.

Males (measurements of paratypes according to Moravec & Arai (1971) in parentheses): 7.65–10.6 (12.76) long, 0.080–0.131 (0.154) maximum width. Prostom 0.017–0.020 (0.015), “total stoma” 0.082–0.122 (vestibule including prostom 0.093–0.096), muscular oesophagus 0.272–0.340 (0.252–0.285), and glandular oesophagus 0.80–1.28 (0.87–1.22) long. Nerve ring 0.17–0.22 (0.165–0.195) and excretory pore 0.22–0.32 (0.216) from anterior end. Left spicule 0.309–0.370 (0.354–0.357) long, of which 0.163–0.197 is the alate portion; according to Moravec & Arai (op. cit.) its distal tip appears “lanceolate and similar to that of R. canadensis ” (see above). Right spicule 0.085–0.120 (0.102–0.105) long, scoop-shaped, with rounded posterior end lacking distinct barb distally. Length ratio of right to left spicule 1:3.08 to 1:–3.64. About eight pairs of pre-cloacal papillae, all subventral except for the 3rd sublateral pair anterior to cloaca. Six pairs of post-cloacal papillae, of which the 2nd pair is is sublateral and the others subventral. Tail conical, 0.285–0.294 long, with distinctly rounded tip, without cuticular spike ( Fig. 45 A).

Females (measurements of paratypes according to Moravec & Arai (1971) in parentheses): 18.3–34.2 (19.20– 29.48) long, 0.19–0.31 (0.258–0.462) maximum width. Prostom 0.025–0.036 (0.024–0.027), “total stoma” 0.102– 0.143 (vestibule including prostom 0.099–0.111) [ Fig. 45 B], muscular oesophagus 0.374–0.626 (0.330), glandular oesophagus 1.46–1.92 (not determined) long. Nerve ring 0.21–0.43, excretory pore 0.305–0.580, and vulva 11.4– 20.9 from anterior end. Tail 0.204–0.350 (0.210–0.300) long, conical with distinct rounded tip, without cuticular spike ( Fig. 45 C). Eggs embryonated when laid, 0.032–0.033 x 0.018–0.020, with two long single (rarely double) filaments.

Site: intestine

Hosts: Cottus asper (1); Cottus bairdii (2, 6, 7); Cottus cognatus (1, 3, 4, 5, 8); Cottus caeruleomentum (9) Distribution: Alberta, British Columbia, Ontario

Records: 1. Bangham & Adams 1954 (BC); 2. Dechtiar 1972a (ON); 3. Mudry & Anderson 1977 (AB); 4. Anon.

1978 (BC); 5. Arai & Mudry 1983 (BC); 6. Dechtiar et al. 1988 (ON); 7. Dechtiar & Lawrie 1988 (ON); 8.

Dechtiar et al. 1989 (ON); 9. Moravec & Muzzall 2007 (BC)

Figures

FIGURE 45. Rhabdochona cotti Gustafson, 1949. A. male, posterior end, lateral view; B. female, anterior end, lateral view; C. female tail, lateral view. (Redrawn from Moravec & Arai 1971)