Philometra rubra (Leidy, 1856)

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274: 49-50

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Philometra rubra (Leidy, 1856)


Philometra rubra (Leidy, 1856)  

Synonym: Filaria rubra Leidy, 1856   Description (after Moravec et al. 2009a, and Moravec et al. 2013). With characteristics of the genus.

Males unknown.

Females: two gravid worms (measurements of four subgravid worms in parentheses) (after Moravec et al. 2013): body 108–184 (100–148) long. Maximum width 0.64–0.79 (0.64–0.68). Head end round, mouth opening small, dorso-ventrally elongate, surrounded by 14 cephalic papillae arranged in two circles, with lateral amphids. Four dorso-lateral and ventro-lateral papillae of outer circle large, dome shaped; four dorso-dorsal and ventroventral external papillae small; internal circle comprises one pair of minute lateral papillae and two pairs of minute sub-median papillae ( Fig. 33 View FIGURE 33 A). Oesophagus 2.6–3.4 long (2.3–4.6). Well developed anterior muscular bulb, and oesophageal gland with large cell nucleus. Nerve ring 0.33–0.39 (0.27–0.53) from anterior end, small ventriculus, oesophagus opens into intestine through distinct valve ( Fig. 33 View FIGURE 33 B). Intestine brown, ends blindly, attached by ligament to body wall near tail end ( Fig. 33 View FIGURE 33 C). Vulva and anus absent. Ovaries long, narrow, amphidelphic, situated near anterior end ( Fig. 33 View FIGURE 33 A) and posterior end ( Fig. 33 View FIGURE 33 C). Uterus occupies most of body space, filled with 1st -stage larvae, 0.46–0.53 long ( Fig. 33 View FIGURE 33 B), and eggs ( Fig. 33 View FIGURE 33 C). Tail end of adults round in lateral view ( Fig. 33 View FIGURE 33 D) and rectangular in dorso-ventral view ( Fig. 33 View FIGURE 33 C), bearing two large papilla-like projections ( Fig 33 View FIGURE 33 C).

Two subgravid worms (after Moravec et al. 2009a): body filiform, 40 and 59 long. Maximum width 0.48 and 0.50. Arrangement of head papillae and alimentary tract anatomy similar to that of gravid worms. Ovaries narrow, long, amphidelphic. Uterus filled with clusters of small spherical eggs.

Comment: the species identified by Séguin et al. (2011) as Philometra   sp. from wild-hatched captive-raised Morone saxatilis   in Canada probably represents P. r u br a.

Sites: body cavity, mesenteries

Host: Morone saxatilis  

Distribution: New Brunswick, Quebec

Records: 1. Hogans 1984 (NB); 2. Moravec et al. 2013 (NB, QC)