Raphidascaris acus (Bloch, 1779) Railliet & Henry, 1915

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 148-150

* Raphidascaris acus (Bloch, 1779) Railliet & Henry, 1915

Synonyms: Raphidascaris canadensis Smedley 1933 ; Raphidascaris laurentianus Richardson, 1937 ; Raphidascaris alius Lyster, 1940

Description (after J. D. Smith 1984b).

L 4 males: mean 2.777 (range 2.522–3.197) long; L 4 females: 2.961 (2.348–3.393) long. Three lips present, equal in length. Single interlabium between subventral lips, much reduced in adults. Lateral interlabia absent. Four double papillae, two on dorsal lip, one on each subventral lip. Lateral amphid and single papilla on each subventral lip. Cuticle with distinct striations. Lateral alae from base of lips to tail. Deirids small, at level of excretory pore. Tail long, conical, pointed ( Fig. 85 A). Phasmids in midregion of tail. Male gonad from slightly anterior of midpoint of larva to rectum. Testis thin-walled. Posterior portion of gonad with walls of low cuboidal cells. Spicule pouches extending dorsally and anteriorly from dorsal wall of rectum. Developing spicules narrow, not cuticularized ( Fig. 85 A). Female gonad 20–25% of length of larva. Vagina slightly anterior to midpoint of larva ( Fig. 85 B). Uterus dividing into two posteriorly directed branches, slightly posterior from vagina. Oviduct proximal to uterus, short. Ovaries straight, thin-walled, filled with large germinal cells.

L3: males 1.682 (1.444–2.056) long; females 1.925 (1.690–2.248) long. Anterior end with ventral boring tooth, four large papillae subdorsally and subventrally, pair of single papillae, and pair of amphids laterally. Lips absent. Lateral alae from anterior end to tail, widest in anterior third. Cuticle with fine transverse striations. Deirids small, at level of excretory pore. Tail conical, pointed. Phasmids in midregion of tail. Three rectal cells around anterior part of rectum. Sexes distinct. Vaginal primordium an ovoid mass of cuboidal cells, embedded in ventral body wall, near midpoint of larva. Two ovaries extending posteriorly from vagina. Gonad in male straight, elongate, ventral to intestine in posterior quarter of body.

L2: body 0.899 (0.787–1.009) long. Anterior end bluntly rounded with 4 large papillae subdorsally and subventrally. Mouth opening approximately triangular in outline. Conical boring tooth at ventral apex of mouth opening. Lips absent. Lateral alae narrow. Cuticular striations not seen. Deirids small, at level of excretory pore which is slightly posterior to nerve ring. Preventriculus claviform. Ventriculus about as long as wide, with posteriorly directed ventricular appendix . Genital primordium ovoid, comprising four to eight cells. Tail conical, pointed.

For detailed dimensions and disposition of the various organs in L4, L3 and L2 see J. D. Smith (1984b). Site: viscera

Hosts: Acipenser fulvescens (25); Ambloplites rupestris (10, 17); Catostomus commersonii (7, 16, 21, 23); Coregonus artedi (7, 21, 23, 29); Coregonus clupeaformis (1, 7, 13, 19, 29); Cottus bairdii (19); Cottus cognatus (1); Esox lucius (1, 15, 16, 29); Etheostoma caeruleum (11); Etheostoma exile (16); Etheostoma nigrum (11); Fundulus diaphanus (16); Hiodon alosoides (21, 23); Ictalurus punctatus (10); Lepomis gibbosus (20); Lota lota (29); Morone chrysops (18); Moxostoma anisurum (21); Myoxocephalus thompsonii (33); Notemigonus crysoleucas (16); Notropis hudsonius (21, 23); Perca flavescens (4, 5, 7, 8, 9, 11, 12, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33); Percina caprodes (21, 23); Percopsis omiscomaycus (21, 23); Pimephales notatus (16); Pimephales promelas (16); Ptychocheilus oregonensis (2, 6); Pungitius pungitius (3); Salvelinus namaycush (29); Sander canadensis (21, 23); Sander vitreus (7, 12, 14, 21, 23); Thymallus arcticus (1, 29); Tinca tinca (34); Umbra limi (16)

Distribution: Alberta, British Columbia, Labrador, Manitoba, Ontario, Quebec, Yukon Territory

Records: 1. Arthur et al. 1976 (YT); 2. Anon. 1978 (BC); 3. Leong & Holmes 1981 (AB); 4. J. D. Smith & Anderson 1981 (ON); 5. J. D. Smith & Anderson 1982 (ON); 6. Arai & Mudry 1983 (BC); 7. Poole 1983 (MB); 8 . Poole & Dick 1984 (MB); 9. Baker 1984b (ON); 10. J. D. Smith 1984a (ON); 11. J. D. Smith 1984b (ON); 12 . Poole & Dick 1986 (MB); 13. Samuel 1985 (AB); 14 . Poole & Dick 1985 (MB); 15. Shostak & Dick 1986 (MB); 16. J. D. Smith 1986 (ON); 17. Dechtiar & Lawrie 1988 (ON); 18. Dechtiar & Nepszy 1988 (ON); 19. Dechtiar et al. 1988 (ON); 20. Dechtiar et al. 1989 (ON); 21. Szalai 1989 (MB); 22. Szalai & Dick 1991 (MB); 23. Szalai et al. 1992a (MB); 24. Szalai et al. 1992b (MB); 25. Choudhury & Dick 1993 (MB); 26. Zelmer 1994 (AB); 27. Zelmer & Arai 1998 (AB): 28. Carney & Dick 2000 (MB); 29. Johnson & Dick 2001 (ON); 30. Baldwin & Goater 2003 (AB); 31. Zelmer & Arai 2004 (AB); 32. Marcogliese et al. 2005 (QC); 33. Carney et al. 2009 (ON); 34. Marcogliese et al. 2009 (QC)

Figures

FIGURE 85. * Raphidascaris acus (Bloch, 1779) Railliet & Henry, 1915. A. male L 4, posterior end showing developing spicules and vas deferens, lateral view; B. female L 4, vagina, lateral view. (Redrawn from J. D. Smith 1984 b)