Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274: 90

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Ascarophis   sp.

Sites: intestinal lumen, stomach

Hosts: Coregonus nasus   (8); Cottus aleuticus   (5); Gadus macrocephalus   (5); Gadus morhua   (9); Hexagrammos decagrammus   (1, 5); Mallotus villosus   (6); Nautichthys oculofasciatus   (5); Oncorhynchus gorbuscha   (2, 4); Reinhardtius hippoglossoides   (7)

Distribution: Atlantic, British Columbia, Newfoundland, Northwest Territories, Pacific

Records: 1. Margolis 1977 (PA); 2. Anon. 1981 (BC); 3. Sankurathri et al. 1983 (PA); 4. Anon. 1984 (BC); 5. Ko 1986 (BC, PA); 6. Arthur et al. 1995 (AT); 7. Boje et al. 1997 (AT); 8. Choudhury & Dick 1997 (NT): 9. Khan et al. 2011 (NF)

Comments: Five Ascarophis   species are known currently from Canadian fishes. Appy (1981) provided good

descriptions and illustrations for A. arctica   , A. extalicola   and A. filiformis   ; the original descriptions of A. morrhuae  

and A. sebastodis   are relatively poor. Taxonomic problems concern morphology of the head of both sexes, and the

tails of males. Regarding the head, the pseudolabia of A. extalicola   have a blunt knob rather than the prominent conical apex of A. arctica   and A. filiformis   , so Appy (op. cit.) and Ko (1986) suggested that A. extalicola   might be related to “ Cystidicoloides   ” [species of which have been transferred to Salmonema   ; see page 100]. Regarding male tails, an area rugosa, narrow caudal alae, six pairs of post-cloacal papillae, and paired phasmids behind the 6th pair of papillae appear to be diagnostic. Appy (op. cit.) pointed out that papillae of the 5th pair are relatively small and ventral to the 6th pair, so earlier workers might have overlooked them. Indeed, Figure 55 View FIGURE 55 B illustrates an A. morrhuae   male, redrawn from Berland (1961), apparently with only five pairs of post-cloacal papillae, and structures that are [sic] “possibly the phasmids”. The description of neither A. morrhuae   nor A. sebastodis   mentions an area rugosa; there is no reference to paired phasmids for A. sebastodis   ; and caudal alae are not mentioned in the descriptions for either species, although Figure 55 View FIGURE 55 B illustrates them for A. morrhuae   . Both A. morrhuae   and A. sebastodis   should be redescribed and illustrated with special attention to the morphology of heads and tails.