Truttaedacnitis sphaerocephala (Rudolphi, 1809) Petter, 1974

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 155

Truttaedacnitis sphaerocephala (Rudolphi, 1809) Petter, 1974

Synonym: Bulbodacnitis sphaerocephala (Rudolphi, 1809) Maggenti, 1971

Description (after Choudhury & Dick 1996b, and Moravec 2013). With characteristics of the genus. Moderately large worms with thick cuticle. Anterior end often dorsally flexed and mouth opening markedly oblique. Mouth opening bordered by cuticular collarette bearing weakly developed inconspicuous longitudinal riblike structures (“teeth”). Ventral cephalic ridge traverses ventral side at level of pseudobuccal capsule; excretory pore occurs between the two hemispheres of this ridge. Two very narrow alae extend along anterior part of body, starting below level of posterior end of pseudobuccal capsule. Two broad closely apposed cephalic plates are on either side of the mouth opening ( Fig. 86 B). The pseudobuccal capsule has a thickened cuticular lining surrounded by musculature that becomes progressively thinner posteriorly. Hemizonid and asymmetrical deirids behind nerve ring. Tail conical. [Measurements in square parentheses are taken from Moravec’s (2013) description of European material.]

Males: 11.9–16.2 long. [11.24–22.71 long; maximum width 0.31–0.48. Nerve ring 0.468–0.640 from anterior end. Oesophagus 1.64–2.12 long. Tail conical, 0.265–0.374 long, pointed tip.] Testis single. Posterior end of body bent ventrally, with well developed pre-cloacal sucker. Spicules equal, bent [0.270–0.440 long] ( Fig. 89 ). [Gubernaculum 0.075–0.096 long.] Arrangement of caudal papillae similar to that of T. clitellarius above ( Fig. 87 B).

Females: 15.9–18.8 long. [17.44–28.56 long; maximum width 0.30–0.48. Nerve ring 0.468–0.640 from anterior end. Oesophagus 1.89–2.28 long. Deirids asymmetrical, 0.075–0.160 from anterior end. Tail 0.374–0.562 long, conical, tip rounded with mucron.] Vulva in posterior half of body, anterior lip large, overlapping posterior lip. Eggs oval, thin-walled, [0.070–0.092 x 0.045–0.064].

Site: spiral valve

Host: Acipenser oxyrinchus

Distribution: Atlantic, New Brunswick

Records: Linkletter et al. 1977 (AT); Appy & Dadswell 1978 (NB)

Figures

FIGURE 86. Truttaedacnitis spp.: heads showing cephalic plates. A. T. truttae; B. T. sphaerocephala; C. T. clitellarius; D. T. pybusae. (A., B. and C. redrawn from Choudhury & Dick 1996 b; D. redrawn and rotated from Pybus et al. 1978 a)

FIGURE 87. Truttaedacnitis clitellarius (Ward & Magath, 1917) Petter, 1974. A. male, anterior end showing excretory pore and duct, lateral view; B. male, posterior region showing pre-cloacal sucker, spicules and papillae, lateral view; C. female, posterior end showing posterior coiled ovary, rectal glands, phasmid and mucron, lateral view. (Redrawn from Choudhury & Dick 1996 a)

FIGURE 89. Truttaedacnitis sphaerocephala (Rudolphi, 1809) Petter, 1974. Male, posterior end showing papillae and bent spicules, lateral view. Arrow indicates the 9 th papilla. (Redrawn from Choudhury & Dick 1996 b)