Synonym: Thynnascaris reliquens Norris & Overstreet, 1975
Description (after Deardorff & Overstreet 1981). With characteristics of the genus. Body reaching greatest width near midbody. Cuticle with inconspicuous annulations and minute lateral alae. Alae become more apparent at levels behind rectum. Lips approximately equal in size, all longer than wide; flanges constricted near middle of lip; pulp pedunculated. Interlabia with height equal to or slightly greater than width at base. Interlabial grooves absent (Fig. 83 A). Preventriculus 11–13% of body length. Ventriculus narrower than widest level of preventriculus. Usually longer than broad; ventricular appendix departing without angulation from posterior portion of ventriculus. Nerve ring located at anterior 16–28% of preventriculus. Excretory pore at or immediately posterior to level of nerve ring. Tail with spined conical mucron.
Males: body 25–40 long by 0.5–0.9 wide. Preventriculus 3.3–4.5, ventriculus 0.141–300, ventricular appendix 1.2–1.7, and intestinal caecum 0.315–598 long. Spicules 1.7–2.4 long, relative length varies: spicule ratio 1:0.6– 1.3. Caudal papillae 27 to 33 pairs: 23 to 29 pre–cloacal pairs, four to five post–cloacal pairs with 3rd pair from tail end doubled; para-anal papillae lacking. Distinct medio-ventral organ, papillated. Tail reflexed ventrad, 0.123– 0.185 long, including multispinous process (Fig. 83 B).
Females: body 21–44 long by 0.5–1.1 wide. Preventriculus 2.9–5.0, ventriculus 0.142–0.286, ventricular appendix 1.0–2.9, and intestinal caecum 0.394–0.788 long. Vulva without protruding lips, opens 6.5–17.0 from anterior end. Ovaries rarely extend beyond anterior level of vulva. Tail 0.370–0.574 long, including multispinous process (Fig. 83 C).
Site: stomach
Host: Xiphias gladius
Distribution: Atlantic
Record: Hogans et al. 1983