Haplonema hamulatum Moulton, 1932

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 171-173

Haplonema hamulatum Moulton, 1932

Description (after Arthur & Margolis 1975). With characteristics of the genus. [Two sets of measurement are given, the first for syntypes, the second in parentheses for material collected subsequently.]

Males: syntypes length not available (8.31–11.76); maximum width 0.20 (0.14–0.20). Cuticular striations very fine. Head with four submedian double papillae, two lateral amphids, and six radially arranged ridges, one extending from each of the papillae and amphids to rim of mouth. Lips and buccal capsule absent, mouth opening directly into oesophagus, 0.512 (0.595–0.890) long. Nerve ring 0.248 (0.312–0.383) from anterior end. Excretory pore slightly posterior to oesophago-intestinal junction, distance from anterior end not available for syntypes (0.717–1.036). Lateral alae extending 1.03 (0.828–1.840) posteriorly from anterior end. Digitate deirids anterior to oesophago-intestinal junction, 0.392 (0.450–0.754) from anterior end ( Fig. 99 A). Testis originating a little anterior to anus and extending anteriorly beyond mid-body before doubling back to proceed posteriorly and join seminal vesicle. Spicules short, about equal: left one 0.130–0.151 (0.118–0.157), right one 0.130–0.150 (0.104–0.156) long. Gubernaculum wedge-shaped, 0.036–0.041 (0.027–0.045) long. Eleven pairs caudal papillae and one unpaired median pre-cloacal papilla. Phasmids not observed. Caudal alae present, extending from tip of tail to slightly anterior to 1st pair caudal papillae. Tail attenuated, 0.214–0.229 (0.156–0.230) long ( Fig. 99 B).

Females: 9.50–9.91 (9.51–10.88) long; maximum width 0.22–0.28 (0.16–0.18). Head and oesophagus

structure and cuticular striations as in males. Oesophagus 0.602–0.615 (0.628–0.709) long. Nerve ring 0.325–0.461

(0.310–0.372) from anterior end. Lateral alae extending posteriorly 1.03–1.84 (1.43–1.69) from anterior end.

Deirids 0.511–0.523 (0.486–0.582) from anterior end. Excretory pore a little posterior to oesophago-intestinal

junction, 0.692–0.794 from anterior end. Vulva prominent, protruding beyond body wall and guarded by two

digitate lateral projections, 5.42–5.79 (5.97–6.67) from anterior end ( Fig. 99 C). Muscular vagina directed

anteriorly, 0.177–0.186 (0.195–0.266) long. Uteri amphidelphic. Eggs 0.065–0.077 x 0.043–0.051 (0.050–0.072 x

0.047–0.058). Tail 0.457–0.486 (0.0470–0.538) long. Phasmids not observed.

Site: intestinal lumen

Hosts: Lota lota (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14); Oncorhynchus mykiss (8, 11); Prosopium williamsoni (8, 11); Salvelinus malma (8, 11)

Distribution: Alberta, British Columbia, Ontario, Yukon Territory

Records: 1. Moulton 1932 (ON); 2. Bangham & Hunter 1939 (ON); 3. Bangham 1941 (ON); 4. Bangham & Venard 1946 (ON); 5. Bangham 1955 (ON); 6. Arthur & Margolis 1975 (YT); 7. Arthur et al. 1976 (YT); 8. Anon. 1978 (BC); 9. Anon. 1981 (BC); 10. Leong & Holmes 1981 (AB); 11. Arai & Mudry 1983 (BC); 12. Anon. 1984 (BC); 13. Dechtiar & Lawrie 1988 (ON); 14. Dechtiar et al. 1988 (ON)

Figures

FIGURE 99. Haplonema hamulatum Moulton, 1932. A. female, anterior end, ventral view; B. male, posterior end, ventral view; C. female, vulvar region, lateral view. (Redrawn from Arthur & Margolis 1975)