Philometroides nodulosus (Thomas, 1929) Dailey, 1967

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 52-54

Philometroides nodulosus (Thomas, 1929) Dailey, 1967

Synonym: Philometra nodulosa Thomas, 1929

Description (after Dailey 1966). With characteristics of the genus.

Males (five studied): cuticle smooth, lacking bosses. Body uniform in width except for anterior tapering, 2.39– 2.68 long, and 0.031–0.048 wide. Mouth small with three unelevated lips; inner ring of four papillae and outer ring of four pairs of papillae, and pair of amphids ( Fig.35 A). Oesophagus 0.623–0.688 long. Oesophageal gland 0.414 long with large nucleus. Nerve ring just behind anterior oesophageal swelling. Posterior end truncated with two ventral and two dorsal rounded swellings. Anus median. Spicules subequal, left one 0.137–0.164 and right one 0.130–0.161 long. Gubernaculum 0.048–0.059 long with terminal barb ( Fig. 35 B). Seminal vesicle begins just behind oesophageal gland, extending posteriorly 1.46, and ending in slender vas deferens that leads to posterior end.

Females (five gravid and 20 subgravid worms studied): cuticle covered with numerous irregularly spaced, rounded bosses confined to the cortical layer. Body of uniform width except at anterior and posterior ends where it tapers slightly, 30.0–44.5 long and 0.370–0.602 wide. Mouth with three elevated fleshy lips, an inner ring of four and an outer ring of eight evenly spaced papillae, and a pair of amphids ( Fig. 35 C). Oesophagus 1.91–3.1 long. Small ventriculus with four appendices projecting into intestine. Oesophageal gland with large nucleus ( Fig. 35 D). Anus absent, intestine ending blindly near bluntly rounded posterior end. Anterior ovary loops over oesophagus and extends caudad; posterior ovary doubles back on itself to project anteriad ( Fig. 35 E). Ovaries lead into uterus ( Fig. 35 D,E). Uterus a single, blind tubule packed with ova containing developing 1st -stage larvae that occupy most of body-cavity.

Comments: Dailey (1966) is an unpublished PhD thesis in which it is claimed that males of Philometroides nodulosus were described for the first time. Dailey (1967) presumably refers to an abstract of that thesis in which the n. comb. was first widely publicised. Dailey (1967) has not been traced, and does not appear in the reference list of this part of the Guide therefore. Adding to the confusion, there appear to be discrepancies in the measurements provided in the foregoing description of P. nodulosus and the illustrations (see Figure 35 ). A redescription of P. nodulosus is justified.

Sites: cheek galleries, eye, gills, subcutaneous

Hosts: Carpiodes cyprinus (2, 6); Catostomus catostomus (7); Catostomus commersonii (1, 3, 4, 5, 6, 7, 8, 9, 10,

11)

Distribution: Manitoba, Ontario, Quebec

Records: 1. Fantham & Porter 1948 (QC); 2. Dechtiar 1972b (ON); 3. Chan 1980 (ON); 4. Molnar et al. 1982 (ON); 5. Dechtiar & Christie 1988 (ON); 6. Dechtiar & Nepszy 1988 (ON); 7. Dechtiar et al. 1988 (ON); 8. Dechtiar et al. 1989 (ON); 9. Szalai 1989 (MB); 10. Szalai et al. 1992 (MB); 11. Dubois et al. 1996 (QC)

Figures

FIGURE 35. Philometroides nodulosus (Thomas, 1929) Dailey, 1967. A. adult male, en face view; B. adult male, posterior end, lateral view; C. adult female, en face view; D. adult female, anterior end, lateral view; E. adult female, posterior end, lateral view. (Redrawn from Dailey 1966)